University of Ulsan Open Access Korea
Not a member yet
17799 research outputs found
Sort by
Predicting Recurrence after Sublobar Resection in Patients with Lung Adenocarcinoma Using Preoperative Chest CT Scans
No full textBackground Sublobar resection for lung cancer is usually guided by cutoff values for consolidation size (maximal diameter of the solid tumor component) and consolidation-to-tumor ratio (CTR). The effects of these factors as continuous variables and the reason for established cutoffs are, to the knowledge of the authors, unexplored. Purpose To quantitatively assess the predictive value of CTR and consolidation size for cancer recurrence risk after sublobar resection in clinical stage IA lung adenocarcinoma. Materials and Methods This retrospective study reviewed sublobar resection for clinical stage IA lung adenocarcinoma performed between January 2010 and December 2019. A restricted cubic spline function verified linearity by estimating recurrence probabilities using CTR and consolidation size obtained on preoperative CT scans. Statistical analyses included a Cox proportional hazards model to identify risk factors for cancer recurrence and the Cochran-Armitage trend test for the association between CTR and consolidation size. Results Of 1032 enrolled patients (age, 63.9 years ± 9.9 [SD]; 464 male patients), 523 (50.7%) and 509 (49.3%) underwent wedge resection and segmentectomy, respectively. Among patients with a CTR between 1% and 50% (n = 201), 187 (93.0%) had a consolidation size of less than or equal to 10 mm (P < .001). There was a positive association between the risk of recurrence with CTR and consolidation size (r2 = 0.727; P < .001). The recurrence rate showed the greatest increase when CTR was greater than 50% or consolidation size was greater than 10 mm. Specifically, the recurrence rate increased from 2.1% (three of 146) at 26%-50% CTR to 8.3% (nine of 108) at 51%-75% CTR, and from 4.4% (eight of 183) for 6-10-mm consolidation size to 11.9% (23 of 194) for 11-15-mm consolidation size. The probability of recurrence exhibited linearity and increased with CTR and consolidation size. Conclusion Cancer recurrence risk after sublobar resection for stage IA adenocarcinoma consistently rises with CTR and consolidation size. Current guideline cutoffs for sublobar resection remain clinically relevant given observed recurrence rates
The Effect of safety support from prime companies on safety behavior level of workers at partner workplaces - Focusing on the mediating effect of safety culture -
No full text고용노동부에 따르면 2017~2021년 산업재해로 인한 사망사고 중 40%가 협력사업장이며, 그 중 추락 · 끼임 · 부딪힘 등 기본 안전수칙 준수로 예방 가능한 사고가 전체의 62.6%(2021년 기준)이다. 따라서 협력사업장 근로자의 불안전한 행동을 제어할 수 있는 안전문화 정착이 시급하다. 따라서 본 연구는 협력사업장의 안전문화정착을 위한 방안으로, 원청의 안전지원이 협력사업장의 안전문화 조성과 소속 근로자의 안전행동에 미치는 영향을 조사하였다. 본 연구는 원청의 안전지원이 협력사업장 근로자의 안전행동 수준에 미치는 영향을 살펴보기 위한 단면조사 연구로서 2021년 한국산업안전보건공단에서 실시한 「2021년도 산업안전보건 실태조사」자료를 활용하였다. 연구를 위한 데이터는 건설 · 제조 · 서비스업 7,308개소 중 제조업 협력사업장 739개소를 선별하였으며, 선별된 자료는 SPSS 통계패키지(ver. 21)를 이용하여 기술통계와 위계적 회귀분석 등을 실시하였다. 조사결과, 협력사업장은 노동조합이 있는 경우가 91개소 12.3%였으며, 산업안전보건 전담부서를 갖추고 있는 경우가 94개소 13.9%로 대체로 산업안전보건체계 구축이 미흡한 것으로 조사되었다. 또한 원청의 안전지원이 협력사업장의 안전문화와 소속 근로자의 안전행동에 미치는 영향을 살펴본 결과, 원청의 안전지원은 협력 사업장의 안전문화에 정(+)의 영향을 미쳤으며 세부적으로는 원청의 안전지원이 협력사업장 근로자의 안전행동에 영향을 미치는 데 있어, 협력사업장 경영진의 리더십은 부분매개작용이 있으며, 안전소통과 교육 및 제도는 완전매개작용이 있는 것으로 조사되었다. 본 연구에 따르면 원청사업장의 적극적인 안전지원은 협력사업장의 안전문화를 활성화 시킬 수 있고, 이로 인하여 소속 근로자의 안전행동수준이 향상되어 재해를 예방할 수 있다. 협력사업장은 일반적으로 원청에 비해 안전능력이 부족하므로, 원청의 안전지원을 통해 협력사업장의 안전문화를 확산시킬 수 있고, 이로 인한 안전문화 정착으로 소속 근로자의 불안전한행동 제어를 통해 산업재해를 예방하는데 효과가 있을 것으로 기대할 수 있다.
According to the Ministry of Employment and Labor, 40% of fatal accidents due to industrial accidents between 2017 and 2021 were at partner workplaces, and 62.6% of all accidents (as of 2021) were preventable by following basic safety rules, such as falling, getting caught, or colliding. Therefore, this study investigated the effect of the prime companies’ safety support on the safety culture creation and safety behavior of workers in partner workplaces as a way to establish a safety culture in partner workplaces. This study was designed to examine the effect of safety support from prime companies on safety behavior level of workers at partner workplaces. It is a cross-sectional study using the Korea Occupational Safety and Health Agency’s 2021 Occupational Safety and Health data. The sample for the study is 739 manufacturing partner workplaces. Data were analyzed using descriptive statistics and hierarchical multiple regression analysis using SPSS (ver.21). According to this study, there were labor unions in 91 places and 13.9% in 94 places with departments dedicated to industrial safety and health, indicating that the establishment of an industrial safety and health system was generally insufficient. In addition, this study examined the effect of the prime companies' safety support on the safety culture of partner workplaces and the safety behavior of their workers. As a result of the hierarchical multiple regression analysis, safety support from prime companies had a positive (+) effect on safety culture at partner workplaces. Leadership of management appear to have a partial mediating effect on safety support from prime companies and safety behavior level at partner workplaces. Safety communication and education․systems appear to have a mediating effect on safety support from prime companies and safety behavior level at partner workplaces. According to this study, active safety support from the prime companies can revitalize the safety culture of the partner workplaces, thereby improving the level of safety behavior of workers to prevent accidents. Since partner workplaces generally lack safety capabilities compared to the prime companies, they can spread the safety culture of partner workplaces through safety support from the prime companies, and it can be expected to be effective in preventing industrial accidents by controlling the unsafe behavior of workers by establishing a safety culture
Evaluating the Performance of Cold-Formed Members under Central Axial Compression
No full text얇은 판을 가공하여 단면을 구성하는 냉간성형강 압축부재는 전체 좌굴과 함께 국부좌굴 또는 뒤틀림좌굴이 혼합되어 나타나므로 이에 대한 면밀한 안정성 검토가 요구된다. 이 논문에서는 최근 개정된 냉간성형강 설계기준에 대한 국내의 박 판 냉간성형강 소재의 적합여부와 압축재로서의 성능 만족여부를 확 인하고자 하였다. 공칭항복강도 275 MPa 급의 일반강재와 항복강도 420 MPa 급의 고강도강재를 선정하여 냉간단조성형으로 압축재를 제 작하고, 중심압축실험을 수행하여 기둥세장비와 단면형상에 따른 좌 굴거동을 확인하였다. 또한 실험 셋업에서 구현하지 못한 다양한 기 둥세장비에 따른 좌굴강도를 수치적으로 평가하기 위해 유한요소해석 모델을 구성하여 좌굴강도를 도출하였다. 또한 부재의 해석을 위해 해석 시간을 단축시킨 수정된 해석모델을 구성하고 앞선 해석 결과와 비교하여 적합성을 확인하였으며, 이를 통해 추가적인 유효좌굴길이 를 가지는 부재의 좌굴강도를 도출하였다. 실험결과 및 해석결과를 통해 냉간성형강 설계기준에서 제시하는 적용사항을 검토하였다. 유 효폭법과 직접강도법으로 산정한 강도는 중심압축실험강도보다 다소 보수적인 결과를 보였으나, 유한요소해석을 바탕으로 산정한 다양한 기둥세장비의 강도와 비교할 경우 비교적 잘 부합함을 나타내었다. 열간성형강에 대한 설계기준인 강구조 부재 설계기준(KDS 14 31 10) 으로 산정한 공칭압축강도는 중심압축실험결과 및 유한요소해석 결과 와 비교할 시 매우 큰 편차를 보였으며, 냉간성형강의 좌굴강도에 대 한 예측이 부정확함을 나타내었다. 실험적, 해석적 결과를 바탕으로 최근 개정된 냉간성형강 설계기준 의 압축재 조항 적용적합성을 확인하였고, 열간성형강 설계기준을 적 용하는 것이 부적절함을 입증하였다.|Since the cold forming steel compression member formed by processing a thin plate is mixed with local buckling or distortion buckling along with the entire buckling, a close stability review is required.
In this paper, we tried to confirm whether the domestic thin-plate cold-formed steel material is suitable for the recently revised cold-molded steel design standards and whether the performance is satisfied as a compression member. General steel with a nominal yield strength of 275 MPa and high-strength steel with a yield strength of 420 MPa were selected to produce compression materials through cold-forming, and a central compression test was performed to confirm buckling behavior according to column slenderness ratio and cross-sectional shape. In addition, in order to numerically evaluate the buckling strength according to various column detail equipment that was not implemented in the experimental setup, a finite element analysis model was constructed to derive the buckling strength. In addition, for the analysis of the members, a modified analysis model that shortened the analysis time was constructed and the suitability was confirmed by comparing it with the previous analysis results, and through this, the buckling strength of members with an additional effective buckling length was derived. Through the experimental and FEA results, the applications presented in the design criteria for KDS 41 30 30 were reviewed. The strength calculated by the effective width method(EWM) and the direct strength method(DSM) showed somewhat more conservative results than the central compression experimental strength, but it was found to be relatively well matched when compared with the strength of various column detail equipment calculated based on the FEA. The nominal compressive strength calculated by the steel structural design code(KDS 14 31 10), which is the design standard for hot-rolled steel, showed a very large deviation compared to the central compression test and FEA results, indicating that the prediction of the buckling strength of cold-formed steel was inaccurate.
Based on experimental and analytical results, the suitability of applying the compression material provisions of the recently revised design standards for cold-formed steel(KDS 41 30 30) was confirmed, and it was concluded that it was inappropriate to apply the design standards for hot forming steel.Maste
Erdafitinib in Asian patients with advanced solid tumors: an open-label, single-arm, phase IIa trial
No full textBackground: FGFR genomic aberrations occur in approximately 5-10% of human cancers. Erdafitinib has previously demonstrated efficacy and safety in FGFR-altered advanced solid tumors, such as gliomas, thoracic, gastrointestinal, gynecological, and other rare cancers. However, its efficacy and safety in Asian patients remain largely unknown. We conducted a multicenter, open-label, single-arm phase IIa study of erdafitinib to evaluate its efficacy in Asian patients with FGFR-altered advanced cholangiocarcinoma, non-small cell lung cancer (NSCLC), and esophageal cancer.
Methods: Patients with pathologically/cytologically confirmed, advanced, or refractory tumors who met molecular and study eligibility criteria received oral erdafitinib 8 mg once daily with an option for pharmacodynamically guided up-titration to 9 mg on a 28-day cycle, except for four NSCLC patients who received erdafitinib 10 mg (7 days on/7 days off) as they were recruited before the protocol amendment. The primary endpoint was investigator-assessed objective response rate per RECIST v1.1. Secondary endpoints included progression-free survival, duration of response, disease control rate, overall survival, safety, and pharmacokinetics.
Results: Thirty-five patients (cholangiocarcinoma: 22; NSCLC: 12; esophageal cancer: 1) were enrolled. At data cutoff (November 19, 2021), the objective response rate for patients with cholangiocarcinoma was 40.9% (95% CI, 20.7-63.6); the median progression-free survival was 5.6 months (95% CI, 3.6-12.7) and median overall survival was 40.2 months (95% CI, 12.4-not estimable). No patient with RET/FGFR-altered NSCLC achieved objective response and the disease control rate was 25.0% (95% CI, 5.5-57.2%), with three patients with stable disease. The single patient with esophageal cancer achieved partial response. All patients experienced treatment-emergent adverse events, and grade ≥ 3 treatment-emergent adverse events were reported in 22 (62.9%) patients. Hyperphosphatemia was the most frequently reported treatment-emergent adverse event (all-grade, 85.7%).
Conclusions: Erdafitinib demonstrated efficacy in a population of Asian patients in selected advanced solid tumors, particularly in those with advanced FGFR-altered cholangiocarcinoma. Treatment was tolerable with no new safety signals
Characterization of sacral chordoma and differential diagnosis from other sacral malignancy using [18F]FDG PET/CT
No full text2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET)/computed tomography (CT) is known to be a helpful imaging modality for sacral chordoma, but its detailed characteristics have not been fully described. The purpose of our study was to identify the [18F]FDG PET/CT imaging characteristics of sacral chordoma and compare them with other sacral malignancy. This retrospective study included patients who underwent [18F]FDG PET/CT because of a mass involving the sacrum. Investigated visual findings included visual score and distribution, and semiquantitative parameters measured included standardized uptake values (SUVmax, SUVpeak, SUVmean), tumor-to-liver ratio (TLR), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor size. Comparison studies and receiver operating characteristics (ROC) curve analysis were performed to differentiate between sacral chordoma and other sacral malignancy. Ten patients with sacral chordoma were finally included (M:F = 6:4, median age = 67 yr). On [18F]FDG PET/CT, sacral chordomas presented as a mass with minimal-moderate uptake with a usually heterogenous distribution. Compared with 12 patients with other sacral malignancies (M:F = 4:8, median age 42 yr), sacral chordoma showed a significantly lower TLR (median value 2.1 vs 6.3, P = .021). In ROC curve analysis, TLR showed the largest area under the curve (AUC) of 0.79 (cutoff ≤ 4.0; sensitivity 100.0%, specificity 58.3%; P = .004), and SUVmax showed the second largest AUC of 0.73 (cutoff ≤ 6.9; sensitivity 80.0%, specificity 66.7%; P = .034). [18F]FDG PET/CT of sacral chordoma showed minimal-moderate uptake. The TLR of [18F]FDG PET/CT was significantly lower than that of other sacral malignancy and was the most useful parameter for differentiating sacral chordoma, with the largest AUC. SUVmax could be another helpful semiquantitative parameter
A Study on the Improvement of Water Splitting Performance of Transition Metal-Based Electrocatalysts
No full textHydrogen energy is attracting attention not only due to its various applications but also because it is a green and sustainable energy source. Water splitting is an efficient method for producing hydrogen. Therefore, identifying suitable electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in the water splitting process is essential. Despite the effectiveness of noble metal-based electrocatalysts, their high cost and scarcity pose significant challenges. Hence, there is a critical need for active, stable, and cost-effective electrocatalysts for water splitting.
Driven by this challenge, this study focused on improving transition metal-based electrocatalysts for water splitting applications, with a particular emphasis on reducing costs and enhancing sustainability compared to noble metal-based electrocatalysts. Through various methodologies, including the optimization of activity and stability in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), significant progress was made.
We synthesized heterostructure catalysts, combining multiple components to leverage synergistic effects and overcome individual limitations. Furthermore, we explored depositing active component catalysts onto supported two-dimensional (2D) materials to enhance catalytic activity, stability, and mass transport properties. Additionally, modulation of electronic structures was investigated by introducing rare element-based materials as promoter components to enhance electrocatalyst activity and stability. Moreover, we investigated the benefits of atomic geometries of the compounds containing anion phosphate group and cation transition metals. The flexible coordination of this anion and the various oxidation states of transition metal can stabilize the intermediates in water splitting reactions, facilitating favorable adsorption and oxidation of water molecules.
These findings collectively demonstrate promising advancements in transition metal- based electrocatalysts for water splitting, highlighting their potential for widespread adoption in green hydrogen technologies. Through cost-effective and sustainable approaches, this research contributes to the advancement of efficient and scalable methods for hydrogen production.Docto
Personality traits and academic attitudes of medical students in the COVID-19 pandemic: a person-centered approach, empirical research, Korea
No full textPurpose: Since the coronavirus disease 2019 (COVID-19) pandemic, the educational environment has moved toward online-based education, which may significantly impact medical students' educational experiences. However, the same events may be understood differently by different individuals depending on their personalities. Therefore, the changing educational environment during the COVID-19 pandemic may not have been perceived equally by all students. This study aimed to investigate medical students' personality profiles and the difference between academic burnout and engagement according to their personality profiles.
Methods: During the 2021-2022 academic year, when online-based education was implemented due to the pandemic, a survey was conducted among medical students in Korea (N=325). First, we used latent profile analysis to identify the sub-types of the Big Five personalities. Second, we used analysis of variance and post hoc comparisons to study the difference between academic burnout and engagement among these sub-types.
Results: The Big Five personality traits of medical students in our sample were classified into three profiles. Profiles with relatively high neuroticism, while other personality traits were low, had both the highest academic burnout and academic engagement. Alternatively, the profiles showing relatively low neuroticism, while other personality traits were high, had the lowest academic burnout and the highest academic engagement.
Conclusion: Personality is a stable trait that affects an individual's behavior and response to the environment. Thus, individuals with specific personalities differ in their reactions to their environment. This may provide an advantage to some medical students' careers
Establishment of Preanalytical Quality Indicators and Current Status of Preanalytical Phase Laboratory Performance Monitoring in the Clinical Laboratories in Korea
No full textBackground: The preanalytical phase is more vulnerable to errors. Thisstudy aimed to establish preanalytical quality indicators (QIs) suitable for Korean clinical laboratories and investigate the current status of preanalytical phase performance monitoring in Korea using these QIs. Methods: We reviewed previous studies investigating preanalytical QIs including the International Federation of Clinical Chemistry (IFCC) model of QIs, to establish a set of QIs for Korean clinical laboratories. An e-mail survey consisting of this QI set was sent to 90 clinical laboratories. The collected data were analyzed, and performance measures were evaluated according to the quality specifications defined by the IFCC and the sigmascale method. Results: A model consisting of 23 preanalytical phase QIs was established. Approximately 47% (42/90) of clinical laboratories responded to the survey. The average result submission rate for each QI was 56% (standard deviation, 26%). The QIs with the highest and lowest result submission rates were “rejected samples due to hemolysis” (95%) and “recollected sample due to errors caused outside the laboratory” (17%). The QIs with the highest and lowest error rates were “hemolyzed sample detected by hemolytic index” (median, 0.546%; sigma performance level, “good”) and “samples not received” (median, 0.001%; sigma performance level, “very good”), respectively. Conclusions: This survey findings on preanalytical phase QIs could serve as a foundation for developing an external quality assessment program for clinical laboratories in Korea
The Effects of Creativity Activities Using Information Picture Books on Critical Thinking and Problem-Solving Ability of Young Children
No full text유아는 일상생활에서 여러 가지 문제에 부딪힌다. 이에 유아가 직면하는 문제를 다양한 방법으로 해결할 수 있는 비판적 사고와 문제해결력은 중요하다. 본 연구는 비판적 사고와 문제해결력 증진에 효과적인 정보 그림책의 필요성에 주목하여, 정보 그림책을 활용한 다양한 창의성 활동을 구성하여 비판적 사고와 문제해결력에 미치는효과를 알아보고자 하였다.이와 같은 목적에 따라 설정한 연구문제는 다음과 같다.연구 문제 1. 정보 그림책을 활용한 창의성 활동이 유아의 비판적 사고에 효과가있는가?연구 문제 2. 정보 그림책을 활용한 창의성 활동이 유아의 문제해결력에 효과가있는가?위와 같은 연구문제를 검증하기 위하여 U 광역시에 소재하는 Y 어린이집 6세 유아19명과 U 어린이집 6세 유아 18명으로 37명의 유아를 대상으로 하였다. 유아들은 실험집단 19명과 통제집단 18명으로 구성하고, 김현경(2002)이 설계, 제작한 비판적 사고와 안경숙(1992)이 작성한 문제해결력 검사 도구로 사전 검사하였다. 실험집단은 최미숙과 박지영(2010)이 분석한 정보 그림책 중 4권을 주 2회씩 총 16회로 8주간 창의성 활동을 하였고, 통제집단에는 아무런 처치를 하지 않았다. 본 활동이 끝난 후 실험집단과 통제집단에 비판적 사고와 문제해결력 검사 도구로 사후 검사를 하였다.본 연구에서 수집된 자료는 SPSS 27.0 통계프로그램을 사용하여 각 측정 도구의신뢰도를 알아보기 위해 Cronbach’s α를 산출하고, 실험집단과 통제집단의 동질성을확인하기 위해 독립표본 t-검증을 실행하였다. 정보 그림책을 활용한 창의성 활동 실시 후 정보 그림책을 활용한 창의성 활동이 유아가 지각하는 비판적 사고와 문제해결력에 미치는 효과를 알아보기 위하여 실험집단과 통제집단 간에 독립표본 t 검증을실행하였고, 집단 내 사전-사후 검사의 차이를 알아보기 위하여 대응표본 t 검증을 실행하였다.Maste
Optimal Design of an IPMSM for HEVs Using Circular Area Movement Optimization With the Pattern Search Method
No full textIn this paper, circular area movement optimization (CAMO), a novel global search algorithm, and its hybridization with the pattern search method (PSM) are proposed to solve the multimodal optimization problem. The CAMO is an optimization technique that creates a circular search area, moves the area, and searches the entire search area. Depending on the type of samples inside the area, two strategies are used to quickly and efficiently find the optimal point across the area. Also, the hybridization with the PSM supports fast convergence on adjacent optima from the points that are discovered in the global search using the CAMO. The effectiveness of the algorithm was verified by applying the CAMO to two test functions, and its superiority was confirmed through comparison with existing optimization algorithms. In addition, by applying the proposed algorithm to the optimal design of the cogging torque of an interior permanent magnet synchronous motor for a hybrid electric vehicle, a design that reduces the cogging torque by 95.65% was successfully derived. Lastly, stress analysis and demagnetization analysis were performed to examine the structural and thermal stability of the motor