ScienceWatch@KIOST
Not a member yet
29648 research outputs found
Sort by
Experimental Study on Flexural-Strengthening Limit of RC Slabs Flexurally Reinforced with Recycled-Waste Fishing-Net Panels
No full text본 연구는 재활용 폐어망 패널을 활용하여 휨 보강된 철근콘크리트(Reinforced Concrete, RC) 슬래브의 보강 한계를 규명하기 위해 수행되었다. 총 3기의 2경간 연속 RC 슬래브를 제작하여, 1기는 기준 슬래브로 사용하고 나머지 2기는 각각 정(+)모멘트 단면과 부(-)모멘트 단면에 재활용 폐어망 패널로 휨 보강하였다. 기준 슬래브와 보강 슬래브의 이론적 파괴 모드와 실험 결과를 비교·분석한 결과, 제안된 보강 한계의 실용성을 높이기 위해서는 보강 패널의 탈착 파괴 모드를 보강 한계 항목에 추가할 필요가 있음을 확인 하였다.
This study experimentally investigates the flexural-strengthening limit of reinforced concrete (RC) slabs using recycled-waste fishing-net panels. Three two-span continuous RC slabs were fabricated: one served as the reference specimen, and the other two were strengthened with recycled fishing-net panels in the positive (+) and negative (-) moment regions, separately. A comparison between the theoretical failure modes with the experimental results show that, to enhance the applicability of the proposed strengthening limit, one must consider the debonding failure mode of the strengthening panels.22Nkc
1H NMR and LC-MS guided isolation of secondary metabolites from the sponge Leucetta avocado
No full textThirteen biosynthetically related imidazole alkaloids (1–13), three bromopyrrole derivatives (14–16), and two non-ribosomal peptides (17–18), including three previously undescribed metabolites, were isolated from the sponge Leucetta avocado using a ^1H NMR-guided and GNPS molecular networking approach. Their structures were elucidated based on comprehensive NMR and HRESIMS analyses. Evaluation of the biological activities of these compounds is currently underway.2
Decomposition of respiratory and cardiac phase fluctuations using dual-band distributed CW radar
No full textRespiratory and cardiac rates can be estimated by analyzing a spectrum of linearly mixed phase fluctuations in a radar echo of an individual. However, there are high-order harmonics caused by time-varying respiratory rate, and the interference effect of the respiratory rate and its harmonics makes it difficult to estimate the cardiac rate with relatively low energy in a spectrum. To solve this problem, we exploit the independent component analysis method with dual-band distributed continuous wave radar for effective decomposition of phase fluctuations corresponding to respiratory and cardiac rates. In simulations and experiments, the respiratory and cardiac rates were successfully estimated by the proposed decomposition method, compared with conventional methods.11Nsciescopu
Eddy kinetic energy variability of the Kuroshio Extension and its upstream-downstream connectivity
No full textThe Kuroshio Extension (KE) system in the western North Pacific includes energetic meanders of the Kuroshio jet that are full of mesoscale eddies. This study analyzed the variability of eddy kinetic energy (EKE) in the KE region, focusing on its connectivity between the upstream and downstream regions. Three dominant modes of the EKE variability were identified through the empirical orthogonal function (EOF) analysis during 1993-2014, using a high-resolution reanalysis product. The spatial patterns of both the first and third modes present an overall out-of-phase relationship between the upstream and downstream regions. The principal component (PC) time series of the first EOF mode exhibits interannual to decadal variability and is correlated to the North Pacific Gyre Oscillations index with a time lag of about three years. It is also correlated with the PC time series of the third mode with a two-year time lag, suggesting that the third mode precedes the first mode associated with the westward propagation of baroclinic Rossby waves. The second mode, however, shows an in-phase spatial pattern between the upstream and downstream, and its PC time series exhibits strong seasonal variability with an interannual modulation. It is concluded that the upstream-downstream connectivity of the EKE in the KE region is explained by a combination of the out-of-phase variability on interannual to decadal timescales and the in-phase variability on seasonal to interannual timescales.11Ysciescopu
Potential habitat distribution of yellow croaker (Larimichthys polyactis) in Korean waters: Past and future
No full textYellow croaker (Larimichthys polyactis), commercially important in Korea and China, is a demersal species found mainly in the shallow Yellow and East China Seas. Given its demersal nature and its habitat in semi-enclosed seas, the species is vulnerable to climate change due to limited access to climate refugia. However, most habitat studies have focused on specific seasons or Chinese waters, with limited consideration of Korean waters and seasonal variation. Here, we projected seasonal habitat changes of yellow croaker in the 2050s under two climate scenarios (SSP1-2.6 and SSP5-8.5). In particular, a regional ocean climate model, which better captures local dynamics in narrow shelf regions like the Yellow and East China Seas, was used with four species distribution models driven by three environmental variables: bottom temperature, salinity, and depth. Results indicate that yellow croaker habitat was projected to contract year- round along the Korean coast in the Yellow and East China Seas, while expanding in the central Yellow Sea and across the East China Sea during summer and fall. These changes were driven by contrasting effects of bottom temperature and salinity: increasing temperatures raised the presence probability in the Yellow Sea but reduced it in the East China Sea, whereas decreasing salinity showed the spatially opposite pattern. Our findings suggest that the future habitat of yellow croaker may shift offshore, reducing availability along the Korean coast. These spatial shifts may adversely affect Korean yellow croaker fisheries by increasing operational costs due to longer travel distances to fishing grounds.1
Mineral Balance Index (Ca+K+Mg)/Na of Domestic Solar Sea Salt and a Proposal for Management Criteria
No full text본 연구는 국내 천일염의 무기질 조성을 정량하고, 국내·외 시료 비교를 통해 해양치유자원 관리에 활용 가능한 무기질균형지표((Ca+K+Mg)/Na)를 제안하였다. 국내 시료는 충남 태안, 전남 신안, 해남, 경기 안산 등에서 확보하였고, 일반성분(NaCl, 수분), 무기질(Na, K, Mg, Ca, Fe, Mn), 입도·표면구조를 분석하였다. 국내 천일염의 NaCl과 수분은 각각평균 85.7%와 6.0%로 국내 품질기준을 충족하였다. 무기질 평균치는 Na(214,208 mg/kg)>Mg(7,010 mg/kg)>K(5,902 mg/kg)>Ca(1,283 mg/kg)>Fe(5.3 mg/kg)>Mn(1.8 mg/kg) 순이었고, Mg와 K는 국외 대비 각각 약 2.3배와 5.6배 높았다. 제안 지표인 (Ca+K+Mg)/Na는 국내에서 평균 4.6%로, 국외(평균 1.6%) 대비 유의하게 높았다. ROC 분석에서AUC=0.94, Youden 임계값 2.53%가 도출되었으며, 2.5%로 보수 조정해도 판별 성능이 유지되었다. Clopper–Pearson 단측 95% 하한은 74%로, 기준의 보수적 신뢰성을 지지한다. 이에 (Ca+K+Mg)/Na 비율 2.5% 이상을 국내 천일염의관리 기준(제안)으로 제시하며, 본 결과는 국내 천일염의 무기질 균형 우수성과 해양치유자원의 가능성을 뒷받침한다.
This study quantifies the mineral composition of Korean solar sea salt and, through comparison with overseas products, proposes a mineral balance index ((Ca+K+Mg)/Na) for use in managing marine therapeutic resources.
Domestic samples were collected from multiple production areas (Taean, Shinan, Haenam, and Ansan), and analyzed for principal constituents (NaCl, Water content), minerals (Na, K, Mg, Ca, Fe, Mn), and grain-size/surface morphology.
Mean NaCl and moisture contents of Korean sea salt were 85.7% and 6.0%, respectively, satisfying domestic quality standards. Average mineral contents followed the order Na (214,208 mg/kg) > Mg (7,010 mg/kg) > K (5,902 mg/kg) > Ca (1,283 mg/kg) > Fe (5.3 mg/kg) > Mn (1.8 mg/kg); notably, Mg and K were approximately 2.3-fold and 5.6-fold higher than those of overseas sea salts, indicating greater mineral richness in the Korean products.
The proposed index, (Ca+K+Mg)/Na, averaged 4.6% in domestic samples and was significantly higher than that of overseas salts (1.6%). Receiver operating characteristic (ROC) analysis yielded an AUC of 0.94 with a Youden-optimal threshold of 2.53%; adjusting this cut-off to 2.5% preserved equivalent discrimination. A one-sided 95% lower confidence bound by the Clopper–Pearson method was 74%, supporting the conservativeness of the threshold.
Accordingly, we propose (Ca+K+Mg)/Na ≥ 2.5% as a management criterion for Korean solar sea salt, substantiating its favorable mineral balance and potential for resource utilization in marine healing applications.22Nkc
