ScienceWatch@KIOST
Not a member yet
29648 research outputs found
Sort by
Acoustic backscattering strength from sea ice in the summer measured in the Arctic Ocean during KAMAS-24
No full textKorea Acoustic Measurement in the Arctic Sea in 2024(KAMAS-24)는 2024년 8월에 북극해의 축치해와동시베리아해 해역에서 수행되었고, 이 실험에서 해빙에 의한 음파의 후방산란강도 를 측정하였다. 중주파수 음원과수직선배열센서를 이용하여 측정한 빔출력으로부터 산란각별 후방산란 강도를 추정하고 기존의 알려진 관측과 비교하였다.
KAMAS-24의 후방산란강도는 60 deg 이하에서는 산란각에 따른 변화 경향이 해빙이 없는 해수면의 경우와 유사하였다. 또한 저각에서 15 dB 이상의 변동이 나타났으며 해빙의 하부에 존재할 수 있는 용골에 의한 영향으로 생각된다. 음파가 해빙을 투과하여 추가 손실과 상쇄 간섭이 발생할 가능성이 있는 고각인 90 deg에서는 후방산란강도가 낮아지는 현상도 나타났다. 공개된 기존의 관측과 비교한 결과 KAMAS-24의 후방산란강도가 기존의 관측보다 낮았으며, 기후변화가 진행되며 여름철에 기온이 상승하여 해빙이 무르고 녹는 속도와 양이 증가하는 시기에 측정되었기 때문으로 생각된다.33Nscopuskc
Mesocosm-based Assessment of Concentration-dependent Ecotoxicological Effects of Hull Cleaning Wastewater on Coastal Plankton Communities
No full textIn-water hull cleaning, a widely used method to manage biofouling on ship hulls, inadvertently releases wastewater (HCW) containing heavy metals and particulates that may pose ecological risks. Despite its widespread release, the ecological risks of HCW remain poorly understood. In this study, a mesocosm experiment was conducted to evaluate the effects of increasing HCW concentrations (1%, 5%, and 10%) on coastal marine planktonic ecosystems, including phytoplankton, zooplankton, and periphyton. Exposure to ≥ 5% HCW resulted in sharp declines in phytoplankton abundance, coinciding with elevated dissolved copper (Cu) and zinc (Zn) levels, while zooplankton abundance declined rapidly
even at 1% exposure. In contrast, periphytic diatoms such asCylindrotheca closterium and Navicula spp. exhibited relative resilience, with abundances increasing up to 101 × 103 cells cm−2 during the later stages, particularly under nutrient-enriched conditions. Community composition analyses revealed a shift toward metal-tolerant, attached microalgal taxa at higher HCW concentrations. The results highlight
HCW as a multifaceted stressor capable of altering trophic structure and emphasize the importance of integrating ecological response indicators into future management strategies for robotic hull cleaning discharges.2
Small Fishing Vessel Detection Using Polarimetric Observables Fusion with Dual-Polarization Sentinel-1 SAR Data
No full textSynthetic Aperture Radar (SAR) is an efficient tool for monitoring ships. However, the detection accuracy of small fishing vessels is insufficient due to radar characteristics and image quality. Therefore, this study proposes a polarimetric fusion method focused on enhancing the detection performance of small fishing vessels using Sentinel-1 Single Look Complex (SLC) images. A combination of VH and VV polarization channels (fusVH) was applied to minimize radio frequency interference and azimuth smearing in SAR for detecting merchant ships, and the reflection symmetry (sym) was generated exploiting the fusVH image. Afterward, when the difference between sym and fusVH was less than 7.2 (dB) and sym was greater than -18.03 (dB), the maximum values of sym and fusVH were used to enhance the pixels of potential small ships. Using both sym and fusVH, small fishing vessels can be separated from merchant ships, which can be easily detected using fusVH images. The results were validated using 14 scenes from 2021 to 2023, and the average matching results were calculated to be 0.84 for the probability of detection rate and 0.29 for the false alarm rate.11Ysciescopu
남해동부해역에서 낙동강 담수와 대마난류 확장에 따른 성층 형성과 식물플랑크톤 군집의 월별 변동 특성
No full text연안역의 식물플랑크톤 군집은 계절에 따른 담수 유입, 해양 전선대 형성, 수온·염분 변화에 따른 성층 발달(Δρ)과 수직 안정도(N²)의 변동, 영양염 공급 등 다양한 요인에 의해 시·공간적으로 빠르게 변화한다. 본 연구에서는 남해 동부 해역, 즉 낙동강 하구에서 외해 및 거제 연안까지 아우르는 9개 정점을 세 구역(Zone I: 거제 연안, Zone II: 대마난류 영향역, Zone III: 낙동강 하구역)으로 구분하고, 2016년 6월부터 2017년 5월까지 해양 환경 특성과 식물플랑크톤 군집의 계절적 변화를 조사하였다.
하계 식물플랑크톤 군집 구조는 담수 유입과 대마난류의 영향으로 Δρ와 N²가 급변하며 형성된 성층 강도와 영양염 변동에 크게 좌우되었다. 6월에는 Zone II·III에서 Δρ 약 1–2 kg m⁻³, N² 5–10 s⁻² 수준의 약한 성층 발달과 함께 운동성이 유리한 와편모조류가 80%를 차지하였다. 7월 장마로 낙동강 담수가 유입되면서 Zone III의 염분은 9.7까지 낮아지고 질산염(68.4 μM)과 규산염(63.2 μM)이 증가하였으며, Δρ는 5.8 kg m⁻³, N²는 83.9 s⁻²로 조사 기간 중 가장 높게 관측되어 담수 기원의 규조류 Aulacoseira granulata가 우점하였다. 8월에는 성층 강화로 Δρ 6 kg m⁻³ 이상, N² 11 s⁻² 이상의 안정한 수층이 형성되며 와편모조류가 재출현했으나, Zone III에서는 여전히 고영양 환경을 선호하는 규조류가 90% 이상을 차지하였다. 한편, 수온 25 ℃ 전후에서 성장이 유리한 Alexandrium affine과 Margalefidinium polykrikoides는 6–7월에 발생하였으나, 8월 장강 희석수의 유입으로 수온 30 ℃ 전후, 저염분 (28–30 PSU) 환경이 형성되면서 급격히 소멸하였다. 가을(9–10월)에는 Δρ와 N²가 각각 1 kg m⁻³ 이하, 1.5 s⁻² 이하로 낮아지며 성층이 붕괴되고 저층 영양염이 유광층으로 공급되어 규조류 Pseudo-nitzschia delicatissima가 60–80%까지 증가하였다. 겨울철에는 Δρ≈0, N² < 2 s⁻² 의 완전 혼합 상태가 지속되며 수온과 광 부족으로 총 생물현존량이 낮게 유지되었고, 군집은 주로 규조류로 구성되었다. 봄(3–5월)에는 Δρ 1–2 kg m⁻³, N² 0.3–9.7 s⁻²로 점차 성층이 재형성되며, 동계 혼합으로 공급된 영양염과 수온·광 증가가 더해져 규조류 춘계 대발생이 나타났고, 동시에 독소 생산종 Alexandrium catenella가 상대적으로 높은 밀도로 출현하였다. 특히 A. catenella는 2–3월에 낮은 밀도로 관찰되다가 4월 Zone II에서 최대 1.3 × 10⁴ cells L⁻¹까지 증가하였으며 5월에 소멸하였다. 결과적으로, 낙동강 담수와 대마난류 확장은 Δρ 및 N²로 표현되는 계절별 수괴 구조를 변화시켜 우점종 교체와 유해 미세조류의 발생·소멸에 직접적인 영향을 미쳤다. 특히 식물플랑크톤 군집의 천이는 월별 환경 요인(Δρ, N², 영양염) 변화에 따라 뚜렷하게 나타났으며, 구역별로 상이한 양상을 보였다.2
Source-to-Sink of the Korean Shelf Mud Deposits since the Mid-Holocene
No full textBased on high-resolution seismic profiles and sediment data, the upper parts of the southeastern Yellow Sea Mud (SEYSM), Central South Sea Mud (CSSM), and Korea Strait Shelf Mud (KSSM) have been located along the Korean Peninsula since approximately 6 ka. Although shelf mud deposits have been studied extensively, the sediment budget of each shelf mud deposit requires further investigation. We intend to clarify the relationship between the three Holocene Korean shelf mud deposits, efficiency of estuary filtration, and oceanic dynamics along the coast of the Korean Peninsula. Approximately 32.5 to 43.8 × 106 tons of suspended sediments are supplied to the study area annually from multiple sources. These sediments are controlled by seasonal fluctuations in front and longshore currents that move along the coast of the Korean Peninsula. As a result, estimated annual accumulation rates in the SEYSM are 9.0–13.2 × 10 6 ton/year in the upper part of the SEYSM, and 5.3–8.1 × 10 6 ton/year in the CSSM. The KSSM has an annual accumulation rate of 4.6–6.4 × 10 6 ton/year. The upper part of the SEYSM accounts for 28–30% of the total sediment supply, the CSSM accounts for 17–18%, and the KSSM accounts for 14–15%. Finally, it was estimated that approximately 17–25% of the fine-grained sediments were supplied to the Ulleung Basin. The results of the sediment budget estimation provide crucial insights into sediment transport pathways, source-to- sink fluxes, and sediment sources in Korean shelf deposits, which have been debated until recently.11Nsciescopuskc
Magnetic Data Correction for Fluxgate Magnetometers on a Paramagnetic Unmanned Surface Vehicle: A Comparative Analysis in Marine Surveys
No full textUnmanned Surface Vehicle (USV) offers a cost-effective platform for high-resolution marine magnetic surveys using shipborne fluxgate magnetometers. However, platform-induced magnetic interference and electromagnetic interference (EMI) can degrade data quality, even with paramagnetic hulls. This study evaluates fluxgate magnetometer data acquired from a paramagnetic-hulled USV. Noise characterization identified EMI and maneuver-induced high-frequency noise, the latter of which was effectively reduced through low-pass filtering. We compared four different correction approaches addressing both vessel attitude and magnetization. The results demonstrate that the paramagnetic hull significantly reduces magnetic interference and shortens the duration of viscous magnetization (VM) effects caused by eddy currents in the platform, compared to conventional ferromagnetic vessels. Nonetheless, residual magnetization from onboard ferromagnetic components still requires correction. A method utilizing all nine components of the susceptibility tensor demonstrated improved accuracy and stability. Despite corrections, low-frequency VMrelated noise during azimuth changes and a consistent absolute offset (-200 nT) remain when compared to towed scalar magnetometer data. These findings validate the use of paramagnetic USV for vector magnetic surveys, highlighting their benefit in VM mitigation while emphasizing the need for further development in VM correction and offset correction to achieve high-precision measurements.11Ysciescopu
Thermodynamic evaluation of lithium recovery and freshwater production by sustainable hydrate-based desalination from brine solutions
No full textThe increasing global demand for lithium, a critical component in energy storage technologies, necessitates the development of sustainable recovery methods from diverse aqueous resources. In this study, we investigate a hydrate-based desalination (HBD) process utilizing chlorodifluoromethane (R22) gas as a hydrate former to simultaneously achieve lithium recovery and freshwater production from lithium-containing brines. Thermodynamic phase equilibrium experiments, synchrotron X-ray diffraction, Raman spectroscopy, and solid-state nuclear magnetic resonance confirm that lithium ions are excluded from the hydrate cages, whereas R22 molecules occupy the large cages of structure I hydrates. The effect of LiCl and Li2SO4 concentrations on hydrate formation kinetics was examined, revealing a significant dependence on subcooling temperature and salt concentrations. Furthermore, the thermodynamic correlation functions accurately predict the hydrate equilibrium shifts by lithium salts and the ideal maximum freshwater production ratio, highlighting its potential use for HBD process optimization. These findings demonstrate the feasibility of R22 HBD as a scalable strategy for sustainable lithium recovery and freshwater production from lithium-containing brines.11Nsciescopu
Development and validation of an HPLC-PDA method for the analysis of phycocyanobilin in Arthrospira maxima
No full textAn high-performance liquid chromatography (HPLC)-photodiode array (PDA) method was developed and validated for quantifying phycocyanobilin (PCB) in Arthrospira maxima extracts. While previous methods for PCB analysis lacked comprehensive validation and struggled with coelution issues, this approach demonstrated high specificity, accuracy, sensitivity, and reproducibility. Effective separation was achieved, with a retention time of 18.7 min. The calibration curve exhibited excellent linearity (r2 = 1.0000) across a concentration range of 3.125-50 µg/mL, with a limit of detection and limit of quantification of 0.22 and 0.67 µg/ mL, respectively. Recovery rates ranged from 97.75 to 103.36%, with relative standard deviations (RSD) between 0.50 and 2.14%, confirming the accuracy and reliability of the method. The intra-and inter-day precisions yielded mean contents of 0.122 (RSD: 1.61%) and 0.128 mg/g (RSD: 0.71%), respectively. Notably, this study is the first to validate an HPLC-PDA method for direct quantification of PCB in A. maxima with full validation parameters. By offering a standard for PCB analysis, this study contributes to quality control in research and industrial processes, paving the way for advancements in pharmacology and biotechnology. © 2025 Elsevier B.V., All rights reserved.33Nscopuskc
The Concept of Abuse of Process and its Applicability to International Court of Justice Advisory Proceedings
No full textIn the judicial proceedings, including the advisory opinion process, we may frequently face criticism and concerns about the “abuse of process” raised in certain cases. The past and pending advisory opinion proceedings before the International Court of Justice (‘ICJ’) have not been free from these concerns. Such concerns could be observed, especially when certain politically sensitive issues have been highlighted in the proceedings. However, while the relevant claims are quite commonly made, the concept of abuse of process itself has rarely been scrutinised in detail. Thus, this article aims to explore the concept of the abuse of process both theoretically and practically, not to regard it as a mere rhetorical expression. The necessity of conducting this research is suggested based on the following three grounds. First, regardless of the forum, concerns and criticisms about the abuse of process in judicial proceedings have been frequently raised. Recently raised criticisms regarding the general advisory jurisdiction of the International Tribunal for the Law of the Sea (‘ITLOS’) as a full Tribunal can be one such example. However, the concept of abuse of process has been rarely examined until now. This shows that now is an opportune time to conduct a theoretical study on the concept of abuse of process. Second, accusing and framing a particular case as an example of abuse of process should be done with caution, avoiding any discretionary use of this concept. Characterising a case as an abuse of process is seriously provocative and aggressive because it entails a risk of creating prejudice against the case at issue. In other words, an “abuse” of such a framing may also overshadow other legal issues which deserve attention. Hence, examining this concept conceptually may contribute to highlighting the perception that this can be recognised only in exceptional circumstances. Finally, the requirements and criteria to determine the abuse of process that this research will present may provide a complementary perspective for assessing the allegation of abuse of process over future advisory opinion cases before the ICJ. Hence, this article will first explore how to understand this concept by suggesting essential constituents. These are: (1) whether a right to initiate a certain judicial proceeding is invoked while not being compatible with the purpose and objective of constitutive instruments regulating such a procedure; (2) whether the invocation of that procedure is made with malicious or unjust intent; and (3) whether the institution of the judicial proceeding is to harm other parties or to achieve an undue advantage. Based on an understanding of these requisites, the article will examine the applicability of this concept to the ICJ’s advisory opinion cases and analyse some practical difficulties. This will show us some hints that higher thresholds will be taken by the ICJ in acknowledging the abuse of the advisory procedure in the future.1
GPS Surface Drifter System for Scale-Dependent Horizontal Diffusivity Estimation in the Northwestern Pacific
No full textScale-dependent horizontal diffusivity at the ocean surface is critical for modeling the dispersion of marine pollutants such as radionuclides and plastics. We developed a low-cost GPS surface drifter system (30 cm × 11 cm, ≈ 500 g) that transmits positions every five minutes via the Globalstar network for up to two months. In August 2024, twenty units were deployed from R/V Isabu, ten in the western Pacific (131.5°E, 19.5°N) and ten south of Japan (134.9°E, 28.1°N). A pair and triplet based deployment design enabled scale-specific analysis of surface dispersion. Relative dispersion statistics yielded diffusivities of 1.0 × 10² m² s⁻¹ at 10 km and 1.7 × 10⁴ m² s⁻¹ at 100 km in the western Pacific, and 2.4 × 10² m² s⁻¹ at 10 km and 1.8 × 10⁴ m² s⁻¹ at 100 km south of Japan. These empirically constrained coefficients provide sub-grid parameterization for coarse-resolution global pollutant transport models and demonstrate the field applicability of the new drifter system.1