• 한국수산과학회지
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• 제11권2호
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• pp.49-54
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• 1978

한국 동해안해역에서 하계에 출현하는 냉수괴의 생성기구를 해양화학적인 측면에서 검토한 결과를 요약하면 다음과 같다. 1. 동해연안의 냉수괴출현해역의 인산염과 용존산계의 특수한 관계를 조사한 결과 동해남부 연안해역인 감포부근 해역에서만 용승현상을 인정할 수 있었으나 그 이북 동해중부해역에서는 용승현상을 인정할 수 없었다. 2. $\sigma_t-O_2$ diagram에 의해 동해연안해역의 구성수괴를 분석하면 T-S diagram 으로는 구별하기 어려운 북한한류계수와 일본해고유냉수를 구별할 수 있었다. 3. 동해남부 연안해역을 제외한 동해중부 연안해역에 출현하는 냉수괴의 기원은 일본해고유냉수의 용승에 의한 것이 아니고, 북한한류가 안안을 따라 남하하는 현상 때문으로 보인다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 추계학술대회
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• pp.160-161
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• 2022

Hydrogen is bridge fuel with high energy content and environmentally friendly to satisfy the stringent IMO regulation relating to greenhouse gas (GHG) emissions. There is growing interest in hydrogen in numerous nations and regions illustrated by an extensive range of research and development in technology. Regarding maritime applications, researchers have recognized the utilization of hydrogen as a fuel for fuel cells, a device that converts the chemical energy of the fuel to electrical energy. Solid oxide fuel cell (SOFC), with high working temperature, is easy to combine with the waste heat recovery cycles/devices to increase output power and thermodynamic performances as well. Furthermore, the cold energy from liquid hydrogen supplied to SOFC can also be used to generate more power. In this study, we proposed a SOFC integrated system with the idea of combining the waste heat recovery from the SOFC exhaust stream and cold energy utilization from LH₂. The designation is aimed to target small-scale vessel which uses electric propulsion for short distances voyage.

• Structural Engineering and Mechanics
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• 제90권5호
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• pp.435-446
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• 2024

The use of cold-formed steel members is increasing day by day, especially in regions where earthquake effects are intensively experienced. Among cold-formed steel members (CFS), "channel" members are used more than other crosssectional members, especially in buildings or industrial structures. In recent years, several studies have been carried out on the axial load and flexural performance of these members under monotonic loading. In this study, CFS beam-column members were cyclically and monotonically loaded under combined axial load and biaxial bending moments, and their buckling behavior, load bearing capacity, stiffness, ductility, and energy absorption capacity were determined. For this purpose, monotonic and cyclic loading experiments were carried out on 30 CFS channel members at 15 different eccentricities. Then, material properties were determined by axial monotonic tensile and very low cycle fatigue tests for use in numerical studies. From the experimental results, the buckling modes, bearing capacities, ductility, stiffness, and energy absorption capacities of the members were obtained. The characteristics of the members were compared according to the stress state of the lips. According to the data obtained from the displacement transducer placed on the lips and on the back of the web, information about the buckling mode and curvature of the members was obtained. Finally, monotonic, and cyclic loading results were compared to determine the differences in the buckling behavior of the members.

• 터널과지하공간
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• 제25권2호
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• pp.144-154
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• 2015

암석시료에 응력이 가해질 경우 역학적 에너지가 대상 물체에 누적되고, 대상 암석에 한계응력 이상이 가해질 경우 시료의 파괴가 발생한다. 이 때 시료 내부에 저장되어 있던 역학적 에너지는 물리적 변형뿐만 아니라 빛, 열, 소리 등 다양한 형태의 에너지로 발산된다. 본 연구에서는 $-10^{\circ}C$ 저온 환경에서 섬록암, 현무암, 응회암을 대상으로 일축압축강도 시험과 점하중강도 시험을 수행하고, 이때 발생하는 온도 변화를 열적외선카메라를 이용해 측정하고 정량적으로 분석하였다. 파괴 직전 파괴면에 응력이 집중되어 온도가 상승하였고, 파괴 순간 축적된 에너지가 열에너지의 형태로 방출되며 파괴면의 온도가 급격히 상승하는 것이 감지되었다. 강도가 높고 신선한 섬록암과 현무암 시료의 온도 상승폭이 상대적으로 강도가 낮고 풍화된 암석인 응회암 시료의 온도 상승폭에 비해 더 크게 나타났다. 본 연구결과는 저온지역에 위치한 암반사면, 터널, 광산 내부의 응력 집중지점을 감지해 향후 발생 가능한 재해를 예방하는데 적용될 수 있으며, 지진예측을 위한 위성영상 분석에도 적용될 것으로 기대된다.

• 한국해양공학회지
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• 제22권2호
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• pp.42-49
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• 2008

Recently many countries have become interested in the development of cold or arctic regions. The construction of engineered structures in those regions demands an understanding of the deformation characteristics of frozen soil. However, an understanding of frozen soil behavior poses difficult problems owing to the complex interaction between the soil particles and the ice matrix. In this research, a series of laboratory tests was performed to investigate the variations in the unconfined compression strength and split tensile strength of weathered granite soil and mixed soil (standard sand and kaolinite) in 15 degrees below zero environments. In the frozen soil tests, specimens were prepared with various water and clay contents, and then the interrelationships between four factors (water content, clay content, unconfined compression strength, split tensile strength) were analyzed. The test results were summarized as follows; as the water content was increased, the unconfined compressive and split tensile strengths also increased in frozen soil. However as the clay content was increased, the unconfined compressive and split tensile strengths were lowered. In the case of frozen soil that contained little clay content, the strength decreased rapidly in mixed soil (standard sand and kaolinite) when the frozen specimen was broken. On the other hand, in the cases of mixed soil that contained a high clay content and weathered granite soil, the strength decreased relatively slowly.

• 소성∙가공
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• 제31권6호
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• pp.376-383
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• 2022

The potential damage region of a WC-Co cemented carbide die is investigated for cold forging process of a wheel-nut by numerical simulation with its chemical composition considered. Numerical simulation is utilized to calculate internal stress, especially for the WC-Co die, during the forging process. Finite element model is established, in which the elasto-plastic properties are applied to the work-piece of bulk steel, and elastic properties are considered for the lower die insert of the WC-Co alloy. This stress analysis enables to distinguish the potential damage regions of the WC-Co die. The regions from calculation are comparatively analyzed along with the crack area observed in the die after repetitive manufacturing. Effect of chemical composition of the WC-Co is also evaluated on characteristics of potential damage region of the die with variance of mechanical properties considered. Derived from Mohr-Coulomb fracture model, furthermore, a new stress index is presented and used for die stress analysis. This index inherently considers hydrostatic pressure and is then capable of deducing wide range of its distribution for representing stress state by modification of its parameter implying pressure sensitivity.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.314-314
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• 2023

Extreme climate events can have a large impact on human life by hampering social, environmental, and economic development. Global circulation models (GCMs) are the widely used numerical models to understand the anticipated future climate change. However, different GCMs can project different future climates due to structural differences, varying initial boundary conditions and assumptions about the physical phenomena. The multi-model ensemble (MME) approach can improve the uncertainties associated with the different GCM outcomes. In this study, a comprehensive rating metric was used to select the best-performing GCMs out of 11 CMIP5 and 13 CMIP6 GCMs, according to their skills in terms of four temporal and five spatial performance indices, in replicating the 21 extreme climate indices during the baseline (1975-2017) in South Korea. The MME data were derived by averaging the simulations from all selected GCMs and three top-ranked GCMs. The random forest (RF) algorithm was also used to derive the MME data from the three top-ranked GCMs. The RF-derived MME data of the three top-ranked GCMs showed the highest performance in simulating the baseline extreme climate which was subsequently used to project the future extreme climate indices under both the representative concentration pathway (RCP) and the socioeconomic concentration pathway scenarios (SSP). The extreme cold and warming indices had declining and increasing trends, respectively, and most extreme precipitation indices had increasing trends over the period 2031-2100. Compared to all scenarios, RCP8.5 showed drastic changes in future extreme climate indices. The coasts in the east, south and west had stronger warming than the rest of the country, while mountain areas in the north experienced more extreme cold. While extreme cold climatology gradually declined from north to south, extreme warming climatology continuously grew from coastal to inland and northern mountainous regions. The results showed that the socially, environmentally and agriculturally important regions of South Korea were at increased risk of facing the detrimental impacts of extreme climatology.

• 한국작물학회지
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• 제34권s02호
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• pp.34-44
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• 1989

우리나라의 벼안전재배는 기상환경에 의해서 크게 좌우된다. 그러므로 기상재해를 경감시키기 위한 신품종의 육성 및 재배법 연구는 매우 중요하다. 그중에서도 벼의 냉해는 그동안 여러번에 걸쳐 심한 피해를 가져다 주어 그 중요성이 확인되어 많은 연구가 실시되었다. 본 논문에서는 이와 같은 냉해의 발생원인과 기작을 살펴보고 그 경감대책을 종합하여 보다 더 효율적인 연구와 실질적인 재배의 기초자료로 활용하고저 한다. 1. 우리나라 벼 냉해 상습지는 전국적으로 1,709개소에 약 15,522ha에 분포하고 있다. 2. 벼유묘기 냉해는 발아불량, 적고현상, 고사 및 뜸묘의 발생 등으로 나타난다. 3. 영양생장기의 냉해는 활착불량으로 분얼수가 감소하여 단위면적당 수수가 적고, 생육지연 및 유수형성 지연으로 출수가 지연된다. 4. 생식생장 초기의 냉해는 지경 및 영화의 퇴화, 발육정지가 되고, 감수분열기에는 화분발육의 조해로 불념이 증가되고 수장이 단축되며 출수지연으로 수량감소에 큰 영향을 준다. 5. 출수 및 등숙기 냉해는 개화, 출수 지연으로 수분, 수정이 불량하며 이삭목의 추출불량, 등숙불량 및 쌀의 미질이 불량하게 된다. 이상과 같은 냉해를 경감시키기 위한 기술시책으로는 6. 중산간지 및 산간고냉지에 적용되며, 내냉성이 높은 품종육성 7. 밭못리 육묘와 ABA, 후치왕, 다찌에스 등의 생장조정제를 이용한 건묘육성 8. 냉수답이나 냉해상습지에는 토양개량 및 육기작 시용으로 보비로 튼튼한 벼생육을 가져 온다. 9. 냉해시에는 깊게 물대기와 냉수관개시에는 우회수로, 비닐튜브 등을 이용한 물온도 높여 주기 등 합리적인 물관리가 필요하다. 10. 각 지역의 최고, 평균, 최저온도를 기본으로 한 안전작기를 책정하여 적기에 적품종을 재배하여야 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제23권12호
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• pp.1543-1551
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• 2010

A major aim of cattle genome research is to identify candidate genes associated with meat quantity and quality through QTL analysis for application in the livestock industry. Therefore, this study focused on discovery of useful SNPs within the LOC534614 gene, containing 12273_165 SNP which is located on the same site as the QTL on chromosome 6, and evaluation of the association between SNP and body weight and cold carcass weight in Hanwoo (Korean cattle) As a result of a BLAST search of the NCBI web site, we discovered that the mRNA sequence of the LOC534614 gene was similar to that of the coiled-coil domain containing 158 (CCDC158) for dog and human. According to the direct DNA sequence from the CCDC158 gene, we identified 19 polymorphic SNPs within exons and their flanking regions. Among them, 17 polymorphic SNPs were selected for genotyping in Hanwoo (n = 476) and seventeen marker haplotypes containing 12273_165 SNP (frequency >0.1) were identified. As a result of the association between 17 polymorphic SNPs and Hanwoo (n = 476), g.8778G>A SNP in exon 6 was found to be a non-synonymous SNP, and was significantly associated with body weight and cold carcass weight (p<0.05). We discovered 19 polymorphic SNPs in the CCDC158 gene on the QTL region of BTA 6 in Hanwoo and identified that the g.8778G>A SNP was significantly associated with body weight and cold carcass weight (p<0.05), which causes an amino acid variation from valine to methionine. Furthermore, statistical analysis demonstrated that the CCDC158 gene is strongly associated with body weight and cold carcass weight in Hanwoo. In this regard, the g.8778G>A SNP in the CCDC158 gene can be useful as a positional candidate for body weight and cold carcass weight for marker-assisted selection in Hanwoo.

• 한국의류학회지
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• 제23권5호
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• pp.667-671
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• 1999

The purpose of this study was to determine the number of skin cold receptor in Korean adult as a part of the study to investigate thermal physiological characteristics of Korean. For this 10 healthy subjects were placed in a climatic chamber and received cold stimulation of 1$0^{\circ}C$ on skin surface of each measuring site with a thermo-stimulator. As a result of cold spot measurement we found 23 points/cm2 at face 13. points/cm2 at chest 16 points/cm2 at abdomen 11 points/cm2 at back 14 points/cm2 at upper arm 16 points/cm2 at forearm 18 points/cm2 at back of the hand 15 points/cm2 at thigh 8 points/cm2 at leg 12 points/cm2 at dorsum of foot 8 points/cm2 at sole of foot in male subjects and in female subjects we fund 18 points/cm2 at face 13 points/cm2 at forearm 11 points/cm2 at at back of the hand 8 points/cm2 at palm 9 points/cm2 at thigh 6 points/cm2 at leg 8 points/cm2 at dorsum of foot 2 points/cm2 at sole of foot. The distributions of cold spots varied in different regions of the body surface and was exceptionally dense in the facial skin. There were some differences among other researchers' results but the cause of those differences are not yet known those are due to individual or methodological difference.