• 대기
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• 제28권4호
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• pp.383-392
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• 2018

This study investigates synoptic characteristics of cold surges over South Korea during winter season (December-February). A total of 63 cold events are selected by quantile regression analysis using daily mean temperature observations from 11 KMA stations for 38 years (1979/80-2016/17). Large-scale pressure pattern during the cold surges is well characterized by high over Siberia and low over Aleutian regions, which elucidates cold advection over the Korean peninsula. However, the large-scale pattern cannot successfully explain the observed sudden decrease of temperature during the cold surges. Composite analyses reveal that a synoptic-scale cyclone developing over the northern Japan is a key feature that significantly contribute to the enhancement of cold advection by increasing pressure gradient over the Korean peninsula. Enhanced sensible and latent heat fluxes are observed over the southern ocean of Korea and Japan during the cold surges due to temperature and humidity differences between the near surface and the lower atmosphere over the ocean. The evaporated water vapor transported toward the center of the surface cyclone and condenses in the lower-to-middle troposphere. The released energy likely promotes the development of the surface cyclone by inducing positive PV near the surface of the heating region.

• 한국수산과학회지
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• 제41권4호
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• pp.294-300
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• 2008

Abnormal cooling of the Korean East Sea Water(KESW) in the East Sea before and after the 1982-1983 and 1997-1998 ENSO events is examined using bimonthly routine observation data from the National Fisheries Research and Development Institute of Korea for the period 1965 to 2002. The KESW, which occupies roughly a region between the Korean Peninsula and west of approximately $131^{\circ}E$, showed extreme cold-state years(1981 and 1996) prior to the two strongest ENSO events of the last half-century. Inter-annual bimonthly mean anomalies at 100 m in the KESW region were $-3.10^{\circ}C\;and\;-3.41^{\circ}C(SD=1.4^{\circ}C)$ in 1981 and 1996, respectively. These results suggest that extreme cooling of the KESW may be a prelude to very strong ENSO events through large-scale teleconnections.

• 한국지구과학회지
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• 제36권2호
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• pp.190-197
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• 2015

남극 브랜스필드 해협의 동부분지로부터 획득한 GC08-EB01 코어퇴적물의 고해상 엽층리로부터 규조를 이용하여 고기후변화를 연구하였다. 규조 정량 분석의 결과 규조 개체수 농도는 $0.4-4.2{\times}10^8g^{-1}$로 매우 풍부하게 산출되었으며, 엽층리는 생물기원의 규조가 풍부한 층과 육성기원 퇴적물이 풍부한 층으로 구분된다. 규조 엽층리는 Corethron crilophilum, Eucampia antarctica, Fragilariopsis curta, F. kerguelensis, Odontella weissflogii, Proboscia inermis, R. styliformis, Thalassiosira antarctica와 Chaetoceros resting spores 등의 번성이 특징적이며, 육원성 엽층리에서는 규조 군집이 혼합되어 나타나는 것이 특징이다. 홀로세 후기 동안 Fragilariopsis curta+F. cylindrus)/Thalassiosira antarctica의 산출 수직 분포비가 급격히 증가하는 구간은 해빙의 확장을 지시하며, 연구 코어 GC08-EB01 코어퇴적물이 퇴적되는 동안 적어도 5번의 한랭기가 있었음을 알려준다.

• 대기
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• 제29권4호
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• pp.463-480
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• 2019

This study classified heavy rain types from K-means clustering for the hourly relationship between rainfall intensity and cloud top height over the Korean peninsula, and then examined their statistical characteristics for the period of June~August 2013~2018. Total rainfall amount of warm-type events was 2.65 times larger than that of the cold-type, whereas the lightning frequency divided by total rainfall for the warm-type was only 46% of the cold-type. Typical cold-type cases exhibited high cloud top height around 16 km, large reflectivity in the upper layer, and frequent lightning flashes under convectively unstable condition. Phenomenally, the cold-type cases corresponded to cloud cluster or multi-cell thunderstorms. However, two warm-type cases related to Changma and typhoon were characterized by heavy rainfall due to long duration, relatively low cloud top height and upper-level reflectivity, and the absence of lightning under the convectively neutral and extremely humid conditions. This study further confirmed that the forecast skill of rainfall could be improved by applying correction factor with the overestimation for cold-type and underestimation for warm-type cases in the Local Data Assimilation and Prediction System (LDAPS) operational model (e.g., BIAS score was improved by 5%).

• 한국대기환경학회지
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• 제25권6호
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• pp.481-492
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• 2009

The characteristic of cold water by upwelling in the southeast of the Korean Peninsula and the effect of sea breeze in this region are investigated. The coastal upwelling around the southeast coast of the Korea Peninsula is analyzed by using Coastal Oceanographic Data statistical analyses for 5 years were carried out. The period of an cold water event, on the average, was observed southwesterly wind events. The analysis suggests that strong and persistent southwesterly winds in period of an cold water play an important role of bring the moisture to the surface, generating persistent cyclone as jangma. In order to investigate the effect of cold water on sea breeze, we considered two case. First, Exp. 1 is not occurred coastal upwelling on sea breeze. Second, Exp. 2 is occurred cold water on sea breeze. Two experiments were completed separately to the effects of cold water by upwelling. The results show the sea breeze is stronger in Exp. 2, when the cold water occurs, and weaker in Exp. 1, when there is no cold water. In order to verify the effect of the sea breeze on the cold water by upwelling, on the intensification and change of direction of the prevailing wind, the sea breeze effectively intensify cold water condition.

• Korean Journal of Acupuncture
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• 제29권3호
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• pp.421-430
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• 2012

Objectives : We investigated the incidence rate and type of adverse events associated with RCTs(Randomized Controlled Trials) of acupuncture and moxibustion. Methods : This study included 949 patients who received acupuncture or moxibustion or usual care from 8 RCTs. We collected data including gender and age of patients, intervention, treatment frequency and type of adverse events in clinical trials from their case report forms. Results : Among the 949 patients, 83 patients(8.7%) suffered at least one adverse event throughout the clinical trials. Types of adverse event in acupuncture & moxibustion clinical trials are common cold, skin changes, pain, dizziness, bruise, gastrointestinal diseases, changes of blood chemistry, burn. Adverse events were significantly correlated to patients' age, intervention, body mass index and treatment group. Conclusions : A Guide-line for collecting and managing adverse events of acupuncture & moxibustion clinical trials are needed.

• 한국지구과학회지
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• 제26권6호
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• pp.560-572
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• 2005

이 연구에서는 1979년부터 1999년까지 21년 동안에 한반도 겨울철 한파와 관련된 대기 순환 및 열원$(Q_1)$의 분포 특성을 조사하였다. 한파 발생 빈도는 1년간 약 1개로 나타났으며, 1989년을 중심으로 전반기에 전체의 $60\%$가 발생하였다. 한파 발생 동안 하층의 대기 순환 패턴은 평년에 비해 서고동저형의 기압 패턴이 더 뚜렷하며, 상층에서도 한반도에 기압골의 영향이 더 강하게 나타난다. 한파가 발생하는 동안에 한반도 부근의 기온 하강 패턴은 바이칼호 부근의 기온 패턴과 반대로 나타나며, 기온의 연직 구조에서도 400 hPa을 기준으로 하층과 상층의 기온 편차는 반대로 나타난다. 열원에 대한 분석은 한파 발생 시 한랭 이류에 의한 냉각은 하강 운동에 의한 단열 승온에 의해 균형을 이룬다는 것을 보여주는데, 이것은 한랭 핵의 이동이 열흡수원의 이동 경로와 연관되어 있음을 나타낸다. 따라서 한파의 유지 기작을 이해하고 한파를 예측하기 위해서는 열원 그리고 열흡수원의 이동 기작이 밝혀져야 할 것이다.

• Structural Engineering and Mechanics
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• 제49권2호
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• pp.237-259
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• 2014

Wind-induced failure around screwed connections has been documented in roof and wall cladding systems made with steel sheet cold-formed panels during high wind events. Previous research has found that low cycle fatigue caused by stress concentration and fluctuating wind loads is responsible for most such failures. A dynamic load protocol was employed in this work to represent fatigue under wind effects. A finite element model and fatigue criteria were implemented and compared with laboratory experiments in order to predict the fatigue failure associated with fluctuating wind loads. Results are used to develop an analytical model which can be employed for the fatigue analysis of steel cold-formed cladding systems. Existing three dimensional fatigue criteria are implemented and correlated with fatigue damage observed on steel claddings. Parametric studies are used to formulate suitable yet simple fatigue criteria. Fatigue failure is predicted in different configurations of loads, types of connections, and thicknesses of steel folded plate cladding. The analytical model, which correlated with experimental results reported in a companion paper, was validated for the fatigue life prediction and failure mechanism of different connection types and thicknesses of cold-formed steel cladding.

• 한국습지학회지
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• 제10권2호
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• pp.143-153
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• 2008

본 논문의 목적은 ENSO의 영향에 의한 우리나라 강우의 확률빈도와 공간분포 특성을 분석하는 것이다. 따라서 우리나라 기상관측소의 강우량 자료를 Warm(El Nino), Cold(La Nina), Normal 에피소드에 따라 기간별로 분류하였다. 또한 이렇게 분류한 자료는 Markov Chain 모형을 이용하여 100년의 자료로 모의 발생하였고 에피소드별로 빈도분석을 실시하였다. 빈도분석 결과 에피소드에 따라 각 기상관측소별로 강우의 크기에 영향을 미치고 있음을 알 수 있었다. 또한 군집분석을 실시하여 각 에피소드의 공간적인 영향에 대해서 분석하였다. 결과적으로 Warm(El Nino), Cold(La Nina) and Normal 에피소드로 대표되는 ENSO는 우리나라 강우의 확률빈도과 공간분포에 크게 영향을 미치는 것으로 파악되었다.

• Ocean and Polar Research
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• 제25권4호
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• pp.617-623
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• 2003

Organisms living in the Arctic and Antarctic regions are exposed to strong constraints, of which temperature is a driving factor. Evolution has led to special adaptations, some with important implications at the biochemical, physiological, and molecular levels. The northern and southern polar oceans have very different characteristics. Tectonic and oceanographic events have played a key role in delimiting the two polar ecosystems and influencing evolution. Antarctica has been isolated and cold longer than the Arctic; its ice sheet developed at least 10 million years earlier. As an intermediate system, the Arctic is a connection between the more extreme, simpler Antarctic system and the very complex temperate and tropical systems. By studying the molecular bases of cold adaptation in polar fish, and taking advantage of the information available on hemoglobin structure and function, we analysed the evolutionary history of the ${\alpha}\;and\;{\beta}globins$ of Antarctic and Arctic hemoglobin using the molecular clock hypothesis as a basis for reconstructing the phylogenetic relationships among species.