• 우주기술과 응용
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• 제1권2호
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• pp.178-198
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• 2021

국내 태양우주환경 분야에서 널리 이용되는 자료와 모델의 이해와 활용도를 높이고, 세부 분야 간 공동연구의 기회의 장을 마련하고자, 최근 한국우주과학회 태양우주환경분과에서 국내 연구소와 대학을 중심으로 사용되는 태양우주환경 자료와 모델의 보유 및 활용에 대한 조사를 실시했다. 조사 결과를 크게 태양 및 행성간 공간, 자기권, 전리권의 세 분야로 나눠 정리하였고, 본 논문에서는 자기권 분야의 관련 자료와 모델을 소개한다. 자기권 연구의 특성 상 우주공간에서 지점관측을 위한 위성 개발과 운용에 투자가 많이 필요하여 국내 보유 자료는 다른 분야에 비해 상대적으로 적은 편으로 조사됐지만, 국내 지자기관측소를 통한 자기장 변화를 실시간으로 제공하고 있으며, 자기권 모델을 통해 꾸준한 연구를 수행 중이다. 본 논문에서는 자기권 분야 중 국내 위성자료를 이용한 연구들과 제 1원리 물리법칙에 바탕이 된 모델을 대표로 소개한다. 이번 조사 결과와 이를 정리한 논문이 우주과학 관련 자료에 대한 장기적이고 연속적인 관리에 대한 중요성을 인식하며, 우주과학 연구에 참여하는 다양한 인력들이 참조하여 국내에서 생산되고 있는 자료를 활용하여 국내 우주과학 자료의 위상을 높이는데 기여하기를 희망한다. 자료에 대한 조사 내용은 한국우주과학회 홈페이지에서 다운로드할 수 있다(http://ksss.or.kr/).

• 해양환경안전학회지
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• 제5권2호
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• pp.57-65
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• 1999

The in situ observations and the seawater analyses were conducted at all seasons from July 1996 to April 1999 for the purpose of describing the characteristics of seasonal variations of water quality in Mokpo harbour, Korea. Vertical stratification started to be formed in water column in spring, developed in summer and disappeared in fall. In summer, vertical density distribution of water column was found to be in stable structure with lower temperature and higher salinity of bottom water, and the vertical mixing of water between surface and bottom layers was restricted. In winter, however, surface water was found to be similar to bottom water in temperature and salinity, and water column was in unstable structure and in well-mixed condition between surface and bottom waters. The saturation percentage of dissolved oxygen(DO) in bottom water of inner part of Mokpo harbour at all seasons was shown to be decreased to the third grade or under the third grade of Korean standards of seawater quality. In particular, dissolved oxygen was oversaturated in surface water and undersaturated in bottom water in summer, due to stratification and organic pollution. The difference of DO concentration between surface and bottom waters was found to be greater in spring and summer than in fall and winter, due to stratification and photosynthesis of phytoplankton. The concentrations of chemical oxygen demand(COD) over the entire waters of Mokpo harbour were found to fluctuate from below the third grade to the first grade of Korean standards through all seasons and COD concentrations of same seasons were shown to be different year after year. In particular, in view of COD, the annual average seawater quality of Mokpo harbour was evaluated to be in third grade of Korean standards, due to organic pollution. The average COD of surface water was greater than that of bottom water in spring and summer, due to the autochthonous COD caused by production of phytoplankton in surface waters, while the average COD of surface water was similar to that of bottom water in fall and winter, due to the vertical mixing of water between surface and bottom layers.

• 대한원격탐사학회지
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• 제34권6_2호
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• pp.1261-1272
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• 2018

북극 지역의 대기 온도는 바다 및 해빙, 대기 사이의 에너지 교환에 큰 역할을 하므로 북극 대기 온도를 정확하게 파악하는 것은 중요하다. 하지만 현장 관측 자료들은 북극 대기 온도의 공간적인 분포를 나타내는 데에 한계가 있다. 따라서 본 연구에서는 부이(buoy) 자료와 Advanced Microwave Scanning Radiometer 2(AMSR2) 위성자료를 이용하여 기계학습 기반 여름철 대기 온도 추정 모델을 구축하였다. 기계학습으로는 random forest(RF) 및 support vector machine(SVM)을 사용하였으며, AMSR2 관측 시간에 따라 하루 두 번의 대기 온도를 추정하였다. 또한 추정된 대기 온도를 유럽 중기예보센터(European Centre for Medium-Range Weather Forecasts, ECMWF)의 ERA-Interim 재분석자료의 대기 온도와 공간 분포를 비교하였다. 교차 검증 결과 두 가지 기계학습 기법 모두 0.84-0.88의 $R^2$ 및 $1.31-1.53^{\circ}C$의 RMSE를 보였다. 공간적인 분포에서 IABP 부이 관측 자료가 존재하지 않는 바렌츠해(Barents Sea), 카라해(Kara Sea) 및 배핀만(Baffin bay) 지역에서는 기계학습 모델이 ERA-Interim 대기 온도에 비하여 과소 추정하는 경향을 보였다. 본 연구는 경험적인 북극 대기 온도 추정의 가능성과 한계점을 서술하였다.

• 한국해양환경ㆍ에너지학회지
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• 제4권3호
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• pp.3-15
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• 2001

목포항의 수질과 영양상태의 계절 변화를 구명하고 평가하기 위하여 1996년 8원부터 1999년 8월까지 3년간 현장 관측과 수질 분석을 실시하였다. 첫째, 투명도, 용존무기질소, 인산인 및 클로로필 a와 같은 수질 항목에 대하여 OECD 영양분류기준을 적용한 결과, 목포항 해수의 영양수준은 4계절 내내 중영양 내지 부영양 상태로 평가되었고, 특히 하계에는 부영양 상태로 나타났다. 둘째, 비록 목포항 수질은 화학적 산소요구량에 의하면 해역수질 환경기준의 2급수 내지 3급수로 평가되지만, 부영양화에 의한 오염지수를 산정한 결과에 의하면, 목포항은 수질이 악화되어 4계절 내내 3급수에도 미치지 못하는 것으로 나타났다. 셋째, 부영양도를 산정한 결과, 특히 하계 또는 추계에 목포항에서 적조 발생 잠재력이 높은 것으로 나타났다. 넷째, 해수중에 존재하는 인에 대한 질소의 평균원자비(N/P)를 살펴보면, 목포항에서 식물플랑크톤의 성장에 대한 제한 영양 인자는 질소라기보다는 인으로 나타났다

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3815-3819
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• 2012

The CD4+CD25+ regulatory T cell (Treg) is a special kind of T cell subset. Studies have showed that Treg cells are involved in a number of physiological processes and pathologic conditions such as autoimmune diseases, transplantation tolerance and cancer. Tregs with unique capacity for immune inhibition can impair anti-tumour immunity and help tumor cells to escape from immune surveillance. The aim of our study was to investigate whether Tregs are involved in hepatocellular carcinoma (HCC). A BABL/C mouse with HCC in situ model was established to evaluate the Treg existence in carcinoma tissues and the changes of Tregs in spleen using flow cytometry and immunohistochemistry methods. Granzyme B expression in carcinoma tissues was analyzed by immunohistochemistry to investigate the tumor local immune status.The proportion of CD4+CD25+/CD4+ spleen lymphocytes of tumor bearing mice ($18.8%{\pm}1.26%$) was found to be significantly higher than that in normal mice ($9.99%{\pm}1.90%$) (P<0.01 ). Immunohistochemistry of spleen tissue also confirmed that there was an increase in Treg in tumor-bearing mice, while in carcinomas it showed Treg cells to be present in tumor infiltrating lymphocyte areas while Granzyme B was rarely observed. Anti-tumour immunity was suppressed, and this might be associated with the increase of Tregs. Our observations suggest that the CD4+CD25+Treg/CD4+ proportion in spleen lymphocytes can be a sensitive index to evaluate the change of Tregs in hepatocellular carcinoma mice and the Treg may be a promising therapeutic target for cancer.

• 한국환경과학회지
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• 제32권5호
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• pp.285-301
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• 2023

This study analyzed characteristics of ozone (O₃) formation regimes in Busan over a period of recent five years (2015~2019) and compared the findings with those obtained in Seoul. We employed four observed variations: early morning commuting-hour (i.e., 06:00-09:00 LST) nitrogen dioxide (NO₂), peak-hour (i.e., 12:00-16:00 LST) O₃, 8-hour average O₃ (MDA8 O₃), and △O₃ (=O_{3_max}- O_{3_min}) in Busan and Seoul. In addition, the NO₂-O₃ relation was assessed to interpret which of NOx-limited or volatile organic compound (VOC)-limited was dominant. In Busan, the annual mean O₃ concentration was relatively higher than in Seoul, whereas there were fewer high-concentration days. The Pearson correlation coefficients (R) between Early morning-hour NO₂ and the Peak-hour O₃ was positive (but close to zero) in Busan and negative in Seoul. Likewise, the R between the Early morning-hour NO₂ and the △O₃ showed a relatively considerable positive correlation (R=+0.4~0.5)(R=+0.4~0.5) in Busan, while a weak positive correlation (R=+0.1~0.2) in Seoul. From this result, it can be inferred that the O₃ formation regime in Busan was intrepreted to be nearly neutral or relatively closer to the NO_x-limited regime than Seoul, while Seoul to the VOC-limited regime. The study findings imply that O₃ control strategies should be applied differently in Busan and Seoul. The results here were inferred from surface NO₂ and O₃ observations, and the varification studies based on in-situ VOCs measurements would be needed.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.306-309
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• 2007

Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO) includes global ocean surface heat flux data derived from satellite data and are used in many studies related to air-sea interaction. Recently latent heat flux data version 2 was constructed in J-OFURO. In version 2 many points are improved compared with version 1. A bulk algorithm used for estimation of latent heat flux is changed from Kondo (1975) to COASRE 3.0(Fairall et al., 2005). In version 1 we used NCEP reanalysis data (Reynolds and Smith, 1994) as SST data. However, the temporal resolution of the data is weekly and considerably low. Recently there are many kinds of global SST data because we can obtain SST data using a microwave radiometer sensor such as TRMM/MI and Aqua/AMSR-E. Therefore, we compared many SST products and determined to use Merged satellite and in situ data Global Daily (MGD) SST provided by Japan Meteorological Agency. Since we use wind speed and specific humidity data derived from one DMSP/SSMI sensor in J-OFURO, we obtain two data at most one day. Therefore, there may be large sampling errors for the daily-mean value. In order to escape this problem, multi-satellite data are used in version 2. As a result we could improve temporal resolution from 3-days mean value in version 1 to daily-mean value in version 2. Also we used an Optimum Interpolation method to estimate wind speed and specific humidity data instead of a simple mean method. Finally the data period is extended to 1989-2004. In this presentation we will introduce latent heat flux data version 2 in J-OFURO and comparison results with other surface latent heat flux data such as GSSTF2 and HOAPS etc. Moreover, we will present validation results by using buoy data.

• 천문학회보
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• 제37권2호
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• pp.101.2-101.2
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• 2012

Shocks are ubiquitous in astrophysical plasmas: bow shocks are formed by the interaction of solar wind with planetary magnetic fields, and supernova explosions and jets produce shocks in interstellar and intergalactic spaces. The global morphologies of these shocks are usually described by a set of magnetohydrodynamic (MHD) equations which tacitly assumes local thermal equilibrium, and the resulting Rankine-Hugoniot shock jump conditions are applied to obtain the relationship between the upstream and downstream physical quantities. While thermal equilibrium can be achieved easily in collisional fluids, it is generally believed that collisions are infrequent in astrophysical settings. In fact, shock widths are much smaller than collisional mean free paths and a variety of kinetic phenomena are seen at the shock fronts according to in situ observations of planetary shocks. Hence, both the MHD and kinetic equations have been adopted in theoretical and numerical studies to describe different aspects of the physical phenomena associated with astrophysical shocks. In this paper, we present the results of 3D relativistic particle-in-cell (PIC) simulations for ion-electron plasmas, with focus on the shock structures: when a jet propagates into an unmagnetized ambient plasma, a shock forms in the nonlinear stage of the Weibel instability. As the shock shows the structures that resemble those predicted in MHD systems, we compare the results with those predicted in the MHD shocks. We also discuss the thermalization processes of the upstream flows based on the time evolutions of the phase space and the velocity distribution, as well as the wave spectra analyses.

• Journal of Korean Neurosurgical Society
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• 제29권5호
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• pp.599-603
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• 2000

Objectives : In lumbar spine surgery it is observed that the ligamentum flavum(LF) is bilayered, and the inner layers can be left in situ to prevent peridural adhesion in open lumbar disc surgeries. The purposes of this study are to investigate ultrastructural differences between the inner and outer layer of lumbar LF by electron microscopic examination, and to see whether these differences are, if present, more prominent in chronic degenerative lumbar spinal disorders as compared with acute lumbar disc diseases. Methods : Biopsy specimens of LF were obtained from nine patients undergoing lumbar spine surgery, five of them for degenerative spinal stenosis and four for acute disc herniation. During the surgery the outer layers of LF were carefully dissected from the inner layer, and four pieces($1{\times}1{\times}1-mm$) of biopsy samples were made from each layer. These were examined with electron microscope for the morphologies and the contents of the elastic and the collagen fibers. Results : The outer layer of LF showed elastic fiber degeneration as evidenced and decreased fiber content, while the inner layer was relatively preserved in both cases of degenerative spinal stenosis and acute disc herniation. The ultrastructural changes of the layers were more evident in the outer layer. Conclusion : With these observations the authors believe that the LF degeneration may occur mainly in the outer layer, and that this fact may aid in making the rationale for using the inner layer as physiologic barrier to prevent peridural adhesion in open lumbar disc surgeries.

• Ocean and Polar Research
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• 제28권3호
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• pp.225-236
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• 2006

Seagrass meadows are considered as critical habitats for a wide variety of marine organisms in coastal and estuarine ecosystems. In many cases, studies on the spatial/temporal distribution of seagrass have depended on direct observations using SCUBA diving. As an alternative method fur studying seagrass distribution, an application of hydroacoustic technique has been assessed for mapping seagrass distribution in Dongdae Bay, on the south coast of Korea, in September 2005. Data were collected using high frequency transducer (420 kHz split-beam), which was installed with towed body system. The system was linked to DGPS to make goo-referenced data. Additionally, in situ seagrass distribution has been observed using underwater cameras and SCUBA diving at four stations in order to compare with acoustic data. Acoustic survey was conducted along 23 transects with 3-4 blot ship speed. Seagrass beds were vertically limited to depths less than 3.5m and seagrass height ranged between 55 and 90cm at the study sites. Dense seagmss beds were mainly found at the entrance of the bay and at a flat area around the center of the bay. Although the study area was a relatively small, the vertical and spatial distributions of the seagrass were highly variable with bathymetry and region. Considering dominant species, Zostera marina L., preliminary estimation of seagrass biomass with acoustic and direct sampling data was approximately $56.55g/m^2$, and total biomass of 104 tones (coefficient variation: 25.77%) was estimated at the study area. Hydroacoustic method provided valuable information to understand distribution pattern and to estimate seagrass biomass.