• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.139-151
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• 2017

This paper presents an overview of deep space orbit determination software (DSODS), as well as validation and verification results on its event prediction capabilities. DSODS was developed in the MATLAB object-oriented programming environment to support the Korea Pathfinder Lunar Orbiter (KPLO) mission. DSODS has three major capabilities: celestial event prediction for spacecraft, orbit determination with deep space network (DSN) tracking data, and DSN tracking data simulation. To achieve its functionality requirements, DSODS consists of four modules: orbit propagation (OP), event prediction (EP), data simulation (DS), and orbit determination (OD) modules. This paper explains the highest-level data flows between modules in event prediction, orbit determination, and tracking data simulation processes. Furthermore, to address the event prediction capability of DSODS, this paper introduces OP and EP modules. The role of the OP module is to handle time and coordinate system conversions, to propagate spacecraft trajectories, and to handle the ephemerides of spacecraft and celestial bodies. Currently, the OP module utilizes the General Mission Analysis Tool (GMAT) as a third-party software component for high-fidelity deep space propagation, as well as time and coordinate system conversions. The role of the EP module is to predict celestial events, including eclipses, and ground station visibilities, and this paper presents the functionality requirements of the EP module. The validation and verification results show that, for most cases, event prediction errors were less than 10 millisec when compared with flight proven mission analysis tools such as GMAT and Systems Tool Kit (STK). Thus, we conclude that DSODS is capable of predicting events for the KPLO in real mission applications.

• 한국전자파학회지:전자파기술
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• 제4권2호
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• pp.4-10
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• 1993

이동통신에서, 전파경로는 이동국의 위치변동때문에 시간 및 공간에 따라 변한다. 전파경로 손실은 주 파수와 거리뿐만 아니라 안테나 높이, 지형구조와 인위적 환경에 따라 탄라지브로 이동 전파신호의 전파 경로손실을 예측하기는 매우 어렵다. 본 고에서는 대전 및 서울 지역에서 전계강도를 측정하여 단구간 중앙치,500m 거리별 평균치 및 표준 편차를 산출하여 분석하였다. 분석 결과, 경로손실 특성이 예측모텔과 유사하였으며, 특히 단구간 중앙치 는 기지국 안테나 높이, 지형구조와 인위적 환경에 의존하며, 표준편차는 2-1OdBuV사이에 있음을 알 수 있다.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.5-11
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• 2011

In this study, the effect of cone angle of seven-hole probe on the accuracy of measured flow angle and velocity has been investigated. The seven-hole probe consisted of seven 1mm OD stainless inner tubes and one 3mm ID stainless tube. Six cone angles of $45^{\circ}$, $60^{\circ}$, $75^{\circ}$, $90^{\circ}$, $105^{\circ}$ and $120^{\circ}$ were tested. Calibrations of the seven-hole probes were conducted within ${\pm}60^{\circ}$ range with the interval of $5^{\circ}$. Analysis results show that the effect on the cone angle was not significant on the accuracy of the measured flow angle, pressure, and velocity. However, the data reduction method had more effect on the measurement accuracy.

• 동의생리병리학회지
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• 제20권2호
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• pp.358-364
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• 2006

To investigate the possible mechanism of Drynariae Rhizoma extracts as a candidate of anti-cancer drug, I examined the effects of Drynariae Rhizoma extracts on the apoptosis of U937 cell line. MTT assay, flow cytometric analysis, SDS-polyacrylamide gel electrophoresis, Western blot analysis, and RT-PCR were performed. Drynariae Rhizoma extracts treatment reduced the cell viablilty of U937 cells in a dose-dependent manner, which was associated with induction of apoptotic cell death. Drynariae Rhizoma extracts treatment also reduced the levels of Bcl-xL anti-apoptotic protein expression and increased the levels of caspase-3, p53, pro-apoptotic protein, in U937 cells. RT-PCR data revealed that the level of bcl-2, bcl-xL mRNA expressions decreased in a dose-dependent manner. These findings suggest that Drynariae Rhizoma extracts may have induction of apoptotic cell death via regulation of several growth regulatory gene products. The abbreviations used are: FBS, fetal bovine serum; PBS, phosphate buffered saline; PI, propidium iodide; OD, optical density; DiOC6, 3,3-dihexyloxa carbcyanine iodide; MTT, 3 [4-5-dimethylthiazol-2-yl] -2-diphenyltetrazolium bromide.

• 대한의생명과학회지
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• 제13권4호
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• pp.341-347
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• 2007

Streptococcus mutans, one of a major causal agents of dental caries, is component of the dental plaque and produces various organic acids such as lactic acid as the end-product of glycolysis. In this study, we isolated S. mutans from Korean children with caries and also investigated the expression of protein under acid stress. S. mutans was identified at the species level using a 16S ribosomal DNA sequencing comparison method. The primer specificity was tested on eleven S. mutans strains isolated from Korean children with caries. The data showed that eleven strains are S. mutans. At treatment of concentration of 20 mM lactic acid in the mid-log phage, K-7 exhibited the highest maximum culture OD compared with those of other groups. As a consequence, we examined the expression of protein under 20 mM lactic acid stress using S. mutans K-7. The results of 2D gel electrophoresis by image analysis showed that thirteen proteins are up-regulated under the stress. Further study is being focused on amino acid analysis by mass spectrometry in order to analyze those spots.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.210-218
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• 1998

Experimental results for forced convection condensationof Refrigerant-22 and ternary Refrigerant-407c(HFC-32/125/134a 23/25/52 wt%) considered as a substitute R-22 inside horizontal micor-fin tubes are presented. The test section was horizontal double-tubed counterflow condenser with a length 4000 mm micro-fin tube having 9.53 mm OD., 0.2 mm fin height and 60 fins. The refrigerants R-22 and R-407c were cooled by a coolant circulated in a surrounding annulus. The range of parameters of mass velocity was varied from 102.1 to 301.0kg/($\textrm{m}^{2}.s$) with inlet quality 1.0. Both refrigerant R-22 and its alternative refrigerant R-407c were tested within the same range of parameters. At the given experimental conditions for R-22 and R-407c the pressure drops for R-407c were considerably higher than those for R-22 at micro-fin tubes. Over the mass velocity range tested the PF(penalty factor)was lower than the increasing ratio of heat transfer area by fins. Based on the data correlation was proposed for predicting the frictional pressure drops for R-22 and R-407c for a duration of condensation inside a horizontal micro-fin tube.

• 항공우주기술
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• 제10권1호
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• pp.167-174
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• 2011

본 논문에서는 자동으로 GPS 원시데이터를 이용한 정밀궤도를 결정하는 시스템의 개발에 대해 기술하였다. 수 m 이상의 궤도결정 정밀도를 요구하는 일상적인 궤도데이터 처리 과정에 비해 1m ($1{\sigma}$) 혹은 서브미터 이하의 정밀한 궤도를 요구하는 궤도데이터 처리에는 보다 복잡한 처리과정을 요구한다. 본 논문에서는 정밀궤도결정을 자동으로 처리하기 위한 시스템 구성 및 시험결과에 대해 기술하였다. 구현된 정밀궤도결정 자동화 시스템은 위성관제를 위한 비행역학시스템의 일부로써 활용할 수 있으며, 저자에 의해 기존에 개발된 궤도운용 자동처리 시스템과 연계하여 다중 위성 정밀궤도결정 시스템으로 응용이 가능하다.

• Journal of Advanced Marine Engineering and Technology
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• 제18권4호
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• pp.53-61
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• 1994

An experimental study on heat pump cycle systematizing characteristics for non-azeotropic refrigerant mixtures of R-22+R-114 was reported. Data were obtained under steady state condition at the ranges of parameters, 550- 2, 170kcal/h, 670-2, 990kcal/h, 24-71kg/h, and 0-1, for as cooling capacity, heating capacity, mass 25, 50, 75, and 100 per cent of R-22 by weight fraction for R-22+R-114 mixtures. The results shown that the C.O.P of the 50wt% of R-22 mixture was considerably larger than for pure R-22 and other weight fraction of R-22 mixtures, but the compression power of the 25wt% of R-22 was lower than that of the pure R-22 and the other weight fraction of R-22 mixtures. The hightest value of cooling capacity was obtained at the conditions of evaporating temperature 5.deg.C and R-22 50wt% mixture. In general, with an increase in the R-22 weight fraction for fixed values of the other parameter, the cooling capacity increased at first, obtained a maximum, and then decreasd. This verified the importance of accurate weight fractions od refrigerant mixtures in the heat pump cycle.

• 한국치위생학회지
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• 제13권5호
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• pp.787-795
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• 2013

Objectives : The aim of the study is to investigate the possible influences of health behaviors and oral symptoms on subjective oral health status and to provide basic data for the development of oral health education programs. Methods : Subjects were 274 nursing home workers in Jeollabukdo, Korea. A self- reported survey was carried out. Results : Eighty four persons (30.7%) subjectively perceived their subjective oral health was good in the meanwhile forty nine persons (17.9%) reported poor oral health status. Health behaviors had much influence on their subjective oral health status. Good subjective oral health status coincided with quitting od smoking and drinking alcohol. Periodontal diseases and dental caries, and tooache had bad influences on subjective oral health status. Conclusions : Quitting program for smoking and drinking alcohol will make the nursing home workers in good healthy oral health status.

• 한국지형학회지
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• 제20권1호
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• pp.75-83
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• 2013

해안지역의 인위적 간섭은 토사의 생산 및 유출에 의해 지형적인 변동을 유발한다. 더욱이 해안변동을 안정화시키기 위한 구조물의 설치가 다른 지역의 지형을 변화시키는 요인이 되기도 한다. 그러나 대부분 해안지역에 대한 토사 유출자료는 구축되어 있지 않은 실정이다. 본 연구는 장기적인 해안변동 경향, 해안변동의 주요 인자인 토사유출의 정량적인 평가 방안, 그리고 이를 고려한 접속도로의 설계하중에 영향을 미치는 요소에 대해 적절한 방향을 제시하고자 한다.