• 한국자동차공학회논문집
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• 제22권5호
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• pp.84-90
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• 2014

The aim of this paper is to investigate the application of solar energy in reducing cabin thermal load. When a vehicle is parked under the sun in summer, the interior temperature can reach up to $70^{\circ}C$ depending on the solar intensity. Solar power, one of the green energies, is used in automobile air conditioning systems, in order to operate the blower. The power supply of a blower's voltage has been used in a solar sunroof experiment. At the climate wind tunnel, cabin temperature changes were conducted with various operating modes of an air handling system and the preventilation parking conditions of several vehicles, outdoors, was also examined. The test results of the solar sunroof, 39.3W power and 14.1% efficiency were obtained. The thermal load behavior was analysed with the air handling system operating mode differently according to the cabin temperature. By simply operating the blower, average cabin temperature decreased between $5^{\circ}C{\sim}10^{\circ}C$ in those vehicles parked outdoors in summer. This reveals that cabin thermal comfort can be improved without consuming the vehicle's extra energy, and that the performance of the air-conditioning system is better than those currently found in vehicles. Moreover, fuel economy will be increased as a result of the reduction in the use of the air-conditioning system, and many other human advantages will be gained. Such advantages include minimized VOCs and a healthy cabin environment.

• 한국해양학회지:바다
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• 제24권4호
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• pp.509-518
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• 2019

다양한 표층 수온 자료를 통해 1979년부터 2018년 기간 동안의 가을철 동해 공간 평균 표층 수온이 태평양 순년 진동과 높은 상관관계를 나타내는 것을 확인하였다. 이 해역에서 제트류의 활동이 가장 강한 200 hPa에서의 바람과 동해 표층 수온의 회귀 분석 결과, 가을철 동해 표층 수온이 상승할 때 제트류의 중심축이 북상하면서 전반적으로 제트류가 약화하는 경향을 보이며, 동해 수온이 하강할 때는 제트류의 중심축이 남하하면서 제트류가 강화되는 경향을 보였다. 이러한 분석 결과는 제트류의 강도 변화와 중심축의 남북 진동이 동해 표층 수온과 태평양 순년 진동의 커플링과 관련되어 있음을 시사한다. 여름철의 약한 제트류와 겨울철 및 이른 봄철의 강한 동아시아 동계계절풍 효과는 동해와 태평양 순년 진동의 커플링이 가을철 외의 다른 계절에 잘 나타나지 않게 하는 이유로 생각해볼 수 있다.

• 대기
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• 제27권3호
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• pp.345-358
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• 2017

The decadal change in rainfall for Changma period over the South Korea in early-2000s is detected in this study. The Changma rainfall in P1 (1992~2002) decade is remarkably less than in P2 (2003~2013) decade. The much rainfall in P2 decade is associated with the increase of rainy day frequency during Changma period, including the frequent occurrences of rainy day with a intensity of 30 mm/day or more in P2 decade. This decadal change in the Changma rainfall is due to the decadal change of atmospheric circulation around the Korean Peninsula which affects the intensity and location of Changma rainfall. During P2 decade, the anomalous anti-cyclone over the south of the Korean Peninsula, which represents the expansion of the North Pacific high with warm and wet air mass toward East Asia, is stronger than in P1 decade. In addition, the upper level zonal wind and meridional gradient of low-level equivalent potential temperature in P2 decade is relatively strengthened over the northern part of the Korean Peninsula than in P1 decade, which corresponds with the intensification of meridional gradient between air mass related to the East Asian summer monsoon nearby the Korean Peninsula in P2 decade. The enhanced meridional gradient of atir mass during P2 decade is favorable condition for the intensification of Changma rainfall band and more Changma rainfall. The atmospheric conditions related to enhanced Changma rainfall during P2 decade is likely to be influenced by the teleconnection linked to the suppressed convection anomaly over the southern part of China and South China Sea in P2 decade.

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.303-314
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• 2004

In this paper we report some properties of inner magnetospheric structure inferred from the T01_s code, one of the latest magnetospheric models by Tsyganenko. We have constructed three average storms representing moderate, strong, and severe intensity storms using 95 actual storms. The three storms are then modelled by the T01_s code to examine differences in magnetic structure among them. We find that the magnetic structure of intense storms is strikingly different from the normal structure. First, when the storm intensity is large, the field lines anchored at dayside longitudinal sectors become warped tailward to align to the solar wind direction. This is particularly so for the field lines anchored at the longitudinal sectors from postnoon through dusk. Also while for the moderate storm the equatorial magnetic field near geosynchronous altitude is found to be weakest near midnight sector, this depression region expands into even late afternoon sector during the severe storm. Accordingly the field line curvature radius at the equator in the premidnight geosynchronous region becomes unusually small, reaching down to a value less than 500 km. We attribute this strong depression and the dawn-dusk asymmetry to the combined effect from the enhanced tail current and the westward expansion/rotation of the partial ring current.

• 천문학회보
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• 제35권1호
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• pp.34.2-34.2
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• 2010

Cosmic rays registered by Neutron Monitors on the surface of the Earth are believed to be coming from outer space, and sometimes also from the exotic objects of the Sun. Ground level enhancement (GLE) is the sudden, sharp and short-lived increase in cosmic rays originated from the Sun. Since GLE is the signature in solar cosmic ray intensity, different solar factors erupted from the Sun can be responsible for causing it. In this context, an attempt has been made to determine quantitative relationships of GLEs > 5% with simultaneous solar, interplanetary and geophysical factors from 1997 through 2006 thereby searching the perpetrators which seem to be causing them. The study has revealed that solar flares are stronger ($0.71{\times}10-4$ w/m2) during GLE peaks than the solar flares ($1.10{\times}10-5$ w/m2) during GLE non-peaks and backgrounds. On the average, the solar wind plasma velocity and interplanetary magnetic field are found stronger during the GLE peaks than the GLE non-peaks and backgrounds indicating that the solar flares, in conjunction with interplanetary shocks, sometimes may cause GLE peaks. Direct proportionality of GLE peaks to simultaneous solar energetic particle (SEP) fluxes imply that the GLE peaks may often be caused by SEP fluxes. Although the high intensity of SEP fluxes are also seen extended few minutes even after GLE peaks, the mean (373.62 MeV) of the GLE associated SEP fluxes is much stronger than the mean (10.35 MeV) of the non-GLE associated SEP fluxes. Evidences are also supported by corresponding SEP fluences that the the mean fluence (${\sim}5.32{\times}107/cm2$) across GLE event was more intense than the mean fluence (${\sim}2.53{\times}106/cm2$) of SEP fluxes across non-GLE event.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제26권1호
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• pp.15-29
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• 1998

The numerical simulation of heavy precipitation event occurred in the central Korean Peninsula on July 26-28, 1996 was performed using the fine mesh model. ARPS (Advanced Regional Prediction System) developed by the CAPS (Center for Analysis and Prediction of Storms). Usually, the heavy rainfalls occurred at late July in the Korean Peninsula were difficult to predict, and showed very strong rainfall intensity. As results, they caused a great loss of life and property. As it usual, this case was unsuccessful to predict the location of rain band and the precipitation intensity with the coarse-mesh model. The same case was, however, simulated well with fine-mesh storm-scale model, ARPS. Moisture band at 850 hPa appeared along the Changma Front in the area of China through central Korea passed Yellow Sea. Also the low-level jet at 700 hPa existed in the Yellow Sea through central Korea and they together offered favorable condition to induce heavy rainfall in that area. The convective activities developed to a meso-scale convective system were observed at near the Yangtze River and moved to the central Korean Peninsula. Furthermore, the intrusion of warm and moist air, origninated from typhoon, into the Asia Continent might result in heavy rainfall formation through redistribution of moisture and heat. In the vertical circulation, the heavy rainfall was formed between the upper- and low-level jets, especially, the entrance region of the upper-level jet above the exit the region of the low-level jet. The low level convergence, the upper level divergence and the strong vertical wind were organized to the very north of the low level jet and concentrated on tens to hundreds km horizontal distance. These result represent the upper- and low-level jets are one of the most important reasons on the formation of heavy precipitation.

• 대기
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• 제30권1호
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• pp.17-30
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• 2020

KMA performed the special observation program to provide information about severe weather and to monitor typhoon PRAPIROON using the ship which called the Gisang 1 from 29 June 2018 to 4 July 2018 (UTC). For this period, upper-air was observed 21 times with 6 hour intervals using rawinsonde in the Gisang 1. We investigated the impact of upper-air observation data from the Gisang 1 on the performance of the operational convective scale model (we called LDAPS). We conducted two experiments that used all observation data including upper-air observation data from the Gisang 1 (OPER) and without it (EXPR). For a typhoon PRAPIROON case, track forecast error of OPER was lower than EXPR until forecast 24 hours. The intensity forecast error of OPER for minimum sea level pressure was lower than EXPR until forecast 12 hours. The intensity forecast error of OPER for maximum wind speed was mostly lower than EXPR until forecast 30 hours. OPER showed good performance for typhoon forecast compared with EXPR at the early lead time. Two precipitation cases occurred in the south of the Korean peninsula due to the impact of Changma on 1 July and typhoon on 3 July. The location of main precipitation band predicted from OPER was closer to observations. As assimilating upper-air data observed in the Gisang 1 to model, it showed positive results in typhoon and precipitation cases.

• 한국유체기계학회 논문집
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• 제8권4호
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• pp.27-38
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• 2005

The present study investigated the effect of relative position of the blade on blade surface heat transfer. The experiments were conducted in a low speed wind tunnel with a stationary annular turbine cascade. The test section has a single turbine stage composed of sixteen guide vanes and blades. The chord length of the blade is 150 mm and the mean tip clearance of the blade is $2.5\%$ of the blade chord. The Reynolds number based on blade inlet velocity and chord length is $1.5{\times}105$ and mean turbulence intensity is about $3\%$. To investigate the effect of relative position of blade, the blade at six different positions in a pitch was examined. For the detailed mass transfer measurements, a naphthalene sublimation technique was used. In general, complex heat transfer characteristics are observed on the blade surface due to various flow characteristics, such as a laminar flow separation, relaminarization, flow acceleration, transition to turbulence and tip leakage vortices. The results show that the blade relative position affects those heat transfer characteristics because the distributions of incoming flow velocity and turbulence intensity are changed. Especially, the heat transfer pattern on the near-tip region is significantly affected by the relative position of the blade because the effect of tip leakage vortex is strongly dependent on the blade position. On the pressure side, the effect of blade position is not so significant as on the suction side surface although the position and the size of the separation bubble are changed.

• 한국지구과학회지
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• 제37권6호
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• pp.359-372
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• 2016

The time-series of Walker circulation index (WCI) in this study shows the strengthening of the Walker circulation in recent years. To further understand the large-scale features related to the WCI strengthening, a difference between the averaged meteorological variables in two time periods 1999-2013 and 1984-1998 is analyzed. The difference in 850 hPa stream flows between the two periods shows that the anomalous easterlies (anomalous trade wind) are dominant due to the strengthening of anomalous anticyclonic circulations at the subtropical Pacific of both hemispheres. The difference between the averaged zonal atmospheric circulations over $5^oS-5^oN$ in the two periods confirms that upward flows are strengthened at the tropical western Pacific and downward flows are strengthened at the tropical central and eastern Pacific in recent years. It matches the WCI strengthening in recent years. The time-series of tropical cyclone (TC) genesis frequency from July to September shows that a mean TC genesis frequency from 1999-2013 decreases compared to that of the time period 1984-1998. The monsoon trough in the period 1984-1998 was located in the further east direction and stronger than that in the period 1999-2013. TCs in the recent period that are generated in further west than TCs in the past period moved from the west. Thus, the TC intensity along the coasts in East Asia becomes weaker in recent period. The intensification of Walker circulation in recent years is related to the weaker TC intensity in East Asia through strengthened anomalous anticyclones at the subtropical western Pacific.

• 한국산림과학회지
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• 제94권6호
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• pp.481-487
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• 2005

이 연구에서는 지표화 중심의 산불확산예측 알고리즘을 기반으로 GIS 환경에서 운용이 가능한 지표화 확산예측모델을 개발하였다. 이 모델은 지형, 연료, 기상 등 산불환경인자를 분석하고 입력하는 부분과 시간에 따라 확산속도, 화선에서의 산불강도, 연소면적을 예측하는 지표화 확산예측 부분, 마지막으로 예측결과를 사용자에게 제시하는 출력 부분으로 구성되었다. 산불확산속도를 계산하기 위해서 산불행동에 영향을 미치는 산불환경인자중에서 지형인자는 경사, 기상인자는 풍속, 풍향, 실효습도를 고려하였다. 또한 연료인자는 수치임상도를 이용하여 연료깊이, 연료량, 소화습도를 계산할 수 있는 연료모듈을 개발하여 입력되도록 하였다. 연료습도는 실효습도, 최고온도, 강수량, 일일 적산량의 함수관계로 추정하였다. 모델을 2002년 청양에서 발생한 산불에 적용한 결과 확산속도에 대해 61%의 일치도를 보였다.