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RISS 인기검색어
- 검색키워드
- 저자 : 김준(Jhoon Kim) (검색결과 40 건)
- 무료
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김준(Jhoon Kim),국봉재(B. J. Kook),문경정(K. J. Moon),이재화(J. H. Lee),구자호(J. H. Koo),박상서(S. S. Park),이효근(H. K. Lee) 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.3
외나로도의 기상발사기준은 발사체의 발사의 성공을 좌우할 수 있는 중요한 요소이다. 발사의 실패는 특히 발사대를 이탈하는 때로부터의 초기시간대에 거의 집중되어 있기 때문에 이 시기의 기상조건이 매우 중요하다. 과거 발사 운용과정에서 발사기상기준은 예측자료와 기본 바람자료만을 국한해서 사용하였지만, 발사체는 수직비행을 하므로 국지적인 낙뢰의 유발을 일으킬 수 있어 낙뢰자료가 필수적이며, 로켓의 자세제어와 안정성을 위해 바람의 바람 전단(Shear), 그 외에 낙뢰, 온도, 시정의 연직 분포가 중요하게 된다. 현재 외나로도에서는 이러한 기상자료가 구축되는 초기단계이지만, 외나로도 주변 지역 기상자료를 이용하여 우주센터 주변의 발사기상기준을 수립하였다 이러한 기상기준은 향후 외나로도 지역의 관측 자료 수집을 통한 지속적인 보완이 필요하다. Weather launch criteria of launch at Oenarodo Space Center is important for the successful launch operation. In particular, most of the launch failure occurs during the period of separation from the launch pad, thus meteorological condition is critical at this phase. In earlier days, the weather launch criteria adopted wind and forecast data for the launch operation. Nevertheless, the control of position and stability require other meteorological components such as vertical wind shear, lightning, temperature and visibility, because the launch vehicle is moving mostly vertically. We analyze these meteorological components by using the observed data at KMA at neighboring Oenarodo to determine the weather launch criteria. These criteria need further refinements through long-term observation.
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김준(Jhoon Kim),박상서(Sang-Seo Park),문경정(Kyung-Jung Moon),구자호(Ja-Ho Koo),이윤곤(Yun-Gon Lee),Koji Miyagawa,조희구(Hi-Ku Cho) 한국기상학회 2007 대기 Vol.17 No.4
Global Environment Laboratory at Yonsei University in Seoul (37.57˚N,126.95˚E) has carried out the ozone layer monitoring program in the framework of the Global Ozone Observing System of the World Meteorlogical Organization (WMO/GAW/GO3OS Station No. 252) since May of 1984. The daily measurements of total ozone and the vertical distribution of ozone amount have been made with the Dobson Spectrophotometer (No.124) on the roof of the Science Building on Yonsei campus. From 2004 through 2006, major parts of the manual operations are automated in measuring total ozone amount and vertical ozone profile through Umkehr method, and calibrating instrument by standard lamp tests with new hardware and software including step motor, rotary encoder, controller, and visual display. This system takes full advantage of Windows interface and information technology to realize adaptability to the latest Windows PC and flexible data processing system. This automatic system also utilizes card slot of desktop personal computer to control various types of boards in the driving unit for operating Dobson spectrophotometer and testing devices. Thus, by automating most of the manual work both in instrument operation and in data processing, subjective human errors and individual differences are eliminated. It is therefore found that the ozone data quality has been distinctly upgraded after automation of the Dobson instrument.
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김준(Jhoon Kim),조희구(Hi Ku Cho),정연진(Yeon Jin Jung),이윤곤(Yun Gon Lee),이방용(Bang Yong Lee) 한국기상학회 2006 대기 Vol.16 No.2
This study examines seasonal variability of the surface energy balance at the King Sejong Station, Antarctica, using measurements and estimates of the components related to the balance for the period of 1996 to 2004. Annual average of downward shortwave radiation at the surface is 81 Wm?² which is 37% of the extraterrestrial value, with the monthly maximum of 188 Wm?² in December and the minimum of 8 Wm?² in June. These values are relatively smaller than those at other stations in Antarctica, which can be attributed to higher cloudy weather conditions in Antarctic front zone. Surface albedo varies between ∼0.3 in the austral summer season and ∼0.6 in the winter season. As a result, the net shortwave radiation ranges from 117 Wm?² down to 3 Wm?² with annual averages of 43 Wm?². Annual average of the downward longwave radiation shows 278 Wm?², ranging from 263 Wm?² in August to 298 Wm?² in January. The downward longwave radiation is verified to be dependent strongly on the air temperature and specific humidity, accounting for 74% and 79% of the total variance in the longwave radiation, respectively. The net longwave radiation varies between 25 Wm?² and 40 Wm?² with the annual averages of 30 Wm?². Accordingly, the annual average energy balance is dominated by radiative warming of a positive net all-wave radiation from September to next March and radiative cooling of a negative net all-wave radiation from April to August. The net all-wave radiative energy gain and loss at the surface is mostly balanced by turbulent flux of sensible and latent heat. The soil heat flux is of negligible importance in the surface energy balance.
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김준(Jhoon Kim),박상서(Sang Seo Park),조나영(Nayeong Cho),김우경(Woogyung Kim),조희구(Hi Ku Cho) 한국기상학회 2011 대기 Vol.21 No.4
The climatology of surface UV radiation for Seoul, presented in Cho et al. (1998; 2001), has been updated using measurement of surface erythemal ultraviolet (EUV) and total ultraviolet (TUV) irradiance (wavelength 286.5~363.0 ㎚) by a Brewer Spectrophotometer (MK-IV) for the period 2004~2010. The analysis was also carried out together with the broadband total (global) solar irradiance (TR ; 305~2800 nm) and cloud amount to compare with the UV variations, measured by Seoul meteorological station of Korean Meteorological Agency located near the present study site. Under all-sky conditions, the day-to-day variability of EUV exhibits annual mean of 98% in increase and 31% in decrease. It has been also shown that the EUV variability is 17 times as high as the total ozone in positive change, whereas this is 6 times higher in negative change. Thus, the day to day variability is dominantly caused rather by the daily synoptic situations than by the ozone variability. Annual mean value of daily EUV and TUV shows 1.62 kJm?² and 0.63 MJm?² respectively, whereas mean value of TR is 12.4 MJm?² (143.1Wm?²). The yearly maximum in noon-time UV Index (UVI) varies between 9 and 11 depending on time of year. The highest UVI shows 11 on 20 July, 2008 during the period 2004~2010, but for the period 1994~2000, the index of 12 was recorded on 13 July, 1994 (Cho et al., 2001). A 40% of daily maximum UVI belongs to “low (UVI < 2)”, whereas the UVI less than 5% of the maximum show “very high (8 < UVI < 10)”. On average, the maximum UVI exceeded 8 on 9 days per year. The values of Tropospheric Emission Monitoring Internet Service (TEMIS) EUV and UVI under cloud-free conditions are 1.8 times and 1.5 times, respectively, higher than the all-sky measurements by the Brewer. The trend analysis in fractional deviation of monthly UV from the reference value shows a decrease of -0.83% and -0.90% decade?¹ in the EUV and TUV, respectively, whereas the TR trend is near zero (+0.11% decade?¹). The trend is statistically significant except for TR trend (p = 0.279). It is possible that the recent UV decrease is mainly associated with increase in total ozone, but the trend in TR can be attributed to the other parameters such as clouds except the ozone. Certainly, the cloud effects suggest that the reason for the differences between UV and TR trends can be explained. In order to estimate cloud effects, the EUV, TUV and TR irradiances have been also evaluated for clear skies (cloud cover < 25%) and cloudy skies (cloud cover ≥ 75%). Annual mean values show that EUV, TUV and TR are 2.15 kJm?², 0.83 MJm?², and 17.9MJm?² for clear skies, and 1.24 kJm?², 0.46 MJm?², and 7.2 MJm?² for cloudy skies, respectively. As results, the transmission of radiation through clouds under cloudy-sky conditions is observed to be 58%, 55% and 40% for EUV, TUV and TR, respectively. Consequently, it is clear that the cloud effects on EUV and TUV are 18% and 15%, respectively lower than the effects on TR under cloudy-sky conditions. Clouds under all-sky conditions (average of cloud cover is 5 tenths) reduced the EUV and TUV to about 25% of the clear-sky (cloud cover < 25%) values, whereas for TR, this was 31%. As a result, it is noted that the UV radiation is attenuated less than TR by clouds under all weather conditions.
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김준(Jhoon Kim),조희구(Hi-Ku Cho),이윤곤(Yun Gon Lee),오성남(Sung Nam Oh),백선균(Seon-Kyun Baek) 한국기상학회 2005 대기 Vol.15 No.2
Atmospheric ozone changes temporally and spatially according to both anthropogenic and natural causes. It is essential to quantify the natural contributions to total ozone variations for the estimation of trend caused by anthropogenic processes. The aims of this study are to understand the intrinsic natural variability of long-term total ozone changes and to estimate more reliable ozone trend caused by anthropogenic ozone-depleting materials. For doing that, long-term time series for Seoul of monthly total ozone which were measured from both ground-based Dobson Spectrophotometer (Beck #124)(1985-2004) and satellite TOMS (1979-1984) are analyzed for selected period, after dividing the whole period (1979~2004) into two periods; the former period (1979~1991) and the latter period (1992~2004). In this study, ozone trends for the time series are calculated using multiple regression models with explanatory natural oscillations for the Arctic Oscillation(AO), North Atlantic Oscillation(NAO), North Pacific Oscillation(NPO), Pacific Decadal Oscillation(PDO), Quasi Biennial Oscillation(QBO), Southern Oscillation(SO), and Solar Cycle(SC) including tropopause pressure(TROPP). Using the developed models, more reliable anthropogenic ozone trend is estimated than previous studies that considered only QBO and SC as natural oscillations (eg; WMO, 1999). The quasi-anthropogenic ozone trend in Seoul is estimated to -0.12 %/decade during the whole period, -2.39 %/decade during the former period, and +0.10 %/decade during the latter period, respectively. Consequently, the net forcing mechanism of the natural oscillations on the ozone variability might be noticeably different in two time intervals with positive forcing for the former period (1979-1991) and negative forcing for the latter period (1992-2004). These results are also found to be consistent with those analyzed from the data observed at ground stations (Sapporo, Tateno) of Japan. In addition, the recent trend analyses for Seoul show positive change-in-trend estimates of +0.75 %/decade since 1997 relative to negative trend of -1.49 %/decade existing prior to 1997, showing -0.74 %/decade for the recent 8-year period since 1997. Also, additional supporting evidence for a slowdown in ozone depletion in the upper stratosphere has been obtained by Newchurch et al.(2003).
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김민석(Minseok Kim),이서영(Seoyoung Lee),조예슬(Yeseul Cho),구자호(Ja-Ho Koo),염성수(Seong Soo Yum),김준(Jhoon Kim) 한국기상학회 2020 대기 Vol.30 No.4
To understand the characteristics of the relationship between visibility and particulate matter (PM) in different meteorological conditions, we investigated the contributions of PM and relative humidity (RH) to visibility in Seoul, South Korea. For the period from 2001 to 2018, both PM and RH show descending trends, resulting in a visibility increase. PM has little impact on the hourly variation of visibility, which could be explained more by the RH variability. Meanwhile, the daily change of PM accounts for daily visibility variation. For the monthly variation of visibility, both PM and RH showed similar influence. The correlation coefficients of PM<SUB>10</SUB>, PM<SUB>2.5</SUB>, and RH with visibility was -0.486, -0.644, and -0.556, respectively, which became higher during the high PM seasons of spring and winter. The correlation coefficient between PM<SUB>2.5</SUB> and visibility was -0.454 for RH higher than 80%, and -0.780 for RH between 40% and 60%. From 2017 to 2018, there were 10 cases of extreme visibility impairment, among which five cases were incurred by high PM pollution, and two cases were by high humidity. Further analysis with PM chemical composition measurements is required to better understand the characteristics of visibility in Seoul.
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