• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제23권1호
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• pp.34-38
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• 1995

A diagnostic study on the summertime air mass thunderstorms occurring in the middle region of South Korea was made by analyzing the data of surface and upper air observations as well as the surface and upper level weather charts. The key parameters used in the present study are the amount of precipitable water below 850 hPa level, the vertical profiles of water vapor content and wind, and both the temperature difference and the equivalent potential temperature difference between 850 hPa and 700 hPa levels. It is found from this study that the summertime air mass thunderstorms in the middle region of South Korea can be classified into two distinct types, type I and type II. The thunderstorms of type I occur under the atmospheric conditions of high moisture content, low vertical wind shear in low levels, and conditional instability between 850 hPa and 700 hPa levels. On the other hand, the thunderstorms of type II occur under the atmospheric conditions of less moisture content, higher wind shear and conditional instability. Furthermore, our study suggests that atmospheric instability and the amount of water vapor below 850 hPa level are complementary in the development of air mass thunderstorms. The complementary nature between these two parameters may be an explanation for the thunderstorm development in the areas of low atmospheric water vapor content such as the plains of eastern Colorado.

• 전기학회논문지
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• 제63권10호
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• pp.1377-1383
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• 2014

This paper deals with eddy current loss of magnetic coupling with radial permanent magnet (PM) using analytical method such as a space harmonic method. Superposition of two kinds analysis model is used to analyze eddy current loss induced in inner PM and outer PM of magnetic coupling. When the eddy current is induced, the environmental temperature increases, and the permanent magnet(PM) characteristics are degraded because the performance of PM is greatly influenced by temperature rise. Hence, the calculation of eddy current loss becomes an important factor in the magnetic coupling. In order to analyze eddy current loss, first, on the basis of the magnetic vector potential and two-dimensional(2-D) polar-coordinate system, the magnetic field solutions of the radial magnetized PM are obtained. And we obtain the analytical solutions for the eddy current density produced by permanent magnet. Lastly, analytical solutions for eddy current loss are derived by using equivalent, electrical resistance calculated from magnet volume and analytical solution for eddy current density. This analytical results are validated by comparing with the 2-D finite element analysis (FEA).

• 한국건설순환자원학회논문집
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• 제5권1호
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• pp.131-138
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• 2010

본 연구에서는 보통포틀랜드 시멘트(이하 OPC)제조과정의 분쇄공정 중 밀출구에서 배출되는 비교적 가격이 저렴하면서, 수화열면으로도 효과일 것으로 예상되는 입자분포를 갖는 시멘트(이하 CC)를 대상으로 플라이애시(이하 FA)와 고로슬래그 미분말(이하 BS)를 복합치환하는 3성분계 저발열 시멘트로의 개발 가능성을 검토하기 위하여 유동성, 강도, 간이단열온도 상승량 등 기초적인 특성에 대하여 분석하고자 한다. 실험결과로 유동성은 CC의 치환율이 증가함에 따라 저하하는 경향을 보였고, FA+BS의 치환율이 늘어남에 따라 증가하는 경향을 나타냈다. 공기량은 CC의 치환율이 증가함에 따라 미소하게 감소하는 경향을 나타냈고, FA+BS의 치환율이 증가함에 따라 감소하였다. 응결특성으로 CC 및 FA+BS의 치환율이 증가 할수록 응결 시간은 지연되었다. 간이 단열에 의한 온도 상승량은 전반적으로 CC 치환율이 증가할수록, FA+BS의 치환율이 증가할수록 피크온도는 감소하였고, 이후 온도저하가 완만해 지는 경향을 나타냈다. 압축강도는 CC 및 FA+BS 치환율이 증가할수록 저하하였는데, 재령이 경과함에 따라 장기강도는 Plain과 동등하거나 동등 이상의 강도를 발현 하였다. 종합적으로 CC에 FA+BS를 치환하였을 때 유동성 및 공기량은 저하하는 경향을 나타냈으나, 수화열 면에서 양호한 저감효과를 보여 3성분계 저발열 시멘트로의 개발이 가능성할 것으로 사료된다.

• 대기
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• 제34권2호
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• pp.139-151
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• 2024

The Yeongdong region has suffered from severe snowstorms and the relevant damage such as traffic accidents on slippery roads, and the collapse of greenhouses and temporary buildings. While a lot of research on snowfall has been conducted, the detailed study of snow crystals' phase and habit through intensive observations and the relevant microphysical analysis is still lacking. Therefore, a snowflake camera, PARSIVEL, and intensive radiosonde soundings were utilized to investigate phase and habit changes in solid precipitation. Two remarkable episodes of phase and habit changes were selected such as 19 March 2022 and 15 February 2023. Both events occurred in the synoptic condition of the High in the north and the Low passing by the south, which was accompanied by rapid temperature cooling below 2.5 km. During the events of a short period between 3 to 6 hours, the temperature at 850 hPa decreased by about 4 to 6℃. This cooling led to a change in the main habit of snow particles from riming to aggregate, identified with both MASC and PARSIVEL. Meanwhile, the LDAPS model analyses do not successively represent the rapid cooling and short-term variations of solid precipitation, probably by virtue of overestimating low-level equivalent potential temperature during these periods. The underlying causes of these the low-level temperature variations within 6 hours, still remain unclear. It might be associated with mesoscale orographic phenomenon due to the mountains and East Sea effects, which certainly needs an intensive and comprehensive observation campaign.

• Animal Bioscience
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• 제37권5호
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• pp.896-907
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• 2024

Objective: The potential of aqueous extract of Christ's thorn jujube (Ziziphus spina-christi) leaves (SLAE) to reduce the negative impacts of heat stress on production performance and physiological traits was investigated in dual-purpose layers under subtropical farming. Methods: A total of 200, 25-week-old laying hens (Inshas strain) were randomly assigned to four dietary treatments including SLAE at 0, 2.5, 5.0, and 7.5 mL/kg, respectively. The average temperature-humidity index value was 26.69 during the experimental period. The SLAE contained saponin (0.045%), total flavonoid content of 17.9 mg of quercetin equivalent/100 g and overall antioxidant capacity concentration of 17.9 mg of ascorbic acid equivalent/100 g. Results: The maximum final body weight (BW), BW gain, egg weight, number, and mass occurred at the level of SLAE7.5 inclusion. The egg quality was significantly higher in SLAE groups than in control, and overall, SLAE7.5 had the most favorable influence at 28 and 32 weeks. Liver and kidney function, as well as lipids profile, improved significantly by SLAE inclusion; the lowest concentrations of these parameters were in SLAE7.5 hens. Treatment with SLAE7.5 increased total antioxidant capacity and endogenous antioxidant enzymes compared to control, whereas no effect on superoxide dismutase was noticed. Conclusion: The addition of SLAE at 7.5 mL/kg diet improved egg laying performance and quality, metabolic profiles, and antioxidant status during hyperthermia conditions.

• 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 Microbiology and Biotechnology
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• 제31권10호
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• pp.1455-1464
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• 2021

Trehalose is a non-reducing disaccharide in increasing demand for applications in food, nutraceutical, and pharmaceutical industries. Single-step trehalose production by trehalose synthase (TreS) using maltose as a starting material is a promising alternative process for industrial application due to its simplicity and cost advantage. Pseudomonas monteilii TBRC 1196 was identified using the developed screening method as a potent strain for TreS production. The TreS gene from P. monteilii TBRC 1196 was first cloned and expressed in Escherichia coli. Purified recombinant trehalose synthase (PmTreS) had a molecular weight of 76 kDa and showed optimal pH and temperature at 9.0 and 40℃, respectively. The enzyme exhibited >90% residual activity under mesophilic condition under a broad pH range of 7-10 for 6 h. Maximum trehalose yield by PmTreS was 68.1% with low yield of glucose (4%) as a byproduct under optimal conditions, equivalent to productivity of 4.5 g/l/h using enzyme loading of 2 mg/g substrate and high concentration maltose solution (100 g/l) in a lab-scale bioreactor. The enzyme represents a potent biocatalyst for energy-saving trehalose production with potential for inhibiting microbial contamination by alkaline condition.

• 대기
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• 제32권4호
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• pp.307-322
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• 2022

A drone has recently got attention as an instrument for weather observation in lower atmosphere because it can produce the high spatiotemporal resolution weather data even though the weather phenomenon is inaccessible. Sea fog is a weather phenomenon occurred in lower atmosphere, and has observational limitations because it occurs on the sea. Therefore, goal of this study is to analyze the vertical structures about inflow, development and dispersion of sea fog using the high-resolution weather data with the meteorological sensor-equipped drone. This study observed sea fogs in the west coast of the Korean peninsula from March to October 2021 and investigated one sea fog inflowed into the coast on June 8th 2021. θ_e - q_v diagrams (θ_e: equivalent potential temperature, q_v: water vapor ratio) and vertical wind structures were analyzed. At inflow of sea fog, moist adiabatically stable layer was formed in 0-300 m and prevailing wind was switched from south-southwesterly to west-southwesterly under 120 m. Both changes are favorable for sea fog on the location. θ_e and q_v plummeted in a layer 0-183 m. The inflowed sea fog developed from 183 m to 327 m by mixing with ambient atmosphere on top of sea fog. Also, strong mechanical turbulence near ground drove a vertical mixing under stable layer. At dispersion of sea fog, as θ_e on ground gradually increased, air condition was changed to neutral. Evaporation occurred on both bottom and top in sea fog. These results induced dissipation of sea fog.

• 원예과학기술지
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• 제28권3호
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• pp.403-408
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• 2010

본 실험은 비닐온실 내에서 0%, 35%, 55%, 75% 차광처리에 따른 진달래($Rhododendron$ $mucronulatum$ Turcz.)와 영산홍($R.$ $indicum$ (L.) Sweet) 묘목의 생리적 반응을 조사하기 위하여 수행되었다. 차광처리는 생육 후반기인 2008년 9월 9일부터 11월 5일까지 시행되었다. 차광처리는 9월의 낮 온도를 0.9-$1.7^{\circ}C$, 10월에는 0.8-$1.7^{\circ}C$ 정도를 낮추는 효과가 관측되었다. 차광처리 전 진달래 및 영산홍의 함수율은 각각 68.5%, 66.3%이었으며, 차광처리 기간 후 75% 차광 하의 진달래의 함수율은 66.2%로써 3.4%가 감소하였으며, 영산홍은 65.9%로써 0.6%가 감소하였다. 두 수종 모두 차광 수준이 높아질수록 감소율이 낮아지는 유사한 경향을 보였다. 영산홍의 광합성능력은 차광 수준이 높아질수록 높았는데 75% 차광에서 $9.63{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$로 가장 높았다. 한편, 세포간극 내 $CO_2$의 농도, 기공전도도 및 증산율 역시 전광 하의 묘목에 비하여 차광처리에 따라 높았는데 55%, 35% 및 75% 차광순이었다. 수분이용효율은 전광의 묘목이 차광처리 묘목에 비하여 상대적으로 높은 것으로 조사되었다. 차광처리를 받지 않은 진달래 잎색은 자주색에 가까운 색으로 변색한 반면, 차광처리 수준이 높을수록 육안으로도 녹색이 지속되고 있는 것이 관찰되었다. 이러한 차광 수준별 진달래 잎색의 변화를 Munsell Color Chart로 정리한 결과 전광의 경우 R(red)과 Y(yellow) chart의 색이 많은 반면 차광 수준이 높을수록 G(green), Y의 chart에 속하는 비율이 높아 여전히 녹색을 많이 띄고 있었다.

• 한국지구과학회지
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• 제35권1호
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• pp.41-53
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• 2014

겨울철 동해안 강수 현상에 대한 규명을 위하여 라디오존데를 활용한 특별관측을 2012년 1월 5일부터 2월 29일까지 실시하였고, 이 연구는 대기의 불안정을 나타내는 다양한 변수를 활용하여 강수 사례의 분석을 수행하였다. 그 결과, 강수가 발생할 때 지표면(1000 hPa)에서 중층(약 750 hPa)까지의 상당온위가 증가하는 것을 볼 수 있었고, 이러한 대기층(1000~750 hPa)은 불안정을 일으키기에 충분한 수준의 수증기를 함유하고 있었다. 대류가용잠재에너지의 시간적인 변화를 살펴본 결과 강수가 발생하였을 때 증가하는 것을 볼 수 있었고, 연직바람쉬어의 경우에서도 대류가용잠재에너지와 마찬가지로 강수 기간 동안 상승하여 일정수준 이상의 값을 유지하는 것을 확인할 수 있었다. 강수에 따른 대기 구조의 상세한 분석을 위하여 지상 원격 탐사 자료와 지상 관측 자료를 활용하여 분석을 수행하였다. 또한 가강수량과 바람벡터를 이용하여 가강수량플럭스를 계산하였다. 가강수량플럭스와 강수량은 북동풍 계열의 바람이 발생하였을 때 높은 관계성을 보였다. 그 결과 동해안영역에서 발생하는 강수 현상에서는 풍계와 같은 역학적인 작용의 이해가 중요한 것으로 판단되었다.