• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1466-1473
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• 2012

Soft icecream is made by scraping an ice formed on the inside of the cylindrical evaporator, where R-404A is evaporating in the annulus. The heat transfer characteristics of the refrigerant evaporation and those during icecream formation were experimentally investigated. Results show that the refrigerant-side heat transfer coefficients are highly dependent on the location in the evaporator due to the complex annulus configuration. The heat transfer coefficient at the inlet is generally lower than those of other locations. The average heat transfer coefficient increases as heat flux increases or saturation temperature decreases. A correlation is developed to predict the refrigerant-side heat transfer coefficient. The icecream-side heat transfer coefficient oscillates continuously due to the periodic removal of ice formed on the surface. The average heat transfer coefficient during icecream formation is approximately 280 W/$m^2K$, and that during single-phase cooling increased from 150 W/$m^2K$ to 250 W/$m^2K$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.1
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• pp.12-16
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• 2004

In this study, we have investigated the development of the crystal growth stability and reproducibility for large and high-quality DAST. DAST crystal were grown from a saturated methanol solution by a slow cooling method and DAST was synthesized by the condensation of 4-methyl-n-methyl pyridinum tosylate, which was prepared from 4-pocoline and methyl toluenesulponate and 4-N-dimethyl amino-bezaldehyde in the presence of piperidine. We had synthesized DAST crystals in dry Argon atmosphere in order to avoid the formation of hydride organge co-crystals, DAST$.$$H_2O$. Since DAST molecules crystallize in a humid atmosphere, crystal structure become centrosymmetric, and then second order NLO (nonlinear optical) properties would be disappeared. We fixed the growth orientation of DAST crystal (001) surface. The crystal growth was proceeded at a cooling rate of $H_2O$/day and the cooling period is for 4 days. The dimensions of seed crystal was $2.5\times 3.6\times0.4\textrm{mm}^3$ and we have obtained a DAST crystal with the dimension of $10\times 10.5\times3.0\textrm{mm}^3$. The color of grown DAST crystal is red and it's surface appears to be metallic green.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.58-68
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• 2009

Three-dimensional distributions of longwave radiation flux for the April-September 1998 period are generated from radiative transfer calculations using the GEWEX Asian Monsoon Experiment (GAME) reanalysis temperature and humidity profiles and International Satellite Cloud Climatology Project (ISCCP) cloudiness as inputs to understand the effect of cloud radiative forcing in the monsoon season. By subtracting the heating of the clear atmosphere from the cloudy radiative heating, cloud-induced atmospheric radiative heating has been obtained. Emphasis is placed on the impact of horizontal gradients of the cloud-generated radiative heating on the Asian monsoon. Cloud-induced heating exhibits its maximum heating areas within the Indian Ocean and minimum heating over the Tibetan Plateau, which establishes the north-south oriented differential heating gradient. Considering that the differential heating is a ultimate source generating the atmospheric circulation, the cloud-induced heating gradient established between the Indian Ocean and the Plateau can enhance the strength of the north-south Hadley-type monsoon circulation. Cooling at cloud top and warming at cloud bottom, which are the vertical distributions of cloud-induced heating, can exert on the monsoon circulation by altering the atmospheric stability.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.253-253
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• 2009

전세계적 고유가 및 $CO_2$ 배출로 인한 지구 온난화 문제 동 앞으로의 에너지 개발은 지속가능하며, 환경친화적이어야 한다. 따라서 가장 값싼 에너지원의 하나이며, 또한 환경문제에서도 유리한 원자력 에너지에 대한 세계적인 관심이 지난 약 30년 정도의 침체기간을 거친후 미국, 중국, 인도, 유럽, 아시아 등을 중심으로 다시 부활하고 있다. 그러나 미래 원자력에너지의 활발한 이용 및 지속 가능성을 위해서는 고준위 방사성 폐기물의 처리문제가 반드시 해결되어야 하며, 그 중에서도 사용후핵연료의 관리문제는 원자력 발전소의 계속 운전을 위해 시급히 해결되어야 한다. 한국원자력연구원도 2008년 12월 결정된 정부의 "미래 원자력시스템 개발 Action Plan" 을 통해 이러한 사용후핵연료의 관리문제를 해결하기 위한 연구 과제를 10여년 동안 수행해오고 있으며, 그 중 하나가 파이로(Pyroprocess) 공정개발이다. 1997년부터 관련연구가 착수되어, 2001년부터는 약 6년간에 걸쳐 파이로의 전처리 공정 및 전해환원 공정에 대한 실험실 규모 실증시설인 ACPF(Advanced spent fuel Conditioning Process Facility)를 개발한 바 있다. 또한 향후 파이로 기술의 상용화를 위해 2016년 까지 약 10톤/년 규모의 공학규모 파이로 실증시설(ESPF)을 건설하고 이를 기초로 2025년까지 100톤/년 규모의 파이로 상용시설 (KAPF) 을 건설하여 여기서 나온 우라늄 및 TRU 물질을 이용해 2030년까지 개발 예정인 소듐냉각 고속로에 필요한 핵연료를 제작, 공급하는 계획을 가지고 있다. 이 논문에서는 파이로 시설개발의 가장 중요한 인자중 하나인 시설의 안전성 확보를 위해 외국 및 국내에서의 연구개발 현황을 알아보고 안전성 분석 및 평가방법에 대한 기본 인자들을 도출해 보았다. 또한 파이로 시설의 인허가를 위한 사용후핵연료 처리시설 규제관련 국, 내외의 연구현황도 알아보았다.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.546-554
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• 1995

Vacuum cooling of crisphead lettuce by pilot-scale vacuum cooling apparatus, transportation under the conventional and cold-chain systems and distribution were carried out for its freshness prolongation and application of cold-chain system for fresh fruits and vegetables. Changes in temperatures of crisphead lettuce were also measured during transportation. $Q_{10}$ value for respiration rate of crisphead lettuce was $1.7{\sim}2.4$ and its initial freezing point was $-0.2^{\circ}C$. Cooling the vegetable to $0^{\circ}C$ was possible in less than 30 minutes by vacuum cooling. The shelf-life was extended by more than 90% by the combination of vacuum cooling and low temperature distribution.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.532-536
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• 1995

Effect of water activity $(0.32{\sim}0.89)$ on the physicochemical properties of sweet potato starch during the storage for 5, 15 and 30 days at $40^{\circ}C$ was investigated. Shapes and sizes of starch granules were not changed. X-ray diffraction patterns of the starches appeared equally Ca-crystal structure. Sorption isotherm with storage day was sigmoidal. A slight loss of iodine affinity, increase in water binding capacity, and decrease in swelling power at $80^{\circ}C$ occurred as water activities increased. Viscosity pattern under Brabender Amylogram was not significantly changed with water activity, but initial pasting temperature decreased as water activity increased. The viscosity at $50^{\circ}C$, consistency and setback were increased with increasing storage day and water activity.

• The Korean Journal of Ecology
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• v.28 no.2
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• pp.85-92
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• 2005

This study emphasizes syntaxonomy and syndynamics of intermediate (Zwischen) moor (area: 14,000 $m^2$) at Mt. Shinbul in Yangsan, southeastern Korean Peninsula. A total of 105 vascular plant species including 26 monitor-species were recorded. Analysis by the $Z\"{u}rich$-Montpellier School's method distinguished eight vegetation units: Eleocharitis-Blyxetum echinospermae ass. nov., Eriocaulon sikokianum-Utricularia racemosa community, Eleocharis wichurai-Molinia japonica community, Platanthero-Molinietum japonicas, Miscanthus sinensis for. purpurascens community, Tripterygium regelii community, Symplocos chinensis-Quercus mongolica community, Symplocos chinensis-Quercus dentata community. PCoA (Principal Coordinates Analysis) shows that vegetation changes and distributional aspects are associated with both moisture condition and sunlight on the ground layer and soil nutrient level (mesotrophic to oligotrophic). Most important to Molinietea japonicas being representative intermediate moor vegetation at the southeasternmost fringe of the Korean Peninsula is the local cooling effect by mountainous cloud and mist zone resulting in shorter and wetter growing season. The Yangsan moor vegetation was compared with earlier descriptions of related Mujechi moor from anthropogenic and natural moor vegetations.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.74-77
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• 2000

사출성형에 관한 연구는 오랜 역사를 가지고 있으며 공정 시뮬레이션을 위한 상용화된 CAE 프로그램을 포함하여 많은 연구가 진행되는 분야중의 하나이다. 그러나 다양한 고분자 재료의 성질, 금형의 복잡한 형상 및 성형조컨 둥의 변화로 인해 금형설계 및 제작 그리고 사출성형시 상당한 어려움을 겪게 된다. 사출성형 공정에서는 금형온도, 플라스틱 재료, 냉각수, 보압과 사출압 등의 여러 가지 공정변수가 있어 현장전문가의 경험에 의해 사출금형의 제작이 이루어지는 경우가 보통이다 이와 같은 경험에 의한 금형 제작은 상당한 납기지연과 노동집약적인 방식으로 흘러가게 된다. 금형 제작시 가장 고려해야 될 사항 중의 하나는 사출성형품의 수축이다. 사출성형에서 광음수지는 냉각, 고화하면서 수축하는데 성형품 치수를 유지하기 위해서는 수축하는만큼 금형의 치수를 보정하여야 한다. 이 수축률은 사용수지의 종류와 성형품 크기, 살두께 등에 따라 다르다. 또 동일한 수지일 경우에도 성형조건에 따라 변화하고 특히 배향성을 가진 수지는 유동방향에 따라서도 변화가 있다. 즉, 금형의 온도가 높으면 수축률은 증가하고 사출압력이 높으면 감소한다. 또한 살두께가 두껍고 길이가 길 때 수축률은 증가한다 방향성이 있는 수지는 유동방향에 대하여 지각방향에서 가장 적다. 특히 방향성이 현저한 HDP에서는 유동방향에 따라 수축차가 크므로 성형할 때 변형을 일으키는 경우가 많다. 일반적으로 PE, PP. PA와 같은 결정성 수지는 PS, SAM, ABS 등의 비결정성 수지보다 수축률이 크다. 본 연구에서는 한조산업사에서 제작한 '클랠프 척' 금형 제작과정에서 성형품의 수축으로 인한 금형의 치수보정에 있어서의 문제점을 유동해석 전용 CAE 프로그램인 C-mold를 사용하여 해석하고 평가하였다. 그리하여 현장 전문가가 경험적으로 여러 번의 시행착오를 거쳐 완성된 금형을 제작하던 기존의 방법보다 체계적이고 합리적이며 또한 신속하게 문제를 해결함으로써 궁극적으로 금형설계 및 제작기간을 단축하고자 한다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.73-78
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• 2009

The decay heat of Cs and Sr contained in a LiCl waste salt, generated from an electrolytic reduction process in pyroprocessing of spent nuclear fuel, has been calculated. The calculation has been carried out under some assumptions that most of the LiCl waste is purified and recycled to main process, and the residual is fabricated to make a waste form. As a result, the decay heat from daughter nuclides such as Ba and Y seems to be maximum 4.6 times higher than that from their parent nuclides such as Cs and Sr. The thermal release from Cs and Sr in the LiCl waste is the maximum around the first one month, so an cooling system operation for some time at the beginning would be suggested to control a rapid increase in the temperature of the LiCl waste salt.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.121-131
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• 2003

We have found that the east coast of Korea has had few sea fogs on January, February, November and December for the past 20 years by the analysis of monthly fog frequency and duration time. These phenomena appear to relate to the topographical characteristics of which the Taebaek Mountains descends toward the east to bar the radiation fog. On the other hand, the cause of occurring the spring and summer fog which has 90% of the whole frequency is divided into three cases. The first is the steam fog caused by the advection of the northeast cold air current on the East Sea due to the extension of Okhotsk High. The second is the advection fog caused by cooling and saturation of warm airmass advected on cold sea surface. And the last is the frontal fog caused by the supply of enough vapor due to the movement of low-pressure system and the advection of cold air behind a cold front. While, we simulate the sea fog for the period of the case studies by implementing fog prediction system(DUT-METRI) that makes it possible to forecast the fog in the vertical section of neighborhood of the East Sea and to predict the sea surface wind, relative humidity, ceiling height, visibility etc. Finally we verified this result by satellite image.