• Title/Summary/Keyword: 기류

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A Study on the Determination of the Seasonal Heat Transfer Coefficient in KURT Under Forced Convection (강제대류시 계절에 따른 KURT 내 열전달계수 결정에 관한 연구)

  • Yoon, Chan-Hoon;Kwon, Sang-Ki;Hwang, In-Phil;Kim, Jin
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.8 no.3
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    • pp.189-199
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    • 2010
  • In a high-level waste (HLW) repository, heat is generated by the radioactive decay of the waste. This can affect the safety of the repository because the surrounding environment can be changed by the heat transfer through the rock. Thus, it is important to determine the heat transfer coefficient of the atmosphere in the underground repository. In this study, the heat transfer coefficient was estimated by measuring the indoor environmental factors in the Korea Atomic Energy Research Institute Underground Research Tunnel (KURT) under forced convection. For the experiment, a heater of 5 kw capacity, 2 meters long, was inserted through the tunnel wall in the heating section of KURT in order to heat up the inside of the rock to $90^{\circ}C$, and fresh air was provided by an air supply fan connected to the outside of the tunnel. The results showed that the average air velocity in the heating section after the provision of the air from outside of the tunnel was 0.81 m/s with the Reynolds number of 310,000~340,000. The seasonal heat transfer coefficient in the heating section under forced convection was $7.68\;W/m^2{\cdot}K$ in the summer and $7.24\;W/m^2{\cdot}K$ in the winter.

Development of Tunnel-Environment Monitoring System and Its Installation III -Measurement in Solan Tunnel- (터널 환경 측정 시스템 개발 및 측정 III -솔안터널 측정결과 분석-)

  • Park, Won-Hee;Cho, Youngmin;Kwon, Tae-Soon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.637-644
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    • 2016
  • This paper is a follow-up to previous papers entitled, "Development of Tunnel-Environment Monitoring System and Its Installation" I [1] and II [2]. The target tunnel of these studies is the Solan Tunnel, which is a loop-type, single-track, 16.7-km-long tunnel located in mountainous terrain and passing through the Baekdudaegan mountain range. It is an ordinary railway tunnel designed for both freight and passenger trains. We analyzed the environmental conditions of the tunnel using temperature and humidity data recorded over approximately one year. The data were recorded using the Tunnel Rough Environment Measuring System (TREMS), which measures environmental data in subway and high-speed train tunnels and is installed in three locations inside the tunnel. Previous studies analyzed environmental conditions inside tunnels located in or near a city, whereas the tunnel in this study is located in a mountainous area. The tunnel conditions were compared with those measured outside the tunnel for each month. Hourly changes during summer and winter periods were also analyzed, and the environmental conditions at different locations inside the tunnel were compared. The results are widely applicable in studies on the thermal environment and air quality of tunnels, as well as for computer analysis of tunnel airflow such as tunnel ventilation and fire simulations.

The Distribution of Snowfall by Siberian High in the Honam Region - Emphasized on the Westward Region of the Noryung mountain ranges - (시베리아 고기압 확장시 호남 지방의 강설 분포 - 노령 산맥 서사면 지역을 중심으로 -)

  • 이승호;천재호
    • Journal of the Korean Geographical Society
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    • v.38 no.2
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    • pp.173-183
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    • 2003
  • This study aims to understand the patterns of spatial distribution of snowfall by Siberian High in the Honam region in Korea. In the Honam region, Siberian High induces snowfall dominantly. There is a huge amount of snowfall in the westward of the Noryung mountain ranges to the Wert coast in the Honam region affected by northwesterly wind directly from the Siberian High. The westward of the Noryung mountain ranges such as a heavy snowfall region has a various pattern of distribution of snowfall due to topography. The coast region has a large amount of snowfall by sea effect. And, snowfall amount is decreased from the coast to the inland plain. However, in front of mountain, snowfall is increase by reason of a forced ascending air to the mountain. In general the region where frequently appear a cumuliform cloud has a large amount of snowfall. A cumuliform cloud is frequent in the mountainous region in inland, the coast, and the inland plain in order Snowfall is intense in the coast and the mountainous region, and weak in the inland plain. In the mountainous region, a cumuliform cloud induced tv a forced ascending air by reason of topography generates snowfall mostly. This fact is the main difference with snowfall in the mountainous region and the coast region. In the result, in the Honam region, snowfall distribution and snowfall pattern are various, according to geographical climate factor such as sea and topography. The heavy snowfall region in the Honam region is divided into the coast region affected by sea effect and the mountainous region affected by topography effect.

The Distributions of Liquid Water Content(LWC) and the Potential Enhancement of Precipitation over Andong Area observed from Microwave Radiometer (Microwave radiometer를 이용한 안동지역의 수액량 및 증우가능량 추정)

  • 정관영;김효경;이선기;정영선
    • Korean Journal of Remote Sensing
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    • v.14 no.2
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    • pp.165-174
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    • 1998
  • The observation of liquid water content(LWC) and the estimation of precipitation enhancement by cloud seeding were made over the Andong in Korea from March 1997 through Feb 1998. A dual-channel microwave radiometer was used to measure the liquid water content and water vapor. It was shown that the 90% of observational period had the amount of less than 0.1 mm in LWC, and that the amount of precipitation was proportionally increased to liquid water content. The amount of LWC has maximum in summer and minimum in winter. The content of liquid cloud water was showed higher value from the time of 12 to the time of 17 except for summer season in which it extremely fluctuated with a large precipitation. The majority of liquid water content over the area occurred with westerly and southwesterly wind which were flowed from the Sobaek mountain. The ratio of horizontal LWC flux and vertical precipitation flux, $P_{en}$ is almost ranked in the interval of 0.0~0.5 with maximum of 0.5 in spring, 0.2 in summer and fall, and 0.1 in winter. Accordingly, it is estimated that the potential enhancement of precipitation over Andong area by cloud seeding has high value in spring with westerly wind.

Johnson's Naturalistic Ethics and the Size of Morality (존슨의 자연주의 윤리학과 도덕의 크기)

  • Noh, Yang-jin
    • Journal of Korean Philosophical Society
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    • v.137
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    • pp.131-149
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    • 2016
  • The main purpose of this paper is to inquire into Johnson's defence of naturalistic ethics, and show how it could escape the intractable conundrum that has bothered moral philosophy ever since the early 20th century. Johnson shares the deconstructivist stance in claiming that moral theories are largely metaphorical constructs, and thus their claim to absoluteness is ungrounded. However, Johnson breaks with deconstructivist philosophers by offering a need for a constructive inquiry into "moral understanding." Then, Johnson's recent discussions are more concerned with moral fundamentalism in which he argues, is not only cognitively incorrect but immoral. It is incorrect in that it relies on the false assumptions on human cognition, and is immoral in that it shuts off any moral discussions. Instead, Johnson sees moral experience as a matter of moral deliberation in which we attempt "dramatic rehearsals" in Dewey's terms. Johnson's constructive offer in moral philosophy reminds us of "the size of moral theory," which fits human moral understanding as an embodied being, and this presents a third constructive way over the dichotomous conundrum of moral philosophy between traditional absolutism and nihilistic deconstructivism.

A Study on Flow Distribution in a Clean Room with Multiple Exits (다수의 출구를 가지는 크린룸 내부의 기류분포에 관한 연구)

  • Lee, Jae-Heon;Lee, Sie-Un;Kim, Sukhyun
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.17 no.4
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    • pp.418-425
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    • 1988
  • Since conventional computer program is workable only with velocity boundary condition, in practical fluid passage such as clean room which usually have wide inlets and outlets, it is not easy to measure velocity itself because of its vector property. Furthermore a certain assumption of velocity at boundaries may lead to physically unreasonable results. From this motivation, we have developed a computer program to predict whole flow field imposed on pressure-based boundary condition which can be measured by relatively simple method. The only additional velocity boundary condition that should be imposed on to make the problem unique, are no slip condition at all walls and zero cross stream velocity at inlet. The result of present study was compared with that by Bernoulli equation being used practically. They were coincident well each other within 5%, therefore the validity of the present method is proved. In the present work, the flow field in a clean room subject to pressure-based boundary conditions at an inlet and two exits was predicted numerically. The pressure difference between the inlet and the left exit which keeps relatively low pressure among two exits is fixed as 150[Pa] and the pressure at the right exit is varied from zero to 150[Pa] by the increment of 25[Pa]. For each cases the flow characteristics in the clean room, the velocity profile at the inlet, and the flow rate through the two exits was predicted. The flow rate through the right exit imposed on relatively higher pressure than the left exit decreased linearly according to the increase of pressure of the right exit. When the pressure of the right exit is increased enough to cause back flow at the exit, the flow rate is rapidly decreased.

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Soil Microarthropod Community in the Process of Needle Leaf Decomposition in Korean Pine(Pinus koraiensis) Forest of Namsan and Kwangreung (남산과 광릉수목원의 잣나무림에서 낙엽분해과정에 관련된 토양미소절지동물군집)

  • Bae, Yoon-Hwan;Lee, Joon-Ho
    • The Korean Journal of Soil Zoology
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    • v.4 no.2
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    • pp.75-80
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    • 1999
  • Two years-study with litter bag (mesh size : 0.4 mm, 1.7 m) was carried out from Nov., 1996 to Sept., 1998 to investigate the soil microarthropod community in the process of needle leaf secomposition of Korean pine (Pinus koraiensis) forest in Namsan and Kwangreung, where were supposed to be under different environmental selective pressures. Soil arthropoda collected from litter bags were sorted into suborders or higher taxa. Acari and Collembola were dominant groups, which were 61-68% and 27-35% of total soil arthropod in their numbers, respectively. Among Acari, Oribatida was major group, and Gamasida and Actinedida were minor groups. Abundance of Acari was a little higher in Kwangreng than in Namsan. But there was not significant difference between the arthropod community structure of Namsan and Kwangreng forest. And the different mesh sizes (0.4 mm and 1.7 mm) of litter bags could not make significantly different community structures in the litter bags. One taxon showed different pattern of population dynalics from another. But Oribatida, Gamasida and Collembola showed peak density in July, 1997. All taxa showed lower population densities in cold season i.e. Nov., Jan. and March. There was not significant difference in decomposition rate between Namsan and Kwangreng forest, and between mesh sizes of litter bags. % residual mass of needle leaf was about 40% at 22 months after litter fall.

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A Numerical Study on Smoke Behavior of Fishing Vessel Engine Room (어선 기관실의 연기 거동에 관한 수치해석 연구)

  • JANG, Ho-Sung;JI, Sang-Won
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.5
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    • pp.683-690
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    • 2021
  • The ventilation system of the engine room of a ship is generally installed to supply the combustion air necessary for the internal combustion engine and to remove the heat source generated in the engine room, and it must satisfy the international standard (ISO 8861) for the design conditions and calculation standards for the ventilation of the ship engine room. The response delay of the ventilation system including the fire detector is affected by the airflow formed inside the area and the location of the fire detector. In this study, to improve the initial fire detection response speed of a fire detector installed on a fishing vessel and to maintain the sensitivity of the installed detector, the smoke behavior was simulated using the air flow field inside the engine room, the amount of combustion air in the internal combustion engine, and the internal pressure of the engine room as variables. Analysis of the simulation results showed that reducing the flow rate in the air flow field and increasing the vortex by reducing the internal pressure of the engine room and installing a smoke curtain would accelerate the rise of the ceiling of the smoke component and improve the smoke detector response speed and ventilation system.

Effects of Air Velocity on the Thermal Insulation of Winter-padded Clothing Ensembles at 10℃ Air Temperature -Comparison of Human Wear Trials with a Thermal Manikin- (10℃ 환경에서 기류가 겨울철 패딩 의류의 한 벌 보온력에 미치는 영향 -인체 착용 및 서멀마네킹 측정 비교-)

  • Baek, Yoon Jeong;Cho, Kayoung;Hong, Yujin;Lee, Joo-Young
    • Journal of the Korean Society of Clothing and Textiles
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    • v.45 no.4
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    • pp.703-713
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    • 2021
  • This study was to investigate the thermal insulation of clothing ensembles, including padded jackets with two different filling types. Thermal insulation of the ensemble was measured using a thermal manikin in four conditions (10℃, 30% RH and 20℃, 50% RH with an air velocity of less than 0.15 m·s-1 and 1.5 m·s-1). Ten males participated at 10℃ and 30% RH with an air velocity of less than 0.15 m·s-1 and 1.5 m·s-1. The results showed that the polyester ensemble was warmer than a goose down ensemble in 0.15 m·s-1 conditions and the goose down ensemble had greater thermal insulation than the polyester ensemble at an air velocity of 1.5 m·s-1. Thermal insulation was reduced 5-7% when temperature decreased 10℃ and reduced 40-50% when air velocity reached 1.5 m·s-1 for both ensembles. Thermal insulation of the ensemble in human trials decreased more than a thermal manikin at 10℃, 30% RH with an air velocity of 1.5 m·s-1. Lower temperatures and human trials were effective in identifying the properties of the thermal insulation by filling types even though there were restrictions on the general application because of two types of a clothing ensemble.

Two Different Perspectives of Contemporary Japanese Writers Tracing the Memories of Colonial Taiwan - Tsushima Yuko's Too Savage and Yoshida Shuichi's Road (식민지 타이완의 기억을 그리는 현대 일본 작가들의 서로 다른 두 가지 시선 - 쓰시마 유코 『너무나 야만스러운(あまりに野蛮な)』과 요시다 슈이치 『루(路)』)

  • Jo, Young-Joon
    • Cross-Cultural Studies
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    • v.41
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    • pp.57-84
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    • 2015
  • During the Japanese rule, there was an abundance of Japanese writers using colonial Taiwan as the backdrop for their work. However, after Japan's surrender and Taiwan's independence, such writers became nearly invisible. With recent relations between Taiwan and Japan drawing closer, novels and films tracing the modern relationship of the two nations are continually being introduced. Tsushima Yuko's 2008 novel Too Savage and Yoshida Shuichi's 2009 work Road also sprout from the shift in the two countries' and East Asia's historic and political atmosphere. The two books are similar in the sense that they both use countries as the backdrop and recall colonial times. However, the perspectives of the two greatly differ. This paper will compare the meaning behind the narrative strategies that the two authors take in remembering colonial Taiwan and the relationship of the two countries. It will be quite meaningful for Koreans to research the recent works of Japanese writers depicting Taiwan, as Korea also shares a similar modern history. It will also be a good opportunity to ruminate on the entangled modern history of the East Asian region and review relevant literature and culture.