• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.362-365
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• 2007

In this paper we present development process and results of some cases for underground pad transformer and switchgear. Some characteristic factors was considered and tested to improve the functions of the case, such as natural convection of cooling air between the internal and external cases, properties of material that used as external panel etc. Proposed designs and functional characteristics will be adapted to making the cases of underground facilities after the elaborated tests. The results obtained from this study will improve the scenery of a street.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.123-128
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• 1997

In-situ bearing metal temperature and shaft vibration are measured for an unload type and a preload type, m=0.87, of vertical guide bearing for hydraulic pump-turbines. Guide bearing is a tiltingpad type journal bearing consisting of eight pads whose diameter is 1,450 mm. Rotational speed is 450 rpm. Both the bearing metal temperature and the shaft vibration are very high in the unload type but are slight in the preload type, comparatively. The bearing metal temperature is decreased due to the increase of cooling effect by the increase of preload and the shaft vibration is decreased due to the increase of bearing stiffness. It is concluded that the preload effect of a guide bearing for hydraulic pump-turbines has a large influence on the bearing metal temperature and the shaft vibration.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.57-61
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• 1999

The effect of the microstructure of gray cast iron on friction properties was investigated by using a pad-on-disk type friction tester. Cast iron samples used in this investigation were obtained from "step block" castings, which were designed to produce microstructure with different graphite flake morphologies from different cooling rate and solidification rate. Results of this work showed that the gray cast iron disks with long graphite flakes showed less fading. The rotors containing smaller amounts of ferrite showed higher friction coefficient and better fade resistance than others.an others.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.375-378
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• 2010

Hot and high speed plume exhausted during KSLV-I flight test is cooled down by an amount of water ejected from 'gas deflector cooling system' of launch complex to reduce the effects on the launch vehicle and launch complex. In this study, simplified axisymmetric computational calculation with 2-phase is carried out to analysis the water injection effects on flow field.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.137-142
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• 2003

In automotive brake systems, the frictional heat generated can cause high temperature at the interface of rotor and pad which may deteriorate the material properties of the sliding parts and can result in brake fade. Conventionally, a pie-shaped 3-dimentional model is adopted to calculate temperature of ventilated disk using finite element method. To overcome the difficulties in preparing 3D finite element model and reduce the computational time required, the ventilated rotor is to be analyzed, in this study, as an axisymmetric finite element model in which, taking into considerations the effects of cooling passages, a homogenization technique is used to obtain the equivalent thermal properties and boundary conditions for the elements placed at the vent holes. Numerical tests show the proposed procedure can be successfully applied in practice, replacing 3-dimensional thermal analysis of ventilated disk.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.164-168
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• 1999

온실은 동절기 난방을 주목적으로 설비되어 년중 작물재배 시는 하절기 온실내부 온도가 필요이상으로 상승하여 실내온도가 35-4$0^{\circ}C$ 정도로 올라가는데 이러한 상태에서의 온도는 많은 작물의 생육적온을 벗어난 온도로서 고온장해를 나타낸다. 이 같은 문제점을 해결하기 위해 몇 가지 냉방방법이 알려져 있는데 에어컨 등과 같은 냉방장치를 이용한 기계적 냉각방식과 수분증발을 통한 증발식 냉각방식으로 대별되며 이중 기계적인 냉방방식은 설비나 유지관리 면에서 비용이 많이 들어 비경제적이고, 증발냉각 방식중에서도 Fan and Pad 법이 가장 효과가 좋은 것으로 알려져 있으나 이역시 설치 및 유지비가 많이 들고, vep의 탈부착이 어려워 고정시켜놓을 경우 동계 광투과에 방해가 되는 등의 문제가 많다. (중략)

• Journal of Animal Environmental Science
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• v.19 no.1
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• pp.33-38
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• 2013

We conducted investigations of the information and welfare of broiler chickens in Korea. The livestock housing of all broiler chicken farms were windowless type, bell feeder and nipple waterer were used, and stocking density was relatively higher (ranging from 18.2 $birds/m^2$ to 24.2 $birds/m^2$) than RSPCA's welfare standards for chicken hens (less than 19 $birds/m^2$). The ratios of sandwich panel, urethane form, slate, and steel plate in roofing materials were 61%, 21%, 13%, and 5%, respectively. The ratios of sandwich panel, urethane form, brick, and steel plate in wall materials were 61%, 21%, 13%, and 5%, respectively. The ratios of soil and concrete in flooring materials were 10% and 90%. The mist spray, fan, and cooling pad in cooling facilities were 42%, 32%, and 26%, respectively. Thus we believe that present data contribute to develop the animal welfare certification for broiler chickens and to improve animal welfare in Korea.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.223-229
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• 2002

패드엔팬을 이용하여 물 공급량, 팬 회전속도의 변화에 따른 온실 냉방효과 시험한 결과를 요약하면 다음과 같다. 가. 패드에 흐르는 물 공급량별로 일중 11:00-16:00경에 물 공급량이 분당 60$\ell$이상 공급하면 8.0~9.5$^{\circ}C$의 온도차를 낼 수 있으며, 팬을 1170rpm으로 회전시킬 경우 6.0~9.$0^{\circ}C$의 온도차를 낼 수 있었다. 나. 온실과 팬출구 공기의 온도차는 일중 14:30~16:00 경에 60$\ell$이상의 물을 패드에 공급하는 경우 6.0~7.8$^{\circ}C$ 온도 강하 효과가 있고 팬을 1170rpm으로 회전시킬 경우에는 외기온 28$^{\circ}C$일 때 3$0^{\circ}C$이하로 온도를 강하시킬 수 있었다. 다. 패드에 흘리는 물의량을 60 $\ell$/min 이상을 공급하여 주면 30분당 20~28$\ell$의 물을 증발시킬 수 있다. 배출팬 회전속도가 1170rpm일 경우에 30분당 20~30$\ell$의 물을 증발시키는 것으로 나타났다. 라. 본시험에 사용된 패드엔팬의 흡.배기의 엔탈피변화는 8:30이전에는 흡기가 배기보다 온도가 낮아 엔탈피가 양(+)의 값을 나타났고, 8:30 이후에는 흡기가 배기 보다 온도가 높아 -2.0~-4.OkJ/kg의 엔탈피 차만큼 냉각효과가 있었으며, 냉방효율을 65~80% 수준으로 나타났다. 마. 본시험결과로 패드엔팬의 냉기 공급방식만 개선된다면 이동식인 박스형 패드엔팬도 냉방장치로 사용 가능할 것으로 판단된다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.79-79
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• 2017

국내 여름철의 고온다습한 기후환경으로 인하여 온실 내부의 냉방 및 제습이 필수적인데, 온실 냉방 방식 중 증발냉각 시스템이 가장 효율이 높다고 알려져 있다. 하지만 증발냉각 시스템은 건조한 기후 지역에서 발달한 방식으로, 작물의 증산작용으로 인한 온실 내부 습도 상승에 따른 문제점이 발생되어 다습한 여름철 국내 기후에는 반드시 냉각과 제습이 동시에 필요하다. 따라서 증발냉각 방식 중 Fan and Pad 방식과 리튬브로마이드 수용액을 이용한 온실 냉방 및 제습을 위한 복합시스템에 관한 연구가 진행중이다. 현재 리튬브로마이드 수용액 제습 시 발생되는 발열량과 수용액의 무게변화와 같은 수용액의 흡습성질 대한 정확한 지표가 나타나 있지 않다. 이에 연구를 진행하기에 앞서 리튬브로마이드 흡습성질에 관한 데이터 자료가 필요하다고 판단되어 기초실험을 진행하였고, 본 연구에서는 Pilot Scale의 재생 순환시스템을 통해 리튬브로마이드 수용액의 흡습성질을 이용한 재사용 방안을 제시하였고, 시스템 내에서 외부투입공기와 작동유체의 흡습성질에 의한 반응 전후 온도변화 예측 모델을 수립하였다. 따라서 본 연구를 통해 리튬브로마이드 수용액의 흡습성질을 분석하고, 이를 이 용한 재생 순환 시스템에 관한 연구를 진행할 예정이다.

• Nutrition Research and Practice
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• v.6 no.1
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• pp.16-20
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• 2012

The effects of retrograded rice on body weight gain, gut functions, and hypolipidemic actions in rats were examined. When the retrograded rice was produced by repetitive heating and cooling cycles, it contained significantly higher amounts of resistant starch ($13.9{\pm}0.98%$) than is found in common rice ($9.1{\pm}1.02%$) (P < 0.05). Sprague-Dawley rats were fed either common rice powder or retrograded rice powder, and mean body weight gain was significantly lower in the retrograded rice group (P < 0.05). The liver weight of the retrograded rice group ($14.5{\pm}0.5\;g$) was significantly lower than that of the common rice group ($17.1{\pm}0.3\;g$, P < 0.05). However, the weights of other organs, such as the kidney, spleen, thymus, and epididymal fat pad were not significantly affected by rice feeding. Intestinal transit time tended to be lower in rats fed retrograded rice when compared to rats fed the common rice, but the difference was not significant. The retrograded rice diet significantly increased stool output when compared to that in the common rice powder diet (P < 0.05), whereas fecal moisture content (%) was significantly higher in the retrograded rice group ($23.3{\pm}1.2$) than that in the common rice group ($19.1{\pm}1.2$) (P < 0.05). The retrograded rice group had significantly lower plasma cholesterol (P < 0.05), liver cholesterol (P < 0.05), and triacylglycerol contents in adipose tissue (P < 0.05) when compared to those in the common rice group. In conclusion, retrograded rice had higher resistant starch levels compared with those of common rice powder, and it lowered body weight gain and improved lipid profiles and gut function in rats.