• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.10a
• /
• pp.134-135
• /
• 2009

선박에서 주로 채택되는 열교환기는 쉘튜브형과 판형열교환기로 분류된다. 이 연구에서는 소형쉘튜브형 열교환기의 설계에서 중요한 요소인 냉각튜브와 벽면과의 간격에 따른 유동특성을 입자영상유속계를 이용하여 계측하였다. 연구 결과 벽면과의 거리변화에 따른 임계간격비는 0.25전후로 추정되었으며 벽면효과에 따른 정량적 데이터를 확보하였다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.3
• /
• pp.291-303
• /
• 2016

Recently, various forms of diverging sections in tunnels have been designed as the demand for underground passageway in urban areas increases. Therefore, the complexity of the ventilation system in tunnels with diverging sections requires a ventilation analysis method different from the conventional method for the straight tunnels. None of the domestic and foreign tunnel ventilation design standards specifies the method for the ventilation network analysis, and the numerical analysis methods have been most widely used. This paper aims at reviewing the ventilation network analytical method applicable as the design standard. The proposed method is based on the characteristic equations rather than the numerical analysis. Thanks to the advantages of easy application, the Hardy-Cross method has been widely applied in the fields of mine ventilation and tunnel ventilation. However, limitations with the cutting errors in the Taylor series expansion and the convergence problem mainly caused by the mesh selection algorithm have been reported. Therefore, this paper examines the applicability of the ventilation analysis method for network-type tunnels with the gradient method that can analyze flow rate and pressure simultaneously without the configuration of mesh. A simple ventilation analysis method for network-type tunnels is proposed.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.5
• /
• pp.515-522
• /
• 2010

The objective of this study is to investigate the air-side heat transfer characteristics of a spirally-coiled circular fin-tube heat exchanger for various geometric parameters under non-frosting conditions. The heat transfer characteristics of the heat exchanger were analyzed with respect to heat exchanger geometries, and then, the characteristics were compared with those of rectangular-plate fin-tube heat exchangers with discrete fins. The heat transfer coefficient increased with a decrease in the number of tube rows and an increase in the fin pitch. The optimum length of the L-foot was 2.7 mm. In addition, the heat transfer rate increased with a decrease in the tube pitch and the tube thickness. The heat transfer coefficient of the spirally-coiled circular fin-tube heat exchanger was 24.3% higher than that of the rectangular-plate fin-tube heat exchanger.

• Resources Recycling
• /
• v.15 no.3 s.71
• /
• pp.30-37
• /
• 2006

For keeping the indoor air quality, we develop the pulsating heat pipe(PHP) type heat recovery ventilator using an used radiator for vehicles. We compare the PHP type with existing model. There are some merits that are able to change the unit number according to heat load and show us the similar performance to existing models.

• Journal of Life Science
• /
• v.17 no.1 s.81
• /
• pp.82-90
• /
• 2007

In an attempt to establish the appropriate ventilation device for the bottle culture of king oyster mushroom (Pleurotus eryngii), we investigated carbon dioxide concentration and fruiting body formation according to the various ventilation systems within the mushroom house. In addition to, the efficiency of air circulation and growth rate as well as the appearance of physiologically abnormal phenotypes during their growth stage were also evaluated. four different ventilation devices, parallel-pressure type, positive-pressure type, negative-pressure type, and positive- and negative-pressure type were applied in this study. The positive-and negative-pressure type showed the highest efficiency of air circulation as $CO_2$ concentration was 800 ppm and the level of air current was relatively low compared to the other types (the $CO_2$ concentration of parallel-pressure type was 1,400 ppm). Moreover, the stipe length, the cap diameter, yield, and general quality grown in positive- and negative type ventilation device were also better than in the other three devices though it took slightly longer period for harvesting (18.4 days) than the others (17.6, 17.9 and 18.3 days). The appearance of physiologically abnormal phenotypes such as fruiting body lump, soft rot, and brown rot were significantly decreased in positive-and negative type compared to other types, while the appearance rates were not much different for other symptoms of bacterial ooze, stipe limb and stipe bumpy. In summary, we propose that the optimal ventilation system for the bottle culture of king oyster mushroom is positive- and negative type, and this device is expected to increase the total quality as well as yield all year around.

• Journal of Energy Engineering
• /
• v.10 no.3
• /
• pp.214-222
• /
• 2001

The purpose of this research it to develop gas-air rotary heat exchanger using heat pipe and the performances were examined by way of the theoretical analysis and the experiment. Centrifugal force to return the working fluid in heat pipe elements with different radius was evaluated as a function of the revolution speed and inclination angle, and a rotary heat exchanger with 60 heat pipes in 3 rows was designed and manufactured. The inclination angle of a heat pipe relative to the revolving axis was designed to be 2$^{\circ}$and water was used as a working fluid. Experimental result showed the heat exchange rate was enhanced by 16% with compared to the calculated value.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.269-273
• /
• 2011

In present paper focused on the influence of the inlet-outlet area ratio of counter flow manifold on the flow distribution and pressure drop characteristics of a tubular heat exchanger. The characteristics of flow distribution and pressure loss can be obtained depending on the inlet-outlet area ratio. In this paper, a tubular heat exchanger can be designed with minimum flow mal-distribution and better characteristic of pressure loss by choosing the optimum inlet-outlet area ratio.

• Journal of agriculture & life science
• /
• v.50 no.2
• /
• pp.187-194
• /
• 2016

The purpose of this study was to analyze temperature distribution characteristics using a model swine housing for temperature sensor adjustable positioning and developed a sensor and controller embedded exhaust fans utilizing ICT fusion technology for windowless swine housing. Temperature measured by the sensor attached on the exhaust fan was also determined that there is no problem, the temperature is located in the upper fan given the measured errors shown in the 1℃ temperature difference between the lower temperature than the other positions in the model swine housing. The performance of the exhaust fan at maximum output was found to be 1920rpm, air flow rate 125㎥/min. When the open area ratio of 70% one proper air volume of the exhaust fan was found to be 75㎥/min, 60pa. Maximum efficiency in all of the output of the exhaust fan is exhibited at about 70% open area ratio of the damper. The number of revolution of the exhaust fan was 1920rpm when the output was a maximum of 100%. AC output phase of the pulse duty ratio change of the controller was shown to change without delay. It was determined that the instant fan speed control is possible.

• 한국도로학회지:도로
• /
• v.10 no.2
• /
• pp.58-67
• /
• 2008

교통량이 많은 도심지내 장대 지하차도 건설은 교통정체 해소에 기여를 하지만 초기 공사비가 많이 소요되는 단점이 있다. 또한, 화재등 유고시 이용자의 안전을 최우선으로 고려되어야 한다. 즉, 장대 지하차도 건설에 있어서 경제성과 안전성이 함께 만족할 수 있는 건설 방안이 필요하다. 세종지하차도는 이러한 문제점을 극복하고자 다음과 같이 지하차도의 환기방식 및 단면, 포장형식, 사고 예방 및 발생시를 대비한 종합방재시스템을 구축하였다. $\cdot$환기방식은 종류식 환기방식의 경제성과 횡류식 환기방식의 제연성능을 겸비할 수 있는 조합형 환기방식과 Duct Arch 단면을 적용하여 공사비 절감 및 운영시 유지관리비를 획기적으로 절감하였다. $\cdot$지하차도 포장형식은 화재시 내화성이 우수하며 유독가스 발생이 없는 HPC(고성능 콘크리트 포장) 포장을 적용하여 이용자의 안전을 최우선으로 고려하였고 일반 아스팔트 포장 및 배수성 아스팔트 포장에 비해 우수한 성능과 공용수명을 가진 공법을 적용함으로서 유지보수비용의 절감을 가능하게 하였다. 또한, 콘크리트포장의 단점인 소음발생을 최소화하기 위해 타이닝과 그루빙을 적용하였다. $\cdot$지하차도내 화재 등 유고시 신속한 대피가 가능하도록 피난 연락문 간격을 167m 간격으로 설치하고 비상탈출계단 6개소를 확보하였다. 또한 노약자 및 환자의 지하차도 외부로 대피를 돕기 위해 비상엘리베이터 3개소를 설치하는 등 사고발생 시 종합적으로 대처할 수 있는 시스템을 마련하여 적용하였다.

• KOREAN POULTRY JOURNAL
• /
• v.36 no.6 s.416
• /
• pp.96-99
• /
• 2004

사계절이 뚜렷한 국내에서는 여름철 혹서기 사양관리를 하는 방법에 따라 산란율이나 폐사계의 발생빈도가 확연히 차이가 날 수 있다. 이러한 까닭에 기존계사에 비해 단열 및 환기문제에 있어서 보다 효과적인 무창계사라는 현대식 계사가 최근 강조되고 있는 것이다. 그러나 현재 전체 계사의 과반수 이상이 단열이 엉성하고, 완전 자연환기에 의존하는 계사는 물론 적절한 지붕단열, 일부 기계식 환기를 도입한 절충형 계사에서 사육되고 있으므로 이번 여름을 맞이하여 나름대로 대책을 세울 필요가 있다. 특히 지구 온난화 등의 환경적 요인 등을 고려할 때 해가 거듭될수록 여름은 과거 못지않은 수준일 것이라 예상되기 때문이다.