• 설비공학논문집
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• 제21권12호
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• pp.715-732
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• 2009

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2008. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends in thermal and fluid engineering have been surveyed in the categories of general fluid flow, fluid machinery and piping, new and renewable energy, and fire. Well-developed CFD technologies were widely applied in developing facilities and their systems. New research topics include fire, fuel cell, and solar energy. Research was mainly focused on flow distribution and optimization in the fields of fluid machinery and piping. Topics related to the development of fans and compressors had been popular, but were no longer investigated widely. Research papers on micro heat exchangers using nanofluids and micro pumps were also not presented during this period. There were some studies on thermal reliability and performance in the fields of new and renewable energy. Numerical simulations of smoke ventilation and the spread of fire were the main topics in the field of fire. (2) Research works on heat transfer presented in 2008 have been reviewed in the categories of heat transfer characteristics, industrial heat exchangers, and ground heat exchangers. Research on heat transfer characteristics included thermal transport in cryogenic vessels, dish solar collectors, radiative thermal reflectors, variable conductance heat pipes, and flow condensation and evaporation of refrigerants. In the area of industrial heat exchangers, examined are research on micro-channel plate heat exchangers, liquid cooled cold plates, fin-tube heat exchangers, and frost behavior of heat exchanger fins. Measurements on ground thermal conductivity and on the thermal diffusion characteristics of ground heat exchangers were reported. (3) In the field of refrigeration, many studies were presented on simultaneous heating and cooling heat pump systems. Switching between various operation modes and optimizing the refrigerant charge were considered in this research. Studies of heat pump systems using unutilized energy sources such as sewage water and river water were reported. Evaporative cooling was studied both theoretically and experimentally as a potential alternative to the conventional methods. (4) Research papers on building facilities have been reviewed and divided into studies on heat and cold sources, air conditioning and air cleaning, ventilation, automatic control of heat sources with piping systems, and sound reduction in hydraulic turbine dynamo rooms. In particular, considered were efficient and effective uses of energy resulting in reduced environmental pollution and operating costs. (5) In the field of building environments, many studies focused on health and comfort. Ventilation. system performance was considered to be important in improving indoor air conditions. Due to high oil prices, various tests were planned to examine building energy consumption and to cut life cycle costs.

• 한국구조물진단유지관리공학회 논문집
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• 제21권5호
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• pp.49-55
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• 2017

1970년대에 여러 연구자가 시제품 시험장비를 가지고 인발시험을 실시하였으며, 인발시험은 콘크리트 강도를 결정하는 신뢰할 만한 비파괴검사 방법(NDT)으로 입증되었다. 우리는 고강도 콘크리트 강도를 추정하기 위하여 직경 10 mm볼트에 홈이 파인 파단형 인발 볼트와 인발너트, 그리고 로드셀이 필요 없는 오일 유압펌프를 포함한 간이 인발시험법을 제안하였다. 저비용, 간편성 및 편의성을 갖는 간이인발시험의 이점을 검증하기 위하여, 30 MPa 및 50 MPa 급 두가지 유형의 콘크리트로 제작된 4개의 모의벽체를 대상으로 로드셀을 장착한 간이인발시험을 사용하여 인발시험을 실시하였다. 인발하중과 콘크리트 압축강도는 재령 7일까지는 매일, 그리고 14일, 21일, 28일에 측정되었다. 시험결과 인발하중과 콘크리트 압축강도는 매우 밀접한 상관관계를 보여주었으며 따라서 인발하중이 현장에서 구조물의 고강도 콘크리트 강도를 평가할 수 있다는 것을 확인할 수 있었다. 파단형 인발볼트 직경과 콘크리트 강도와의 관계식으로 y=0.05x+3.79(x=콘크리트 압축강도, y=파단형 인발볼트 직경)이 도출되었으며 결정계수는 0.88로 나타났다.

• 한국환경과학회지
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• 제20권10호
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• pp.1329-1336
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• 2011

The objectives of this study are to examine the processing of oils contamination soil by means of using a micronano-bubble soil washing system, to investigate the various factors such as washing periods, the amount of micro-nano bubbles generated depending on the quantity of acid injection and quantity of air injection, to examine the features involved in the elimination of total petroleum hydrocarbons (TPHs) contained in the soil, and thus to evaluate the possibility of practical application on the field for the economic feasibility. The oils contaminated soil used in this study was collected from the 0~15 cm surface layer of an automobile junkyard located in U City. The collected soil was air-dried for 24 hours, and then the large particles and other substances contained in the soil were eliminated and filtered through sieve No.10 (2 mm) to secure consistency in the samples. The TPH concentration of the contaminated soil was found to be 4,914~5,998 mg/kg. The micronano-bubble soil washing system consists of the reactor, the flow equalization tank, the micronano- bubble generator, the pump and the strainer, and was manufactured with stainless material for withstanding acidic phase. When the injected air flow rate was fixed at 2 L/min, for each hydrogen peroxide concentrations (5, 10, 15%) the removal percents for TPH within the contaminated soil with retention times of 30 minutes were respectively identified as 4,931 mg/kg (18.9%), 4,678 mg/kg (18.9%) and, 4,513 mg/kg (17.7%). And when the injected air flow rate was fixed at 2 L/min, for each hydrogen peroxide concentrations (5, 10, 15%) the removal percents for TPH within the contaminated soil with retention times of 120 minutes were respectively identified as4,256 mg/kg (22.3%), 4,621 mg/kg (19.7%) and 4,268 mg/kg (25.9%).

• 해양환경안전학회지
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• 제26권6호
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• pp.689-697
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• 2020

위험유해물질(HNS, Hazardous and Noxious Substances)은 해상운송 과정에서 다양한 사고에 노출되어 있어 많은 양이 바다에 유출될 우려가 있다. HNS 유출에 따른 해양환경의 손상은 유류 유출에 의한 손상보다도 훨씬 큰 것으로 알려져 있다. 특히 해저로 침강하여 침적되는 HNS는 해저생태계에 돌이키기 어려운 피해를 주게 되므로, 반드시 회수되어야 한다. 해저로부터 HNS를 회수하기 위해서는 해저침적 HNS에 대한 정확한 탐지, 안정화 처리 및 회수를 위한 절차와 장비가 필요하다. 그 중에서도 기계적 회수장치를 개발하기 위해서는 성능지표를 이용하여 성능요건을 선정하고, 이를 토대로 기계적 회수장치에 대한 개념설계가 이루어져야 한다. 따라서 본 연구에서는 해저침적 HNS의 회수 절차에서 요구되는 기계적 회수장치에 대한 개념설계안을 제시하였다. 개념설계안으로 해저침적 HNS를 회수하기 위한 기본 시나리오를 제시하고, 자체적 밀폐 성능을 가지는 흡인 기초를 활용하는 방안을 채택하였다. 기계적 회수장치는 흡인 기초, 오염 방지, 펌프 시스템, 제어 시스템, 모니터링 장비, 위치정보 장비, 이송 장비, 탱크로 구성된다. 이러한 개념설계안은 기계적 회수장치의 부품 및 형상을 결정하는 기본설계에 반영되어 활용될 것으로 기대된다.

• 한국환경과학회지
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• 제11권10호
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• pp.1109-1116
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• 2002

본 연구는 제지류를 소각 처리할 때 발생하는 각종 휘발성 유기화합물에 대한 배출농도를 분석하였다. 실험대상으로는 일상생활에서 다양한 용도로 사용되는 제지류를 A4용지류 (A4 새종이, A4 잉크젯, A4레이져), 신문용지류 (콩기름 신문, 일반 신문), 포장용 Box지, 서류봉투류, 일회용 종이컵류, 화장지류로 분류하였고, 분류된 제지류의 수분함량과 소각시 발생하는 휘발성 유기화합물농도와 소각 재 함량을 분석하였다. 제지류 소각시 발생되는 휘발성 유기화합물을 Furan계, Aldehyde계, Aromatic계, Aliphatic Alkene계, Aliphatic Alkane계, Chlorine계, Ketone계로 분류할 때 가장 많이 발생하는 VOCs로는 Furan계로서 전체 배출농도의 57.4%였고, 그 다음으로 Aromatic계 (22.8%), Aliphatic Alkene계 (14.9%)의 순으로 놀은 평균농도를 나타냈다. 발생되는 휘발성 유기화합물 중 이중 결합을 포함하는 화합물 (Aromatic계, Aliphatic Alkene계, Ketone 및 Aldehyde계)틀의 상대적인 배출비중은 전체 배출농도에 대해 약 40.8%로써, 제지류의 소각에서 발생되는 휘발성 유기화합물의 40% 이상이 대기 중의 오존, 광화적 산화물 및 스모그의 전구체로써 작용할 수도 있을 것이다. 연구 사용된 전체 혼합 제지류 소각시 휘발성 유기화합물중 대표적인 발암성 물질인 Benzene, dichlorornethane, chloroform도 각각 60.5 ug/g, 0.8 ug/g 및 0.1 ug/g 정도 발생될 수 있음을 볼 수 있었다. 따라서, 소형 소각로에서의 제지류의 소각시 상당량의 발암성물질도 배출되므로, 소형 소각로에서도 적절한 VOCs의 제어장치가 꼭 필요한 것으로 판단된다. 본 연구에서 사용된 10가지의 제지류가 가지고 있는 평균 수분함량은 7.2% 정도로써 일반적인 도시폐기물의 제지류 수분함량 (4.5~10%)에 속하는 결과를 보였으며, 평균 9.0 %의 소각잔재 (BottomAsh) 함유량을 보였다. 이러한 결과는 제지류를 소형 소각로에서 소각시 유해 휘발성유기화합물의 발생에도 불구하고, 적절한 대기오염 방지시설을 설치한다면 소각처리가 폐기물 부피감소 측면으로는 상당한 경제적 타당성을 가지고 있음을 암시한다.

• 한국건축시공학회지
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• 제18권1호
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• pp.17-24
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• 2018

비파괴 시험 중 선 매입 인발시험법은 아마도 현장의 콘크리트 압축강도를 평가하기 위해 널리 사용되는 기술이라고 할 수 있다. 인발시험은 콘크리트 타설 전에 특별히 계획된 형태의 철재 봉을 설치하여 콘크리트가 굳은 다음 그 봉을 인발하여 그때의 하중을 측정하여 콘크리트 강도를 평가하는 방법으로 미국과 캐나다에서는 콘크리트 구조물 공사중에 콘크리트 강도를 결정하는 신뢰할 만한 시험법으로 각각 ASTM C 900과 CSA A23.2에 규격화 되어 있다. 직경 12mm볼트에 홈이 파인 파단형 인발 볼트와 인발너트, 그리고 로드셀이 필요 없는 오일유압펌프로 구성된 간이인발시험법을 초고강도 콘크리트 강도를 추정하기 위하여 제안되었다. 인발시험과 간이인발시험의 이점을 검증하기 위하여, 80MPa 및 100MPa 급 두 가지 유형의 콘크리트로 제작된 4개의 시험벽체와 2개의 슬래브를 대상으로 로드셀을 장착한 간이인발시험을 사용하여 인발시험을 실시하였다. 인발하중과 콘크리트 압축강도, 파단형 인발볼트의 파단 여부를 재령 7일까지는 매일, 그리고 14일, 21일, 28일, 90일에 측정하였다. 인발하중과 콘크리트 압축강도의 상관곡선은 매우 높은 신뢰도를 보여주었으며, 따라서 인발시험이 현장에서 구조물의 초고강도 콘크리트 강도를 평가할 수 있다는 것을 확인할 수 있었다. 파단형 인발볼트 직경과 콘크리트 강도와의 관계식으로 y=0.0184+5.4(x=콘크리트 압축강도(MPa), y=파단형 인발볼트 직경(mm))를 제안하였다. 본 연구에서 얻은 결과로 간이인발시험은 유용하며 저비용, 간편성 및 편의성에 대한 가능성이 검증되었다.

• Journal of Biosystems Engineering
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• 제25권3호
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• pp.221-226
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• 2000

Hot air heater with light oil burner is the most common heater for greenhouse heating in the winter season in Korea. However, since the thermal efficiency of the heater is about 80∼85%, considerable unused heat amount in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The heat recovery system is made for plant bed or soil heating in the greenhouse. The system consisted of a heat exchanger made of copper pipes, ${\Phi}12.7{\times}0.7t$ located in the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tank. The total heat exchanger area is 1.5$m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to the performance test it could recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690\ell$/hr from the waste heat discharged. The exhaust gas temperature left the heat exchanger dropped to $100^{\circ}C$ from $270^{\circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{\circ}C$ from $21^{\circ}C$ at the water flow rate of $690\ell$/hr. By the feasibility test conducted in the greenhouse, the system did not encounter any difficulty in operations. And, the system could recover 220,235kJ of exhaust gas heat in a day, which is equivalent of 34% of the fuel consumption by the water boiler for plant bed heating of 0.2ha in the greenhouse.

• 설비공학논문집
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• 제20권6호
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• pp.427-446
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• 2008

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2006 has been accomplished. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro heat exchanger and siphon cooling device using nano-fluid. Traditional CFD and flow visualization methods were still popular and widely used in research and development. Studies about diffusers and compressors were performed in fluid machinery. Characteristics of flow and heat transfer and piping optimization were studied in piping systems. (2) The papers on heat transfer have been categorized into heat transfer characteristics, heat exchangers, heat pipes, and two-phase heat transfer. The topics on heat transfer characteristics in general include thermal transport in a cryo-chamber, a LCD panel, a dryer, and heat generating electronics. Heat exchangers investigated include pin-tube type, plate type, ventilation air-to-air type, and heat transfer enhancing tubes. The research on a reversible loop heat pipe, the influence of NCG charging mass on heat transport capacity, and the chilling start-up characteristics in a heat pipe were reported. In two-phase heat transfer area, the studies on frost growth, ice slurry formation and liquid spray cooling were presented. The studies on the boiling of R-290 and the application of carbon nanotubes to enhance boiling were noticeable in this research area. (3) Many studies on refrigeration and air conditioning systems were presented on the practical issues of the performance and reliability enhancement. The air conditioning system with multi indoor units caught attention in several research works. The issues on the refrigerant charge and the control algorithm were treated. The systems with alternative refrigerants were also studied. Carbon dioxide, hydrocarbons and their mixtures were considered and the heat transfer correlations were proposed. (4) Due to high oil prices, energy consumption have been attentioned in mechanical building systems. Research works have been reviewed in this field by grouping into the research on heat and cold sources, air conditioning and cleaning research, ventilation and fire research including tunnel ventilation, and piping system research. The papers involve the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies on indoor air quality took a great portion in the field of building environments. Various other subjects such as indoor thermal comfort were also investigated through computer simulation, case study, and field experiment. Studies on energy include not only optimization study and economic analysis of building equipments but also usability of renewable energy in geothermal and solar systems.