• 한국전자통신학회논문지
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• 제19권1호
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• pp.209-216
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• 2024

육상 새우 양식장은 연안 양식에 비해 생장 환경을 보다 안정적으로 제어할 수 있어 고품질의 대규모 생산에 유리하다. 최적의 새우 생장 환경을 유지하기 위해서는 물의 순환, 적정 수온 유지, 산소 공급, 사료 공급 등 다양한 요소들을 관리해야 한다. 특히, 적절한 수질 관리가 되지 못하면 새우 폐사로 이어지기 때문에 양식장에 24시간 사람이 상주하여 지속적으로 관리해야 하는 어려움이 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 최소한의 인력으로 운영 가능한 육상 양식장 통합 모니터링 시스템을 제안한다. 제안된 시스템은 IoT 기술을 활용하여 육상 양식장의 실시간 영상, 펌프 상태, 수질 데이터, 에너지 사용 현황을 수집하여 서버로 전송한다. 관리자는 웹 인터페이스 및 스마트폰 앱을 통해 서버에 저장된 양식장의 상황을 언제 어디서나 실시간으로 확인하고 필요한 조치를 취할 수 있다. 따라서 관리자가 양식장에 상주할 필요 없이 현장 작업 시간을 크게 줄일 수 있다.

• 한국산업보건학회지
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• 제29권2호
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• pp.176-184
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• 2019

Objective: This study aims to characterize airborne radon and thoron levels ($Bq/m^3$) generated from working environments in three subway stations in Seoul. Method: A radon and thoron detector (EQF3220) was used to monitor real-time airborne radon and thoron levels ($Bq/m^3$) and their daughters ($Bq/m^3$) every two hours. They were monitored not only in the driver's cabin of seven circulation lines, but also three offices, platforms, and water pump reservoirs in the three stations. Results: The average levels of radon and thoron were $67.9Bq/m^3$ (range; $7.2-619.4Bq/m^3$) and $44.4Bq/m^3$ (range; $4.3-819.2Bq/m^3$), respectively. Notably, higher than legal airborne radon levels ($600Bq/m^3$) were frequently monitored in the driver's cabin of seven circulation lines. Airborne radon levels monitored in the platforms and administrative offices were found to be over $100Bq/m^3$. The average equilibrium factors (F) were 0.12 and 0.06, respectively. The percentages detected were found to be 84.9 for radon and 72.4 for thoron, respectively. Conclusions: Significant airborne radon and thoron levels were frequently found to be generated in subway facilities including water reservoirs, platforms and driver's cabins. Further study is necessary to thoroughly investigate airborne radon and thoron in all subway stations and to devise proper measures.

• 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.

• 한국환경과학회지
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• 제21권5호
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• pp.597-603
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• 2012

Non-thermal plasma processing using a dielectric barrier discharge (DBD) has been investigated as an alternative method for the degradation of non-biodegradable organic compounds in wastewater. The active species such as OH radical, produced by the electrical discharge may play an important role in degrading organic compound in water. The degradation of N, N-Dimethyl-4-nitrosoaniline (RNO) was investigated as an indicator of the generation of OH radical. The DBD plasma reactor of this study consisted of a plasma reactor, recycling pump, power supply and reservoir. The effect of diameter of external reactor (15 ~ 40 mm), width of ground electrode (2.5 ~ 30 cm), shape (pipe, spring) and material (copper, stainless steel and titanium) of ground electrode, water circulation rate (3.1 ~ 54.8 cm/s), air flow rate (0.5 ~ 3.0 L/min) and ratio of packing material (0 ~ 100 %) were evaluated. The experimental results showed that shape and materials of ground were not influenced the RNO degradation. Optimum diameter of external reactor, water circulation rate and air flow rate for RNO degradation were 30 mm, 25.4 cm/s and 4 L/min, respectively. Ground electrode length to get the maximum RNO degradation was 30 cm, which was same as reactor length. Filling up of glass beads decreased the RNO degradation. Among the experimented parameters, air flow rate was most important parameters which are influenced the decomposition of RNO.

• Agricultural and Biosystems Engineering
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• 제6권1호
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• pp.22-26
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• 2005

A wind-heat generation system was developed and the system consisted of an electric motor, a heat generation drum, a heat exchanger, two circulation pumps and a water storage tank. The heat generation drum is an essential element determining performance of the system. Frictional heat was generated by rotation of a rotor in the drum filled with a working fluid, and the heat stored in the fluid was used to increase water temperature through the heat exchanger. Effects of some factors such as rotor shape, kind and amount of working fluid, rotor rpm and water flow rate in the heat exchanger, affecting the system performance were investigated. Amounts of heat generated were varied, ranging from 126,000 to 32,760 kJ/hr, depending on combination of the factors. Statistical analysis using GLM procedure revealed that the most influential factor to decide the system performance was amount of the fluid in the drum. Experiments showed that the faster the speed of the rotor, the greater heat was obtained. The greatest efficiency of the heat generation system, electric power consumption rate vs gained heat amount of water, was about 70%. Though the heat amount was not enough for plant bed heating of a 0.1-ha greenhouse, the system would be promising if some supplementary heat source such as air- water heat pump is added.

• 대한의용생체공학회:의공학회지
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• 제26권5호
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• pp.337-341
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• 2005

Blood pulsation has been reported to have an advantageous effect on extracorporeal blood circulation. However, the study of pulsatile blood flow in renal replacement therapy is very limited. The in-vitro experimental results of pulsatile blood flow on ultrafiltration, when compared with the conventional roller pump, are described in this paper. Methods: Blood flow rate (QB) and transmembrane pressure (TMP) were considered as regulating factors that have an influence on ultrafiltration. Experiments were performed under the condition of equal TMP and OB in both pulsatile and roller pump groups, Several kinds of hollow fiber dialyzers were tested using distilled water containing chemicals as a blood substitute. Mean TMP (mTMP) varied from 10 to 90mmHg while the QB was 200ml/min. Results: Ultrafiltration rate (QUF) was found to be linearly proportional to TMP, whereas QB had little influence on QUF. In addition, QUF was higher in the pulsatile group than the roller pump group at the identical TMP. Conclusion: In the controlled test, QUF increased solely as a consequence of blood pulsation, which implies that the pulse frequency represents an additional and important clinical variable during renal replacement therapy.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.122.2-122.2
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• 2010

Knowledge of ground thermal properties is most important for the proper design of BHE(borehole heat exchanger) systems. The configure type, pipe size and thermal performance of the BHE is highly dependent on the ground source heatpump system-efficiency and instruction cost. Thermal response tests with mobile measurement devices were developed primarily for in-situ determination of design data for Standing Column Well apply. The main purpose has been to determine in-situ values of effective ground thermal conductivity and thermal resistance, including the effect of ground-water flow and natural convection in the boreholes. The test rig is set up on a some trailer, and contains a sub-circulation pump, a boiler, temperature sensors, flow meter and a data logger for recording the temperature and circulation fluid flow data. A constant heating power is injected into the SCW through the test rig and the resulting temperature change in the SCW is recorded. The recorded temperature data are analysed with a line-source model, which gives the effective in-situ values of rock thermal conductivity and thermal resistance of SCW.

• 생물환경조절학회지
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• 제28권4호
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• pp.420-428
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• 2019

본 연구에서는 고설 딸기 관부(크라운부) 난방시스템을 전기 온수 보일러, 축열조, 순환 펌프, 관부난방 배관(백색 연질 PE관, 관경 16mm) 및 온도 제어반으로 구성하였다. 관부(크라운부) 난방의 경우 난방 배관을 딸기 관부에 최대한 밀착될 수 있도록 설치하고 배관 위치를 원예용 고정핀으로 고정하였다. 또한 관부 난방시스템의 에너지 효율을 증진하기 위해 축열조 온수 온도를 $20{\sim}23^{\circ}C$, 관부 온도를 $13{\sim}15^{\circ}C$로 관리하였다. 관부난방은 전기 온수보일러를 이용하여 $20{\sim}23^{\circ}C$의 온수를 축열조에 저장하고 순환펌프를 제어하기 위한 온도 센서를 딸기의 관부에 최대한 근접하여 설치하고 온도를 감지함으로써 관부(크라운부)를 집중적으로 난방하는 방식이다. 시험 온실의 난방 처리는 공간 난방 $4^{\circ}C$ + 관부난방(처리 1), 공간 난방 $8^{\circ}C$ (대조구), 공간 난방 $6^{\circ}C$ + 관부난방(처리 2)로 처리하였다. 각 난방처리는 온실 1동에 딸기를 980주를 심었으며, 재배방법은 표준재배법에 준해서 재배하였다. 난방 에너지 소비에 대한 비교시험은 2017년 11월 8일부터 2018년 3월 30일까지 수행되었다. 소비된 누적 전력량은 등유 사용량으로 환산하였고, 등유 소비량은 공간난방 $8^{\circ}C$(대조구)의 경우 1,320L(100%), 공간난방 $4^{\circ}C$ + 관부난방의 경우 928L(70.3%), 공간난방 $6^{\circ}C$ + 관부난방의 경우 1,161L (88%)로 계측되었다. 공간난방 $4^{\circ}C$ + 관부난방(처리 1) 및 공간난방 $6^{\circ}C$ + 관부난방(처리 2)은 $8^{\circ}C$ 공간난방(대조구)에 비해 생육 저하, 수확시기의 지연 등이 없이 비슷하게 딸기 수확이 가능하였으며, 29.7% 및 12%의 난방 에너지가 절감되는 것으로 분석되었다.

• 설비공학논문집
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• 제17권1호
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• pp.16-24
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• 2005

The goal of the present paper is to show the optimum design and operation conditions on 6 kW solar water heating system by using computer simulation with verified modelling. As the object functions, we took not only the amount of acquired and auxiliary heat but LCC, which has a relative importance and decisive role in economy. As expected, the maximum heat is acquired at the slope of collector with the equal degree to the latitude, facing the south. The capacity increase of the circulation pump and the storage tank lead to the increase of acquired heat and the decrease of auxiliary heat, but do not necessarily give economical advantages owing to additional electrical power consumption. In the present system, the minimum LCC can be obtained at the storage tank volume of 450 L and the mass flow rate of 0.344 kg/s.

• 수산해양기술연구
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• 제60권2호
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• pp.194-206
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• 2024

This study focuses on analyzing the energy-saving effects of the recirculation aquaculture system using seawater source heat pumps and solar power generation. Based on the thermal load analysis conducted using the transient system simulation tool, the annual energy consumption of the recirculation aquaculture system was analyzed and the energy-saving effects of utilizing the photovoltaic system was evaluated. When analyzing the heat load, the sea areas where the fish farms are located, the type of breeding tank, and the circulation rate of breeding water were taken into consideration. In addition, a method for determining the appropriate capacity for each operation time was examined when applying the energy storage system instead of the existing diesel generator as an emergency power, which is required to maintain the water temperature of breeding water during power outage. The results suggest that, among the four seas considered, Jeju should be estimated to achieve the highest energy-saving performance using the solar power generation, with approximately 45% energy savings.