• 한국자동차공학회논문집
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• 제16권6호
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• pp.176-183
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• 2008

Performance of electrostatic diesel PM filtration systems (E-DPS) with different types has been tested using the carbon particles generated by spark discharge in laboratory. Among the five electrostatic precipitators, the multiple wires cylindrical E-DPS with the highest collection efficiency and relatively lower differential pressure at the flow rate of $1\;m^3$/min, as an applicable device to diesel engine as an after treatment system, has been combined with another collection cylinder to improve the collection efficiency of diesel particulate matters generated from diesel engines. The multiple wires cylindrical E-DPS combined with the cylindrical collector showed the collection efficiency of more than 60% at the engine speed of 2,000 rpm with the engine loads of 25 and 50%.

• 설비공학논문집
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• 제29권1호
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• pp.38-42
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• 2017

This study proposes an idea for energy saving in apartment machine rooms. A conventional district heating system is equipped with constant-flow pumps and bypass valves to regulate pump differential pressure. Each family unit is equipped with a constant-flow on/off valve. This leads to excessive hot water circulation and a high return temperature. To reduce energy loss, this study assumes that each family unit is renovated with a heating valve which regulates the return temperature at $35^{\circ}C$. The hot water supply pump is also replaced with a pump with an inverter to vary flow rate. Expected energy savings is then estimated from field test data. According to the results, pump electricity consumption was reduced by 6,100 kWh for a family unit building over about half a year. The supply temperature can also be lowered by $5^{\circ}C$, which can contribute to a production of electricity of 10.3 kWh/ton of hot water.

• Nuclear Engineering and Technology
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• 제46권1호
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• pp.39-46
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• 2014

A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

• 한국항행학회논문지
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• 제18권5호
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• pp.513-517
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• 2014

본 논문에서는 대기환경의 악화 방지와 개선을 위하여 현재 수동으로 관리되고 있는 집진기 관리시스템을 대신하여 무선을 이용하여 집진기를 관리하는 RF 모니터링 시스템을 설계하고 구현하였다. 제안한 시스템은 산업현장 내 다수의 집진기에 대한 가동시간, 전력량, 차압값 등을 무선으로 모니터링 하여 관리자의 PC에 표시하고 저장할 뿐만 아니라 장애 발생 시 이를 관리자의 휴대폰으로 알려 줌으로서 고부가가치의 집진기 모니터링 시스템의 구현이 가능하다. 따라서 본 논문에서 구현한 RF 모니터링 시스템을 통하여 대기배출원관리시스템(SEMS)에 각 집진기의 정보를 기록함에 있어서 불필요한 손실을 줄일 수 있다.

• 대한약리학회지
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• 제29권2호
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• pp.213-223
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• 1993

급성 신성 고혈압쥐 (2-kidney, 1-ligation type)의 전신성 동맥계와 폐 동맥계에 대한 내피 의존적 혈관반응성을 규명하기 위하여, 적출 혈관 및 마취상태의 흰쥐에 대한 acetylcholine (ACh)의 혈관이완작용 및 혈압강하 작용을 측정하였다. 혈장 renin 활성(PRA)은 신동맥 결찰전 $7.31{\pm}0.63\;ng/ml/hr$ A I에 비해 결찰 $6{\sim}8$일후에는 $19{\sim}22\;ng/ml/hr$ A I으로 유의성있게 증가하였으며, 이는 수축기혈압의 상승과 $(154{\pm}1.83{\rightarrow}190{\sim}215\;mmHg)$ 일정한 상관성을 유지하였다. 신성 고혈압쥐 및 정상 혈압쥐의 흉곽 대동맥은 내피세포 존재시 ACh에 의해 용량의존적으로 이완되었으며, 이때 신성고혈압쥐에서의 반응은 정상 혈압쥐에 비해 유의성있게 감소하였다(각각 34% 및 86%, p<0.01). 또한 ACh은 신성 고혈압쥐 및 정상 혈압쥐의 폐동맥에 대해서도 내피세포 존재시에 이완반응을 초래하였다. 그러나, 흉곽 대동맥에서와는 달리 두 군간에 유의성있는 차이가 없었다. 이들 반응은 내피세포 제거후 또는 EDRF 억제제 (L-NAME, MB, $10^{-5}$ M) 투여후 유의성있게 억제되었다. $ACh(0.1{\sim}10\;{\mu}g/kg,\;i.v.)$은 신성 고혈압쥐 및 정상 혈압쥐에서 전신성 동맥압의 강하를 초래하였는데, 신성 고혈압쥐에서 다소 감소하였으나 유의성있는 차이는 없었으며 ($SAPm;\;10\;{\mu}g/kg$에서 각각 39%, 46 %), 이들 작용은 L-NAME(30 mg/kg, i.v.) 전처치후 유의성있게 억제되었다. ACh에 의한 폐동맥압 강하는 신성 고혈압쥐 및 정상 혈압쥐 사이에 서로 비슷하게 나타났다. 그러나, 신성 고혈압 쥐 및 정상 혈압쥐에서 ACh에 의한 폐동맥압의 강하율은 전신성 동맥압의 강하율보다 유의성있게(p<0.01) 작았으며, 또한 L-NAME $(0.1{\sim}100\;mg/kg,\;i.v.)$에 의한 폐동맥압의 상승은 전신성 동맥압의 상승보다 유의성있게(p<0.01) 작았다. 이상의 실험 결과들은 급성 신성 고혈압쥐의 전신성 동맥계에서는 내피세포 손상이 초래되지만, 폐동맥계에서는 초래되지 않는다는것을 제시해준다. 또 신성고혈압쥐 및 정상 혈압쥐에서 EDRF 의 basal release 및 ACh 유발성 EDRF function은 전신성 동맥계에 비해 폐동맥계에서 적다는 것을 제시해준다.

• Computers and Concrete
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• 제21권6호
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• pp.717-726
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• 2018

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use of nano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that $SiO_2$ nanoparticles can improve the mechanical behavior of concrete. Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton's principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load. The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method. The effects of different parameters such as $SiO_2$ nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluid pressure and earthquake intensity are discussed on the seismic response of the structure. From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of $SiO_2$ nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.

• Computers and Concrete
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• 제24권2호
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• pp.125-135
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• 2019

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use of nano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that SiO2 nanoparticles can improve the mechanical behavior of concrete. Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton's principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load. The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method. The effects of different parameters such as SiO2 nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluid pressure and earthquake intensity are discussed on the seismic response of the structure. From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of SiO2 nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.

• 대한기계학회논문집B
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• 제31권2호
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• pp.188-194
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• 2007

New diesel engines equipped with common-rail injection systems and advanced engine management control allow drastic decreases in the production of particulate matters and nitrogen oxides with a significant advantage in terms of the fuel consumption and $CO_2$ emissions. Nevertheless, the contribution of exhaust gas after treatment in the ultra low emission vehicles conception has become unavoidable today. Recently the passive type DPF(Diesel Particulate Filter Trap) system for diesel passenger vehicle has been manufactured into mass production from a French automotive maker since the year of 2000. This passive DPF system fully relies on the catalytic effects from additives blended into the diesel fuel and additives injected into the DPF system. In this study, the effects of PM regeneration in the commercial diesel passenger vehicle with the passive type DPF system were investigated in chassis dynamometer CVS(constant volume sampler)-75 mode. As shown in this experimental results, the DPF regeneration was observed at temperature as low as $350^{\circ}C$. And the engine-controlled the DPF regeneration founded to be one of the most promising regeneration technologies. Moreover, the durability of this DPF system was evaluated with a season weather in terms of the differential pressure and exhaust gas temperature traces from a road test during the total mileage of 80,000km.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.179-185
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• 2014

Average temperature and temperature uniformity in a battery cell are the important criteria of the thermal management of the battery pack for hybrid electric vehicles and electric vehicles (HEVs and EVs) because high power with large size cell is used for the battery pack. Thus, liquid cooling system is generally applied for the HEV/EV battery pack. The liquid cooling system is made of multiple cooling plates with coolant flow paths. The cooling plates are inserted between the battery cells to reject the heat from batteries to coolant. In this study, the cooling plate with U-shaped coolant flow paths is considered to evaluate the effects of coolant flow condition on the cooling performance of the system. The counter flow and parallel flow set up is compared and the effect of flow rate is evaluated using CFD tool (FLUENT). The number of counter-flows and flow rate are changed and the effect on the cooling performance including average temperature, differential temperature, and standard deviation of temperature are investigated. The results show that the parallel flow has better cooling performance compared with counter flow and it is also found that the coolant flow rate should be chosen with the consideration of trade-off between the cooling performance and pressure drop.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1540-1555
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• 2021

The plate-type fuel assembly adopted in nuclear research reactor suffers from complicated effect induced by non-uniform irradiation, which might affect its stress conditions, mechanical behavior and thermal-hydraulic performance. A reliable numerical method is of great importance to reveal the complex evolution of mechanical deformation, flow redistribution and temperature field for the plate-type fuel assembly under non-uniform irradiation. This paper is the first part of a two-part study developing the numerical methodology for the thermal-fluid-structure coupling behaviors of plate-type fuel assembly under irradiation. In this paper, the thermal-fluid-structure coupling methodology has been developed for plate-type fuel assembly under non-uniform irradiation condition by exchanging thermal-hydraulic and mechanical deformation parameters between Finite Element Model (FEM) software and Computational Fluid Dynamic (CFD) software with Mesh-based parallel Code Coupling Interface (MpCCI), which has been validated with experimental results. Based on the established methodology, the effects of non-uniform irradiation and fluid were discussed, which demonstrated that the maximum mechanical deformation with irradiation was dozens of times larger than that without irradiation and the hydraulic load on fuel plates due to differential pressure played a dominant role in the mechanical deformation.