• 한국화재소방학회논문지
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• 제29권6호
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• pp.45-50
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• 2015

인화점은 액체 용액의 폭발과 화재의 위험성을 특징짓는 가장 중요한 성질 중 하나이다. 본 연구에서는 두개의 가연성 이성분계 혼합물인 n-decane + n-octanol계 및 acetic acid + n-butanol계의 인화점을 Tag 개방식 장치를 활용하여 측정하였다. 인화점은 그룹기여모델인 UNIFAC 식과, 최적화기법에 의해 계산되었다. 그리고 측정값과 비교하였다. 두 방법 모두 측정값을 잘 모사하였다.

• 소성∙가공
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• 제16권4호
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• pp.282-287
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• 2007

Hot embossing, one of Nanoimprint Lithography(NIL) techniques, has been getting attention as an alternative candidate of next generation patterning technologies by the advantages of simplicity and low cost compared to conventional photolithographies. A typical hot embossing usually, however, takes more than ten minutes for one cycle of the process because of a long thermal cycling. Over the last few years a number of studies have been made to reduce the cycle time for hot embossing or similar patterning processes. The target of this research is to develop an induction heating apparatus for heating a metallic micro patterning mold at very high speed with the large-area uniformity of temperature distribution. It was found that a 0.5 mm-thick nickel mold can be heated from $25^{\circ}C\;to\;150^{\circ}C$ within 1.5 seconds with the temperature variation of ${\pm}5^{\circ}C$ in 4-inch diameter area, using the induction heating apparatus.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.284-288
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• 2015

Training power tiller operators in safe farming is necessary to avoid farming accidents. With the continuing progress in computational technology, driving simulators have become increasingly popular for conducting such training. Purpose: The objective of this study is to develop mock control devices and data acquisition apparatus for a tiller simulator. Methods: Except for the stand and tail wheel adjusting levers, the mock control devices were developed using a tiller handle assay. The data acquisition apparatus was realized using an embedded data-logging device and LabVIEW, the system design software. Results: The control devices of a real handle assay were successfully mimicked by the mock operator control devices, which used sensors for the relevant measurements. The data from the mock devices were acquired and transmitted to the main computer at intervals of 10 ms via Wi-Fi. Conclusions: The developed mock control devices operate similar to real power tillers and can be utilized in power tiller training simulators.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.236-241
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• 2017

Electrohydraulic forming is a high-speed forming process that deforms a blank using electric discharge in liquid. When high voltage is discharged in the water, a shock wave is propagated from the tip of the electrodes to the blank, causing the blank to be deformed into the die. Electrohydraulic forming has many advantages including improved formability and reduced bouncing effect and springback. The objective of this paper was to conduct a feasibility study to identify the electrohydraulic effect. An electrohydraulic forming apparatus was developed and experiments were carried out. The results of the experiment showed that the developed apparatus had sufficient energy to deform the blank into the die. Using the hole to emit residual air in the die was more effective than using the vacuum pump in terms of saving on experiment time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.221-224
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• 2001

In connection with the monitoring of insulation degradation of large power apparatus in order to predict their unexpected service failures, a statistical treatment, such as phase resolved partial discharge analysis(PRPDA), has been established for the on-line monitoring system during the past decades. However, this method has shown some inconveniences to distinguish the nature of the PD source in power apparatus. In this regard, a novel approach based on the chaotic analysis(CAPD) is proposed describing the fundamental ideas, outcomes and different view points from conventional PRPDA. In order to make a model for the possible defects causing sudden failures in service, several types of specimen were prepared. And partial discharge signals, originated from those samples, were measured and analysed by means of PRPDA and CAPD respectively. Throughout this paper, it seems that the correlation between the consecutive PD pulses depending on the nature of PD could be investigated by CAPD. Therefore, it could be considered that the nature of PD source can be distinguished more distinctively when the PRPDA is combined with CAPD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1317-1319
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• 1997

This paper is to study and develope a measurement apparatus for ferroelectricity. The apparatus consists of wave generation part, high voltage amplifier part, measurement part, data acquisition part and the related controll circuits. Single or double excitation wave is digitalized and sent to the external RAM of wave generation part by personal computer. These datas saved in the RAM are converted to analog excitation wave through D/A converter. The frequency of excitation wave is depend on the read-out speed of the RAM by clock pulse. Such generated wave is applied to high voltage amplifier as a input voltage. The output of high voltage amplifier is applied to ferroelectrics and the response is obtained from the charge amplifier of measurement part. The response is sampled and converted to digital datas through AID converter. These digital datas are automatically saved in the external RAM of acquisition part. The computer takes the digital datas and calculates the electric displacement D, the electric field and the dielectric constant $\varepsilon$. We tested for PZT ceramic sample and could observed the D-E hysteresis lops and ${\varepsilon}_s$-E hysteresis loops with good forms.

• 설비공학논문집
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• 제26권11호
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• pp.512-521
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• 2014

Recently, multiple glazing units, frames, complex fenestration systems, and windows with shading devices have been developed to save cooling energy in buildings. However, very little work has been conducted on developing a direct experimental test method of the solar heat gain coefficient(SHGC) for new fenestration techniques. This study aims to develop and evaluate a test apparatus to measure the SHGC, according to the KS L 9107 test method. The performance of the solar simulator was class A, B, and A, for spectral match, non-uniformity, and instability irradiance, respectively. The differences between the measured and calculated SHGC values were found to range between 0.001 and 0.011, and for all test specimens they agreed within 4%. These results establish the validity of the test apparatus. This system is thus expected to be useful in assessing the energy performance for various types of fenestration.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.30-35
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• 2008

This paper describes a fault detection and diagnosis (FDD) system developed for the heat source apparatus in building air-conditioning system. As HVAC&R systems in building become complex and instrumented with highly automated controllers, the processes and systems get more difficult for the operator to understand and detect the mal-functions. Poorly maintained, degraded, and improperly controlled equipment wastes an estimated 15% to 30% of energy used in commercial building. When operating a complex facility, FDD system is beneficial in equipment management to provide the operator with tools which can help in decision making for recovery from a failure of the system. Automated FDD for HVAC&R system has the potential to reduce energy and maintenance costs and improves comfort and reliability. Over the last decade there has been considerable research for developing FDD system for HVAC&R equipment. However, they are being made too much of a theoretical study, so only a small of FDD methods are deployed in the field. This study deduced an actual defect source for the heat source apparatus and suggested a low price FDD method which is ready to be deployed in the field.

• 한국화재소방학회논문지
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• 제21권4호
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• pp.32-37
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• 2007

인화점의 정보를 확보하는 것은 화재 및 폭발의 예방을 위해 대단히 중요하다. 본 연구에서는 2-propanol+acetic acid 계와 2-propanol+n-propionic acid 계의 하부 인화점을 클리브랜드 개방식 장치를 이용하여 측정하였다. 실험값은 Raoult의 법칙, Wilson 식과 NRTL 식에 의해 계산된 값과 비교하였다. 그 결과, Wilson 식과 NRTL 식에 의한 예측값이 Raoult의 법칙에 의한 예측값 보다 실험값에 더욱 근접하였다. 또한, NRTL 식의 실험값에 대한 모사성이 Wilson 식의 그것 보다 우수하였다.

• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.43-54
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• 1997

Species, doses and routes extrapolation can be sucessfully carried out by using a physiologically-based pharmacokinetic (PBPK) approach. And PBPK approach to assess risk of hazardous chemicals is reasonable whatever the exposure scenarios are happened. Both partitioning coefficients of chemical between tissue and blood and enzymatic metabolic rate constants are key parameters to build up the PBPK model. In this study, we tried to estimate in vitro metabolic rate constants using a special apparatus instead to measure the in vivo constants which are used to PBPK simulation since the in vitro tests are less expensive and more convenient than in vivo tests. For the purpose, we designed and tested the new system to measure continuously the headspace concentration of VOC. The newly designed system is composed with a diffusion chamber which generates gaseous substrate, a reaction vessel with a recirculating pump to establish a closed system, an autbmatic sampler from a gas phase, a gas chromatography to analyze the headspace. In addition, a cold water condenser is attached between the reaction vessel and pump to reduce the content of gaseous moisture which interferes with chemical analysis. To validate the newly developed methodology, in vitro metabolic rate constants of trichloroethylene (TCE) as a prototype VOC were estimated by simulating observed results with an ACSL program. The simulated results are consistent to those estimated by the other research groups. This finding suggests that our newly designed closed system may be a useful apparatus to estimate in vitro metabolic rate constants for VOC.