• 설비공학논문집
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• 제18권3호
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• pp.225-230
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• 2006

The overall performance and local flow fields of the fan, heat sink, and fan-sink were experimentally and numerically studied to investigate the flow characteristics of a fan-sink. The flow resistance of the heat sink was measured by small fan tester based on AMCA standards and compared with the CFD results to select available cooling fan for the fan-sink. The nonuniform velocity profile behind the fan outlet was shown by the flow visualization. The effects of nonuniform velocities on the performance of heat sink were discussed. To validate the commercial CFD code CFX-5.6, the predicted performance curve was compared with that of fan testing. The local flow fields of the fan-sink were analyzed by CFD results. MFR (multiple frame of reference) was used as a computational model combining rotating fan and stationary heat sink. Through the CFD results of the fan-sink, the flow patterns behind the fan outlet influenced the flow resistance and overall performance of the heat sink.

• Environmental Analysis Health and Toxicology
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• 제17권2호
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• pp.95-107
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• 2002

This study was designed to investigate the characteristics of atmospheric concentrations of toxic volatile organic compounds (VOCs) in Korea. Target compounds included 1,3-butadiene, aromatics such as BTEX, and a number of carbonyl compounds. In this paper, as the first part of the study, the performance of sampling and analytical methods was evaluated for the measurement of selected VOCs and carbonyl compounds in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/MSD analysis, while carbonyls by the DNPH-silica cartridge sampling with HPLC analysis. The methodology was investigated with a wide range of performance criteria such as repeatability, linearity. lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal standards. In addition, the sampling and analytical methods established in this study were applied to real field samples duplicately collected in various ambient environments. Precisions for the duplicate samples appeared to be comparable with the performance criteria recommended by USEPA TO-17. The overall precision of the sampling and analytical methods was estimated to be within 20 ∼ 30% for major aromatic VOCs such as BTEX, whereas the precision for major carbonyl compounds such as formaldehyde and acetaldehyde was within 10 ∼ 20% for field samples. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

• Journal of Biosystems Engineering
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• 제39권1호
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• pp.21-33
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• 2014

Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the test procedures of the major standard development organizations (SDO's) remained unchanged or with a little modification over the years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, and comfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfort evaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve the current test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human error in the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration and converted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbar forces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, driving strategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulate pollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agricultural tractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Program and methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have been found to be very dependent upon the nature of field operation performed, and the test track techniques required development/adaptation to improve their suitability during standardized assessment. Emphasizes should be given to improve visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated under electromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in this paper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.151-152
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• 2019

This study length variation test, shock test were conducted to evaluate the performance of synthetic resin form. Results of both thermal length variation test and shock test satisfied the KS standards. for length variation test, the result of the horizontal and vertical valuse were -0.1% in average.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.55-60
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• 2003

As operating time of heat exchangers progresses, fouling generated by water-borne deposits increases and thermal performance decreases. The fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. The heat exchangers of nuclear power plants have been analyzed in terms of the heat flux and heat transfer coefficient at test conditions based on the ASME OM-S/G-Part 2 as a means of heat exchanger management. It is hard to estimate the heat performance trend and to establish the future management plan. This paper describes the fouling evaluation method which can evaluate the thermal performance for heat exchangers and estimate the future fouling variations and the plugging margin evaluation method which can reflect the current fouling level developed in this study. To develop the fouling and plugging margin evaluation methods for heat exchangers, fouling factor was introduced based on the ASME O&M codes and TEMA standards. For the purpose of verifying the two evaluation methods, the fouling and plugging margin evaluations were performed for a component cooling heat exchanger in a nuclear power plant.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.1-9
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• 2016

The warpage on mobile phone camera packages occurs due to the CTE(Coefficient of Thermal Expansion) mismatch between a thin silicon die and a substrate. The warpage in the optical instruments such as camera module has an effect on the field curvature, which is one of the factors degrading the optical performance and the product yield. In this paper, we studied the effect of die bonding epoxy on the package and optical performance of mobile phone camera packages. We calculated the warpages of camera module packages by using a finite element analysis, and their shapes were in good agreement showing parabolic curvature. We also measured the warpages and through-focus MTF of camera module specimens with experiments. The warpage was improved on an epoxy with low elastic modulus at both finite element analysis and experiment results, and the MTF performance increased accordingly. The results show that die bonding epoxy affects the warpage generated on the image sensor during the packaging process, and this warpage eventually affects the optical performance associated with the field curvature.

• 한국태양에너지학회 논문집
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• 제38권4호
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• pp.1-9
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• 2018

본 연구는 신규로 구축 된 장비의 정확성과 PVT 제품의 KS 기준의 방향성을 살펴보았다. 먼저 신규로 구축된 Indoor solar thermal simulator의 경우, 인공광의 빔 균일도와 분광 특성을 기존의 규격 조건을 충족되도록 설계했으며, 실제 시험을 통해 B 등급임을 확인하였다. Indoor solar thermal simulator 장비의 정확도는 상용 태양광 모듈 및 기존 상용 장비로 측정 후, 최대 전력값을 비교했으며 오차 값은 약 0.4%로 정확도가 높음을 확인하였다. PVT 제품의 효율은 기존의 태양광 모듈 KS 기준과 태양열 집열기 KS 기준을 준용하여 측정하면 될 것으로 보이며, PVT 제품의 구조적 특징인 열매체 냉각에 의한 추가 전기 효율 방법 개발은 필요해 보이며, 본 연구에서는 태양광 모듈 케이블의 단락 유무에 따른 효율 상승 차이를 살펴보았고 추가 전기 효율 측정 방법으로 가능성을 제시하였다. 다양한 PVT 모듈의 유형에 따라 특히, PVT 모듈 전면에 유리 커버 유무에 따라 출력 감소가 발생되고 추가 공정에 의해 전기 출력 특성이 달라지는 값을 고려하여 PVT 제품의 전기 효율 측정 시험은 인증을 받은 제품을 이용하여 제작을 했어도 반드시 재시험이 필요하다고 판단되며, 시험방법이 수립되어야한다. 마지막으로 PVT 제품의 내구성 평가를 경우, 기존의 태양광 모듈 및 집열기의 내구성 시험의 모든항목을 KS 인증 시험 항목에 포함 시켜야 된다고 판단되며, 제품의 특성에 따라 시험의 재배열을 추가 연구가 필요해 보이며, 집열기 부분의 내구성을 고려하여 합부 기준을 추가적으로 고려해야 한다고 판단된다.

• 대한의용생체공학회:의공학회지
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• 제43권3호
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• pp.147-152
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• 2022

This research is to measure real-time temperature distribution inside a tissue-mimicking phantom for the safety and effectiveness evaluations of focused ultrasound (FUS) device capable of linear scanning stimulation. Since the focusing area of the FUS stimulation device is smaller than diameter of conventional thermal probe and keeps moving, it is impossible to monitor temperature distribution inside the phantom. By using the phantom with a thin film temperature sensor array inserted, real-time temperature change caused by the FUS device was measured. The translation of the measured temperature peak was also tracked successfully. The present phantom had been experimentally proven to be applicable to validate the performance and safety of the therapeutic ultrasound devices.

• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.408-417
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• 2019

Non-destructive test techniques are becoming increasingly important for assessment and maintenance. These techniques are very useful for assessment of materials such as wood, whose performance can vary considerably depending on the conditions of use. It is possible to estimate some mechanical properties of a material by determining the movement of energy through the material with the help of these techniques. In this study, it was investigated whether the wood material could be tested nondestructively by the heat energy produced by a source. The correlations between the thermal conductivity and mechanical properties of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea L.) woods were investigated. The thermal conductivity (TC), density, modulus of rupture (MOR), compression strength (CS), and modulus of elasticity (MOE) values of samples were measured according to the related standards and these values were correlated with each other. The linear and multiple regression tests were employed to determine the correlation between thermal conductivity and mechanical properties. The results showed that there is a very strong correlation between thermal conductivity and both density and MOR values. However, the correlations between TC and both MOE and CS were moderate. The results of this study suggest that the thermal conductivity value can be used to estimate the density and some mechanical properties of wood.

• Journal of the Korean Wood Science and Technology
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• 제43권6호
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• pp.876-883
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• 2015

국립산림과학원에서는 한옥의 전통건축기술을 바탕으로 한국형 기둥-보 목조주택인 ?그린 프로젝트를 2006년부터 진행해오고 있다. 최근에는 에너지 절약 기술요소를 적용하여 건물의 에너지성능을 개선하고자 하였다. 본 연구에서는 강화된 단열기준에 따른 기둥-보 목조벽체의 단열상세를 제시하고 그에 따른 건물 에너지 절감 효과를 평가하고자 하였다. 건물외피의 열관류율은 현행법 수준과 저에너지주택인 패시브하우스 수준인 두 단계로 나누었으며 건물에너지 성능을 평가하기 위하여 건물의 기밀성능은 국내 신축 목조주택 수준인 $3.0h^{-1}$과 패시브하우스 수준이 $0.6h^{-1}$ 두 단계로 나누어 열관류율과 기밀성능의 조합에 따라 4가지 경우에 대한 건물에너지 성능 평가가 이루어졌다. 대상건물은 서울에 위치하였으며 에너지 성능은 상용 건물에너지성능 평가 프로그램인 CE3가 사용되었다. 강화된 열관류율에 따라 시뮬레이션을 진행한 결과 연간 난방에너지 요구량은 $14kWh/(m^2{\cdot}a)$ 절감효과를 나타냈다.