열전대에 의한 화재유동의 온도측정에 관한 검토 - 측정오차

김성찬 한국화재소방학회 2010 한국화재소방학회논문지 Vol.24 No.6

A series of fire experiments have been performed to examine the measurement bias of the bare bead thermocouple widely used in fire testing and analyze the measurement bias of bare bead thermocouple comparing with the measured temperature using the aspirated thermocouple. The measured temperature of the bare bead thermocouple was lower than that of the aspirated thermocouple in the hot upper layer while it showed opposite trends in the upper layer. Also, the bare bead thermocouple showed higher measurement bias in the lower layer rather than upper layer in the compartment fire. The maximum relative percentage error of the bare bead thermocouple against the aspirated thermocouple reached 250% in the present study. The present study points out the need of correction process of the measured temperature by bare bead thermocouple for improving the reliability of the fire tests. 본 연구는 화재실험에서 널리 이용되고 있는 노출비드형 열전대의 신뢰성을 평가하기 위해 화재실험을수행하고 흡입식 열전대와 노출비드형 열전대에 의해 측정된 온도를 비교 분석한다. 화재실의 고온의 상층부에서는 노출비드형 열전대의 측정온도가 흡입식 열전대에 비해 상대적으로 낮게 나타났고 측정오차는 크지 않은 반면 저온의 하층부에서는 노출비드형 열전대의 온도가 높게 나타났으며 측정오차 또한 크게 증가하였다. 본 연구에서 측정된 노출비드형 열전대의 최대 상대오차는 최대 250% 이상까지 나타났으며 노출비드형 열전대를 이용하여 화재유동장을 정량화 할 때 측정 신뢰성 향상을 위해 적절한 보정과정이 필요함을 보여준다.

Development of a Device Equipped with a Thermocouple for Measuring Nasal Airglow

Chung, Seung Kyu,Koh, Seok Joo,Lim, Hyun Joon Korean Rhinologic Society 2000 Journal of rhinology Vol.7 No.1

Study of Impact Type Surface Junction Thermocouple

Sangha Park,Gisu Park 한국추진공학회 2020 Journal of Propulsion and Energy Vol.1 No.1

In this study, a coaxial thermocouple subjected to impact through a junction manufacturing process was investigated. The performance of the impact-type coaxial thermocouple was analyzed through impact and thermal tests to evaluate the resistance of the thermocouple to external forces and heat. In addition, shock tunnel experimental tests were conducted to assess the durability of the thermocouple in a hypersonic environment. The findings indicated that the impact-type coaxial thermocouple exhibited satisfactory resistance to external heat. Moreover, the results exhibited sufficient repeatability, and the performance of the impact-type coaxial thermocouple was determined to be comparable to that of the conventional coaxial thermocouple.

유속 및 열전대 위치의 영향을 고려한 열경계층 내부의 복합열전달 해석

이주안(Ju-An Lee),전병진(Byoung-Jin Jeon),최형권(Hyoug-Gwon Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

The error in measuring temperature profiles by thermocouple inside boundary layer mostly comes from the conduction heat transfer of the thermocouple. The error is not negligible when the conductivity of the thermocouple is very high. In this study, the effect of conduction heat transfer of the thermocouple on the temperature profile inside boundary layer was examined by considering both free-stream velocity and a thermocouple position. The conduction error of an E-type thermocouple was investigated by numerical analysis of three-dimensional conjugate heat transfer for various velocity profiles of boundary layer and thermocouple positions.

유속 및 열전대 위치의 영향을 고려한 열경계층 내부의 복합열전달 해석

전병진(B.J. Jeon),이주안(J.A. Lee),최형권(H.G. Choi) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1

The error in measuring temperature profiles by thermocouple inside boundary layer mostly comes from the conduction heat transfer of the thermocouple. The error is not negligible when the conductivity of the thermocouple is very high. In this study, the effect of conduction heat transfer of the thermocouple on the temperature profile inside boundary layer was examined by considering both free-stream velocity and a thermocouple position. The conduction error of an E-type thermocouple was investigated by numerical analysis of three-dimensional conjugate heat transfer for various velocity profiles of boundary layer and thermocouple positions.

온도 경계층 측정용 열전대 센서 개발

서종범(Jongbeom Seo),한상조(S. Han) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.12

본 연구에서는 등온 벽에서 가까이에 위치한 유동과 같이 온도 구배가 큰 곳에서 발생하는 전도오차를 줄이기 위해 새로운 열전대의 형상 설계 및 제작 방법을 제안하고자 한다. 전도오차를 줄이기 위하여 지름이 79.9 μm 인 열전대를 이용했으며, 아크 용접을 통해 제작된 상대적으로 접점이 큰 일반 열전대와 다른 butt-welded 열전대를 제작하기 위하여 용접용 5 축 장비가 고안됐다. 열전대의 단면을 맞닿게 하여 용접해 접합부위 크기를 최소화 했다. 온도 보정 실험을 통하여, 일반적인 형상의 열전대와 이 연구에서 제안하는 열전대의 온도 측정 결과가 동일함을 알 수 있었다. 접합부가 79.9 μm 지름을 가지는 butt-welded 열전대를 온도 경계층에 침투시켜서 전도에 의한 오차를 최소화하여 급격히 변하는 온도 경계층의 온도를 효과적으로 측정할 수 있게 되었다. 개발된 센서를 이용하여 선형 터빈 날개가 장착된 풍동에서 온도 경계층을 측정하였고, 측정된 결과를 Nusselt 수로 나타내었다. This research focused on designing an appropriate thermocouple sensor for a thermal boundary layer with a large temperature gradient. It was designed to minimize the conduction error from a constant temperature wall in a boundary layer. A 79.9-μm thermocouple was chosen, and a five-axis device jig was developed to fabricate a buttwelded thermocouple, which is different from arc-welded junction thermocouples. This was used to minimize the size of the thermocouple junction. In addition to fabricating butt-welded thermocouples, a thorough calibration was conducted to decrease the internal error of a multimeter to ensure that the data from the butt-welded and regular thermocouples were almost the same. Based on this method, a butt-welded thermocouple with a small junction was found to be suitable for measuring the temperature in a thermal boundary layer with very large thermal gradients. Using this thermal boundary layer probe, the thermal boundary layers in a turbine cascade were measured, and the Nusselt numbers were obtained for the turbine endwall.

Determination of Target Motion by Using a Respiration Monitoring Mask for 4-D Radiotherapy

정태식,임상욱,박성호,안승도,이병용,이상훈,조광환,장지선,권수일,조삼주,허현도,신동호,서태석,김철용,이석 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

The normal tissue toxicity encountered in lung cancer radiotherapy is frequently due to large treatment margins. The organ motion due to respiration necessitates that large margins be added to the planning target volume (PTV) to ensure adequate dose coverage in the chest and abdomen. Many techniques have been developed to minimize the irradiated volume of normal tissue, including gated radiotherapy, breath-holding techniques, and motion adaptive radiotherapy. If these techniques are to be utilized effectively, the precise four-dimensional (4-D) localization of a moving tumor must be available in real time. The aim of this study is to develop a simple, useful respiration-monitoring mask (ReMM) that identifies respiration-induced organ motion during the clinical application of 4-D radiotherapy. A thermocouple was embedded in a dust-proof mask and connected to a thermocouple module, which amplified the signal from the thermocouple. The dust-proof mask and the thermocouple were used to measure the respiratory movements of the patient during radiation therapy. Three patients and three healthy volunteers were enrolled to investigate the utility of the ReMM. The thermocouple measured the temperature of the mask during respiration. The diaphragmatic motion along a craniocaudal direction was simultaneously monitored using a uoroscope. The relationship between the respiratory pattern and the targeted motion along the craniocaudal direction was evaluated using a correlation coefficient. Respiration-induced target motion along a ventrodorsal direction was less than 5 mm for each patient. However, target motion along the craniocaudal direction was up to 3 cm in this study. The temperature in the mask does not drift more than 5 % of its maximum amplitude, even for a "held- time" of more than 10 seconds. The average correlation coefficients between the target motions during respiration along the craniocaudal direction and the ReMM signals were 0.91 for the eight cases. The ReMM signal showed strong correlation with the target motion, compared to the target motion in uoroscopy, despite irregular breathing. ReMM is a noninvasive breathing surrogate apparatus. Our study shows that the target motion correlates with the ReMM signal. However, no baseline-drifting problem exists in this system. The spirometer, the skin motion, and the strain gauge have been reported to have gradual drifting problems. The thermocouple is accurate and can be practically applied for monitoring respiration for the determination of target organ motion. The authors hope that the ReMM can be used in 4-D radiotherapy, such as gated radiation therapy, motion-adaptive radiation therapy, retrospective CT, and prospective CT.

복사 간섭 보정을 통한 초고온 가스 온도 측정 방법

김찬수(Chan-Soo Kim),홍성덕(Sung-Deok Hong),서동운(Dong-Un Seo),김용완(Yong-Wan Kim),이원재(Won Jae Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

When a thermocouple is placed in a high temperature gas-flow stream, the measured temperature could be biased from the true gas temperature due to a large radiation heat loss from a thermocouple surface to its surroundings. In this study, two thermocouples of unequal diameters with 1/8 inch and 1/16 inch are used to correct the radiation effect. The method is called the reduced radiation error (RRE). The preliminary test results show that the radiation and the sheath conduction cannot be negligible for the gas temperature measurement. To minimize the sheath conduction effect, all the thermocouples will have a grounded junction and 1/8 inch thermocouple will be replaced with 1 ㎜ thermocouples. In addition, the computational fluid dynamics code analysis shows that there is a negligible temperature difference between the positions where the thermocouples were installed.

열전대(thermocouple)를 이용한 Buchanan Plugger 표면의 온도상승 분석

조진숙,황윤찬,김선호,황인남,최보영,정영진,정우남,오원만 大韓齒科保存學會 2003 Restorative Dentistry & Endodontics Vol.28 No.4

This study was performed to evaluate the actual temperature rise on the surface of Buchanan plugger using thermocouple. The heat carrier system 'System B Heatsource'(Model 1005, Analytic Technologies, Redmond, WA, USA) and the Buchanan pluggers of F, FM, M and ML sizes are used for this study. The temperature was set to 200℃ on digital display and the power level on it was set to 10. Five thermocouples were placed in direct contact with the surface of each size of Buchanan's pluggers at 1 mm increments from the tip to the 4 mm length of shank. The heat control spring was touched for 5 seconds, and temperature rise on the surface of the pluggers were measured at 1 sec intervals for more than 5 seconds with an accuracy of 0.01 using Data Logger. The data were statistically analyzed by one-way ANOVA. The results were as follows. 1. The position at which the temperature peaked was approximately at 1~2 mm far from the tip of Buchanan plugger (p<0.01). 2. The peak temperature was 215.25±2.28℃ in F plugger, 185.94±2.19℃ in FM plugger, 169.51±9.12℃ in M plugger, and 160.79±1.27℃ in ML plugger and the peak temperature was highest in F plugger and followed by, in descending order, FM plugger, M plugger. ML plugger showed the lowest peak temperature (p<0.01). 3. The temperature on the pluggers was decreased with the increase of touching time. This results suggest that the actual temperature on the surface of the pluggers dose not correlate well with the temperature set on digital display. Heat concentrates around the up. The larger plugger reveals lower temperature rise relatively.

Hot Thermocouple법을 이용한 몰드플럭스의 결정화거동 평가

조중욱,김성연 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.3

A SHTT (single hot thermocouple technique) has been applied to measure crystallizing temperature and crystallizing rate of molten mold fluxes. It was possible to measure the crystallizing temperature and crystallizing rate of the commercial mold flux using a SHTT reliably, while the crystallizing temperature from DTA and the breaking temperature showed poor reliability. In SHTT, crystallizing temperature was measured at the continuous cooling speed of 100 K/min, and crystallizing initiation time at 1050℃. The crystallizing initiation time generally decreased for the mold flux of higher crystallizing temperature, and there is good interrelationship (R²=0.9588) between two. It is concluded that the SHTT should be considered as the method of quantifying the crystallization behaviors during continuous casting of steel.