• Title/Summary/Keyword: Temperature Difference Measurement

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Sensitivity Analysis on KS and JIS Standard for Heat Recovery Ventilator (KS, JIS 열교환 환기장치 실험규격의 민감도 분석)

  • Yee Jurng-Jae;Ihm Pyeong-Chan;Kim Hwan-Yong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.11
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    • pp.998-1004
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    • 2005
  • Recently natural ventilation rate is decreased due to the airtightness of apartment building. Therefore the use of heat recovery ventilator (HRV) has been greatly increased as an alternative method to supply fresh air and save energy in the building. In this research the experiment standard of HRV is compared between KS and JIS and the sensitivity analyses are experimented by both standards. Under cooling experiment condition indoor and outdoor wet-bulb temperature difference of JIS is 2 to 3 times higher than that of KS. It shows that the efficiency measurement of HRV by KS is expected to have greater sensitivity than by JIS and thus accurate measurement of web-bulb temperature is required. The experimental results provide that the efficiency of thermal exchange is resemblance to each others between KS and JIS. Under cooling experiment condition the efficiency of humidity exchange by KS presents higher than by JIS, however, under heating experiment condition the efficiency by KS shows lower than by JIS, reversely.

A Study on Dynamic Characteristics Analysis of Hybrid Wind Power Blades according to Material Properties Method (물성치 적용 기법에 따른 하이브리드 풍력 블레이드 동적특성 해석에 관한 연구)

  • Kang, Byong-Yun;Han, Jeong-Young;Hong, Cheol-Hyun;Moon, Byong-Young
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.2
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    • pp.5-11
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    • 2012
  • In this paper, the heat transfer coefficient measurement techniques using TSP(temperature sensitive paint) were introduced and the results of a comparative study on the heat transfer coefficient measurement by steady state and transient TSP techniques were discussed. The distributions of heat transfer coefficient by a single $60^{\circ}$ inclined impingement jet on a flat surface were measured by both techniques. Tested Reynolds number based on the jet diameter (d) was 30,000 and the distance between jet exit and target plate (L) was fixed at 10d. Results showed that the measured Nusselt number by both techniques indicated significant difference except near the center of impingement jet. Also, the heat transfer coefficients measured by the transient TSP technique were affected by the reference temperature of the jet. Based on the measured data, characteristics of both TSP techniques were analyzed and suggestions for applying them were also given.

A Study on the Intensity Measurng of Ultrasonics by Added Two Sensive point of Thermocouple (이감온점 열전대에 의한 초음파의 강도측정에 관한 연구)

  • Kim, Ju-Hong;Lee, Dong-Hwi;O, Yeong-Don
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.8 no.6
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    • pp.1-7
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    • 1971
  • This paper describes concerning the method of measurement for the intensity of ultrasonics in liquid. The probe which is added two sensive point of thermocople which is surrounded by the absorbed material of sonic wave on the both side of the refleftite plate have measured the intensity of ultrasonics indirectly by the difference of the temperature of two sensive point which had raised the temperature by the sonic wave and its reflective wave which transmitted the ultrasonic energy. This minify the influence from the temparature of liquid and time constant. Consequently, this is the basic industrial method which is with in the bounds of possibility on the simple measurement of the intensity of the local ultrasonics concerning direction of its propagation.

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Evaluation of Natural Ventilation Performance using the Multi-Functional Floor Heating System (다기능온돌시스템을 이용한 자연환기성능 평가)

  • Cho, Dong-Woo;Yu, Ki-Hyung;Yu, Jung-Yeon;Jung, Hae-Kwon
    • Proceedings of the SAREK Conference
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    • 2007.11a
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    • pp.105-112
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    • 2007
  • Recently developed raised floor heating system is not only capable of basic function to reduce noise between floors, but also is a multi-functional floor heating system enabling natural ventilation. The procedure of this system for natural ventilation is to import outdoor air through bottom space of the floor heating system, circulate indoor space and discharge it out of ceiling. In winter, powerless natural ventilation is possible with buoyancy effect caused by temperature difference between outdoor and indoor. And it also allows saving of energy by importing pre-heated air in bottom space of the floor heating system. To evaluate ventilation performance of this system, on-site measurement was conducted in 2 test laboratories, and the nominal air change rate was satisfied as 0.4$\sim$0.8 h-1 under the condition of outdoor temperature $5^{\circ}C{\sim}-5^{\circ}C$, which was evaluated as highly possible to be applied as a natural ventilation system in multi-family houses.

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Difference between shrinkage rate of irradiation amount of 3D printing UV curable resin and shrinkage rate according to a constant temperature water bath (3D 프린팅용 UV 경화 수지의 조사량 및 항온수조 침적에 따른 수축률의 차이)

  • Kim, Dong-Yeon
    • Journal of Technologic Dentistry
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    • v.42 no.2
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    • pp.113-120
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    • 2020
  • Purpose: This study is to compare and analyze the shrinkage of the specimen after UV irradiation of UV cured resin at 5, 15, and 30 minutes. Methods: A cylindrical UV cured specimen was produced using a stainless steel mold. UV cured resin specimens were prepared in three groups: 5 minutes cured (5M), 15 minutes cured (15M), and 30 minutes cured (30M). The measurement was made in total 3rd. The measurement was made in total 3rd. The primary measurement was made after 24 hours using a digital measuring instrument. The 2nd and 3rd measurements were deposited in a constant temperature water bath and the shrinkage was measured. The measured data was calculated by referring to the ASTM C326 linear measurement calculation method. T-test and One-way ANOVA were performed to test the significance between groups. The post-test was conducted with Tukey (α=0.05). Results: When the inner diameter and the outer diameter of the three groups not placed in the water bath were compared and analyzed, the contraction was the smallest at 6.8% in the 5M group, and the contraction was the largest at 7.3% in the 30M group. In the outer diameter, the contraction of the 5M group was the smallest at 3.5%, and the contraction of the 30M group was the largest at 4.5%. Shrinkage decreased in all three groups immersed in a water bath for 3-7 days. Conclusion: In the UV cured resin specimen, the shrinkage increased as the amount of UV irradiation increased.

The Comparison of the EWT&LWT between Field Measurement and CFD of Vertical-type Geothermal Heat Exchanger (수직형 지열교환기의 입.출구온도에 대한 실측과 CFD 결과 비교)

  • Woo, Sang-Woo;Kim, Joong-Hun;Shin, Seung-Ho;Hwang, Kwang-Il
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.3 no.1
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    • pp.11-16
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    • 2007
  • The purpose of this study is to use the CFD(Computational Fluid Dynamics) method for the ground source heat pump(GSHP) system with vertical U-tube ground heat exchangers. In order to predict LWT(leaving water temperature) in the length of time, This simulation is used by utilizing FLUENT which is commercial CFD code. It was performed by based on four boreholes in the field. Comparing with the results of CFD and field measurement for LWT, the results of CFD was presented very good agreement with 1.0% average difference.

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A STUDY ON THE VOLUMETRIC EFFICIENCY OF HIGH SPEED MULTI-CYLINDER AND ROTARY COMPRESSOR (고속다기통 및 회전식 압축기의 체적효율)

  • OH Hoo Kyu;CHO Kweoun Ok
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.12 no.1
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    • pp.13-18
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    • 1979
  • Volumetric efficiency is a determining factor for tile measurement of compessor capacity, but it is practically hard to take an accurate measurement of capacity characteritics so that most of users trust the data of makers catalogue. We often realized the discrepancy in their data with actual capacity. This study was attemped to establish the basic data of capacity characteristics of compressor by measuring volumetric efficiency of high speed multi-cylinder compressor and rotary compressor. The volumetric efficiency was calculated based on the quantity of the flow of ammonia vapor and pressure difference in suction state of orifice plate and compressor. The volumetric efficiency of high speed multi-cylinder compressor was $37-61\%$ and that of rotary compressor was $57-82\%$ when compression ratio was in the range of 4-12. The discrepancy in volumetric efficiency at an equal evaporating temperature between the makers catalogue and the measured data was $5.5\%$.

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A Development of TIER-LII Sensor Head Design for Diesel Soot Size Measurement (디젤 soot의 크기 측정을 위한 TIER-LII 센서헤드 설계기술 개발)

  • Seo, Dong-Kyu;Kim, Deok-Jin;Chung, Jea-Woo;Yoon, Yeo-Seong;Lee, Chun-Beom
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.215-220
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    • 2004
  • The TIER-LII system was established and evaluated using carbon black for diesel particulate size measurement. It contains a new designed sensor head which makes it easier to be measured. Through LII signal analysis of some parameters, we can understand that there were few correlations observed in effect of temperature, shield gas flow rate, and mixture flow rate.. However, an amount of difference was observed in different size of particulates.

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A Study on thermal deformation behavior of laminates composed of different material layers. (다종 재료층으로 구성된 적층판의 열변형 거동 연구)

  • 정재한;구남서;박훈철;윤광준
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.11a
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    • pp.54-57
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    • 2000
  • Thermal deformation behavior has been investigated for unsymmetric laminates composed of various kinds of material layers, such as stainless steel, aluminum, carbon/epoxy or glass/epoxy. The thermal deformations of unsymmetric laminates were predicted using the classical lamination theory and compared with those obtained from experimental measurement. In the case of unsymmetric laminate composed of stainless steel and aluminum layer, the experimental results were agreed well with the values predicted. But in the case of unsymmetric laminate composed of fiber composite layers, there was a considerable difference of thermal deformation between the prediction and experimental measurement, which may be from the change of material properties of fiber composite layers for temperature variation.

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Optimize OTDOA-based Positioning Accuracy by Utilizing Multiple Linear Regression Model under NB-IoT Technology (NB-IoT 기술에서 Multiple Linear Regression Model을 활용하여 OTDOA 기반 포지셔닝 정확도 최적화)

  • Pan, Yichen;Kim, Jaesoo
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2020.07a
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    • pp.139-142
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    • 2020
  • NB-IoT(Narrow Band Internet of Things) is an emerging LPWAN(Low Power Wide Area Network) radio technology. NB-IoT has many advantages like low power, low cost, and high coverage. However low bandwidth and low sampling rates also lead to poor positioning accuracy. This paper proposed a solution to optimize positioning accuracy under the OTDOA(Observed Time Difference of Arrival) approach by utilizing MLR(Multiple Linear Regression) models. Through the MLR model to predict the influence degree of weather(temperature, humidity, light intensity and air pressure) on the arrival time of signal transmission to improve the measurement accuracy. The improvement of measurement accuracy can greatly improve IoT applications based on NB-IoT.

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