가정용 가스보일러 열교환기 유형에 따른 압력분포특성에 관한 연구

차경옥,오율권,최경석 한국산업안전학회 2001 한국안전학회지 Vol.16 No.4

Heat transfer and pressure distribution for heat exchanger type of domestic gas boiler are different from shape, pitch, thickness of fin and array of pipe respectively. In order to measure the pressure distribution across the heat exchanger, a suction type wind tunnel was constructed and velocity distribution was measured for pitot tube(4 point) of rack type. The experiments were performed for 5 different air flow mass, rpm=3,6,9,12,15 and transverse axis of heat exchanger(x-length) is 5㎝ respectively. Results showed that above 9.5m/s, pressure distribution dispersion for wet type of heat exchanger is on the increase and above 5.5m/s, pressure distribution dispersion for dry type of heat exchanger is on the increase. Also, pressure distribution dispersion by comparing two different types heat exchanger, dry type of heat exchanger showed a higher augmentation than wet type of heat exchanger.

방형파 펄스 가열에 의한 BaOTiO$_{2}$ SrOTiO$_{2}$, MgOTiO$_{2}$ 계열의 열물성치 측정에 관한 연구

차경옥,장희석,이흥주 한국자동차공학회 1991 오토저널 Vol.13 No.2

In this study, thermophysical properties of the ceramic dielectrics such as BaOTiO$_{2}$, SrOTiO$_{2}$, MgOTiO$_{2}$, were measured by a single rectangular pulse heating method. The values of thermal diffusivities, specific heats, and thermal conductivities were measured as a function of temperature range from room temperature to 1300k. The measured thermal properties of one group of ceramic material were compared with those of other group and discussed in detail in connection with the chemical composition. Thus, some criteria for thermal design with the electric-electronic ceramic material were proposed.

합성 고분자물질 A611P를 첨가한 기액 2상 수직상향의 유동특성에 관한 실험적 연구

차경옥,김재근,양회준 대한설비공학회 1998 설비공학 논문집 Vol.10 No.4

Two-phase flow phenomena are observed in many industrial facilities and make much importance of optimum design for nuclear power plant and the liquid transportation system. The particular flow pattern depends on the conditions of pressure, flow velocity, and channel geometry. However, the research on drag reduction in two-phase flow is not intensively investigated. Therefore, experimental investigations have been carried out to analyze the drag reduction and void fraction by polymer addition in the two-phase flow system. We find that the polymer solution changes the characteristic of two-phase flow. The peak position of local void friction moves from tile wall of the pipe to the center of the pipe when polymer concentration increase. And then we predict that it is closely related with the frau reduction.

直線핀에 대한 過渡熱傳達에 關한 硏究

車京玉 명지대학교 1983 明大論文集 Vol.14 No.-

The analysis of unsteady state heat transfer in the straight fin of rectangular cross section has been made by making use of the theory of finite difference method and variational method. The heat transfer coefficient in the fin is given as a function of position(x), ie h=(r+1)(x/L)^r(h_a), which was suggested by L.S Han and S.G Lefkowitz. And the results are compared with the analytical solution which was obtained by assuming the heat transfer coefficient to be constant. These results show good agreement between the solution of finite difference method and analytical solution in all dimensionless time(e=αE/L^2)domain. But the solution of variational method has been found to have discrepancies with analytical solution in the some region of dimensionless time domain. When the dimensionless number N(=[√(h_a,P)/(kA)]·L) is 0.5 and 1.0, the larger the dimensionless time(e), the larger the effect of an exponential (r) to the temperature distribution. On the other hand, in the range of small N(N≤0.01), the effect of exponential (r) to the temperature distribution has been found to be negligible. The efficiency of the fin having large number of N(N≥0.5), ie heat conductivity (k) is small and length(L) is long, is decreased as the exponential (r) is increased. And the fin having small number of N, ie heat conductivity (k) is large an length(L) is short, shows that the efficiency of fin is almost constant regardless the value of exponential (r). Nomenclature A; area of cross-section of fin a; dimensionless semithickness of fin(=(b)/(l)) B; Biot number(=hl/k) b; semithickness of fin C; specific heat of fin E; time (sec) e; dimensionless time(=(αE)/(L^2)) h; convective heat transfer coefficient h_a; average heat transfer coefficient k; thermal conductivity of material of fin L; length of fin N=√[(h_a·p)/(kA)]·L P; perimeter of fin Q; heat transfer rate T; temperature of fin T_o; fin base temperatures T_∞; convection fluid temperature x; distance from base of fin X; dimensionless distance from base of fin(=(x)/(L)) α; thermal diffusivity(=k/ρ·c) θ; dimensionless temperature(=(T-T_∞)/(T_o-T_∞)) ρ; density of fin [ ] ; square matrix

고차 통계해석을 이용한 결함이 있는 베어링에서 음향-진동 신호의 해석

이해철,차경옥 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

This paper present a study on the application of sound pressure and vibration signals to detect the presence of defects in a rolling element bearing using a statistical analysis method. The well established statistical parameters such as the crest factor and the distribution of moments including kurtosis and skewless are utilized in this study. In addition, other statistical parameters derived from the beta distribution function are also used. A comparison study on the performance of the different types of parameter used is also performed. The conditions, the statistical method can be used to identify the different types of defect present in the bearing. In addition, the results also reveal that there is no significant advantages in using the beta function parameters when compared to using kurtosis and the crest factor for detecting and identifying defects in rolling element bearings from both sound and vibration signals.

차량 배기계의 배기압 감응형 머플러 개발

이해철,차경옥 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

Setting the channel-switching phase of automobile control mufflers in low-speed region is effective measures to improve low-speed torque. A muffler sensing exhaust-gas pressure has been developed to solve this problem. This muffler reduces exhaust noise in a pair of tailpipes by generating interference through a reverse-phasing process. This reduces exhaust noise makes it possible to set the muffler's channel-switching phase in the low-speed region.

非定常熱源인 펄즈狀加熱法에 의한 强誘電體 Ceramic의 熱物性 測定

車京玉 明知大學校 産業技術硏究所 1992 産業技術硏究所論文集 Vol.11 No.-

The square wave pulse heating method of measuring thermophysical properties has been developed. The cylindrical of a specimen in the ferroelectricity ceramincs are heated square wave for a few second by a film heater which is placed between the plates. The resulting temperature history of the opposite surface is attached to make it hove high thermal and conductivites, is measured by pressing seperated C-A thermocouple wires against the surface. From a compassion between the measured and theoretical temperature histories, the thermal diffusivity, the specific heat and t conductivity of the specimen can be deformined automatically in a few minuted by a computer. The values of thermophysical properties were measured as a function of temperature ranging from room temperature to 1000℃ Thus, the effects of dielectricity upon themophysical properties were analyzied in detail.

機關 排氣系에서 非正常 가스流動의 壓力波豫測에 關한 硏究

李珉湖,梁振承,車京玉 明知大學校 産業技術硏究所 1998 産業技術硏究所論文集 Vol.17 No.-

This paper describes a theoretical and experimental investigation of the pressure-time histories of some basic internal combustion engine exhaust systems. The program package is utilized the method of characteristics to solve the general equations of one-dimensional unsteady gas flow. This analysis is then combined with boundary models, based on quasi-steady flow approach, to give a complete treatment of the flow behavior in the exhaust system. Using a rotary valve simulator, experimental pressure-time were obtained. The predictions are compared with measured results and show a high degree of correlation in amplitude and phasing.

전주 명인, 명가, 명소 음식점의 관계특성이 고객만족과 애호도에 미치는 영향 연구: 전주지역 소비자를 중심으로

차경옥,이대희 관광경영학회 2021 관광경영연구 Vol.102 No.-

In 2012, Jeonju was designated as the 4th UNESCO City of Gastronomy in the world. In 2016, its entire area was expansively re-certified as a Slow City. Owing to such influences, Jeonju surpassed 10 million domestic & foreign tourists. With this background, Jeonju City designated Jeonju food masters, reputable families, and attractions in 2006. In 2020, total 12 masters, reputable families, and attractions have been designated and managed. Thus, the objective of this study is to present the implications by analyzing differences and influence relations of relational characteristics, customer satisfaction, and customer loyalty, targeting total 198 consumers in Jeonju region with experiences of visiting nine masters, reputable families, and attractions except for masters and reputable families of Pyebaek, Kimchi, and Korean traditional sweets. Regarding the customers visiting Jeonju masters, reputable families, and attractions, the factors of relational characteristics such as ‘customer orientation’, ‘scale’, ‘reputation’, and ‘price’ had positive(+) effects on the customer satisfaction. The factor of relational characteristics highly explaining the customer satisfaction was ‘price’. Also, the customer satisfaction had positive(+) effects on the customer loyalty while the factors of relational characteristics also had positive(+) effects on the customer loyalty. The factor of relational characteristics highly explaining the customer loyalty was ‘price’, which was followed by ‘customer orientation’, ‘scale’, and ‘reputation’ in order. The significance of this study is to empirically analyze the relations of relational characteristics, customer satisfaction, and customer loyalty of Jeonju masters, reputable families, and attractions, targeting the consumers residing in Jeonju instead of tourists from other regions. Such Jeonju master, reputable family, and attraction restaurants should increase the revisit through the provision of price, staff training, and convenience space that could satisfy the customers residing in Jeonju. The results of this study presented the future direction for vitalizing the operation of shops by providing the basic data for business strategies of Jeonju master, reputable family, and attraction restaurants.

충진탑식 흡수 제습장치의 성능 특성에 관한 실험적 연구

이세용,차경옥 明知大學校 産業技術硏究所 2000 産業技術硏究所論文集 Vol.19 No.-

In this study, the performance characteristics of packed tower for absorption dehumidifier system using liquid desiccant was analyzed experimentally with packing materials. Operating parameters were solution temperature, solution flow rate, solution concentration, inlet air temperature, air absolute humidity, air flow rate. With experimental data, dehumidification rate, contact efficiency and absorbing potential were calculated. The result of this study suggested optimal design conditions for absorption dehumidifier system.