• 한국소음진동공학회논문집
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• 제25권2호
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• pp.75-82
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• 2015

Noises from the large scale marine propeller are calculated numerically on non-cavitation condition. The hydrodynamic analysis is carried out by potential based panel method with time marching free wake approach. The distribution of hydrodynamic loads on the propeller surface and noise signals are obtained using the unsteady Bernoulli's equation and the Farasssat's formula respectively. It turns out that the noise signal at the narrow band shows strong peak at the blade passage frequency, and the peak value at the 1/3 octave band also shows the same trend. Noise signals and directivity patterns for both the thickness and the loading noise are compared with each other. The directivity pattern for the loading noise shows minor lobe at the backward side of the rotating disc plane.

• 한국의류학회지
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• 제30권8호
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• pp.1210-1221
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• 2006

The strength of the PB(Private Brand) is that it can eliminate intermediary in the distribution channel and thoroughly control the quality under its own name. This study has developed traditional studies on private brand proneness in approaching data processing and empirical point of view of a consumer's attitude buildup process on PB through 'recognition-attitude-action(behavioral attitude)'. The subjects of this study are consumers in their $20s{\sim}40s$ who are main customer groups of PBs. A screening process has taken place to select consumers with purchasing experiences of retailor PBs. The data is analyzed by 'Structural Equation Modeling' of Amos 5.0 to verify consumer attitude formation model on private apparel brand. The results generated from this study are as follows: First, the proposed consumer attitude model on private apparel brand consists of store evaluation, experiential product evaluation, cognitive product evaluation, hedonic attitude, utilitarian attitude and purchase intention. Second, not only positively influence on utilitarian attitude but hedonic attitude can arouse positive emotional reaction of a consumer. Third, the store evaluation is ahead of the product evaluation because PB is more related to the image of a store. The influence of the store on PB is relatively stronger when compared with NB.

• 한국항공우주학회지
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• 제33권1호
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• pp.93-103
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• 2005

나노위성 HAUSAT-2 설계 검증의 일환으로 소형위성의 초기개념설계를 위한 시스템 엔지니어링 설계 도구를 개발하였다. 본 프로그램은 위성의 임무 및 사용자 요구조건을 바탕으로 탑재체와 각 서브시스템의 설계 과정을 거치면서 위성 전체 시스템의 질량 및 전력을 산출하고 설계된 시스템의 제작비용을 예측할 수 있다. 약 200여개의 소형위성 분석 데이터를 포함하고 있으며, 데이터베이스는 소형위성의 경향 분석을 제공할 뿐만 아니라 중요한 설계 요소로 쓰이고 있다. SEDT는 약 10개 이상의 소형위성 데이터를 경우에 따라 적용하면서 검증되었다.

• 설비공학논문집
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• 제20권9호
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• pp.571-580
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• 2008

In this work, pool boiling heat transfer coefficients(HTCs) of 5 refrigerants of differing vapor pressure are measured on horizontal smooth square surface of 9.52 mm length. Tested refrigerants are R123, R152a, R134a, R22, and R32 and HTCs are taken from $10\;kW/m^2$ to critical heat flux of each refrigerant. Wall and fluid temperatures are measured directly by thermocouples located underneath the test surface and by thermocouples in the liquid pool. Test results show that pool boiling HTCs of refrigerants increase as the heat flux and vapor pressure increase. This typical trend is maintained even at high heat fluxes above $200\;kW/m^2$. Zuber's prediction equation for critical heat flux is quite accurate showing a maximum deviation of 21% for all refrigerants tested. For all refrigerant data up to the critical heat flux, Stephan and Abdelsalam's well known correlation underpredicted the data with an average deviation of 21.3% while Cooper's correlation overpredicted the data with an average deviation of 14.2%. On the other hand, Gorenflo's and lung et al.'s correlation showed only 5.8% and 6.4% deviations respectively in the entire nucleate boiling range.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1489-1492
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• 2007

Belousov-Zhabotinsky (BZ) reaction containing oxalic acid and acetone as a mixed organic substrate catalyzed by Ce(IV) in a flow system has been investigated. The reaction system is analyzed by varying flow rate, inflow concentrations, and temperature. Interchangeable oscillating patterns are observed in a certain range of concentrations, and above or below the condition a steady state is obtained. The increase in temperature increases the frequency and decreases the amplitude of oscillations. The apparent activation energy for the system is calculated by using the Arrhenius equation, which means that temperature has a greater effect on the reaction. Bifurcation phase diagrams for the system show the region of oscillations or steady states along with a small region of multistability. Further the behavioral trend observed in this system is discussed by mechanistic character of the system.

• Nuclear Engineering and Technology
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• 제17권2호
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• pp.116-128
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• 1985

본 논문에는 이산화 우라늄 소결체의 노내고밀화현상을 온도와 미세구조의 함수로 정화하게 예측할 수 있는 기계론적 이론 모형이 개발.기술되어있다. 이 모형은 $UO_2$ 소결체의 결정 입계내에서 공극(vacancy)이 생성 이동되고, 결정입계에서 공극이 소멸되는 현상을 고려하고 있으며, 이 과정에서 일어나는 고밀화의 크기가 핵분열율, 조사시간, $UO_2$ 소결체밀도, 기공 크기의 분포, 결정입크기 및 온도의 함수로 기술되어 있다. 본 모형의 기공 수축에 대한 결과식은 Assmann과 Stehle가 유도한 4개의 온도 영역에 대한 결과식과는 상이한 것으로서, 소결체의 모든 온도 영역에 직접 적용된다. 본 모형에 의한 노내고밀화 크기의 예측치는 실험자료와 아주 잘 일치하며, KEFDA 전산코드에 사용된 경험적 실험 연산식에 비하여 고밀화의 경향과 절대치를 보다 정확히 예측한다.

• Environmental Engineering Research
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• 제24권4호
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• pp.600-607
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• 2019

Volatile organic compounds (VOCs) are released from various sources and are unsafe for human health. Porous materials are promising candidates for the adsorption of VOCs owing to their increased ratio of surface area to volume. In this study, activated carbon (AC) impregnated cellulose acetate (CA) electrospun mats were synthesized using electrospinning for the removal of VOCs from the air mixture of ACs, and CA solution was electrospun at different proportions (5%, 10%, and 15%) in a single nozzle system. The different AC amounts in the electrospun mats were distributed within the AC fibers. The adsorption capacities were measured for acetone, benzene, and dichloromethane, using quartz crystal microbalance. The results elicited an increasing adsorption capacity trend as a function of the impregnation of ACs in the electrospun mats, while their capacities increased as a function of the AC concentration. Dichloromethane resulted in a faster adsorption process than acetone and benzene owing to its smaller molecular size. VOCs were desorbed with the N₂ gas purging, while VOCs were adsorbed at higher temperatures owing to the increased vapor pressures. The adsorption analysis using Dubinin-Astakhov equation showed that dichloromethane is more strongly adsorbed on mats.

• 설비공학논문집
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• 제17권8호
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• pp.729-735
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• 2005

In this study, external condensation heat transfer coefficients (HTCs) were measured on a horizontal smooth tube at the saturated vapor temperature of $30^{\circ}C,\;39{\circ}C,\;and\;50^{\circ}C$ for R22, R410A, R407C, and R134a with the wall subcooling of $3\~8^{\circ}C$. The HTCs of all refrigerants are the highest at $30^{\circ}C,\;39{\circ}C,\;and\;50^{\circ}C$ in order. This trend is due to its excellent thermodynamic properties of the liquid phase. The measured data of HTCs were compared with the calculated ones by Nusselt's equation for a smooth tube. Measured HTCs of R22, R134a, R410A are $4.2\~7.5\%$ higher than prediction respectively while those of R407C are $15.6\~28.9\%$ lower than the prediction.

• 설비공학논문집
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• 제8권3호
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• pp.375-385
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• 1996

Turbulent flow and heat transfer characteristics around staggered tube banks were studied using the 3-D Navier-Stokes equations and energy equation governing a steady incompressible flow, which were reformulated in a non-orthogonal coordinate system with cartesian velocity components and discretized by the finite volume method with a non-staggered variable arrangement. The predicted turbulent kinetic energy using RNG $k-{\varepsilon}$ model was lower than that of standard $k-{\varepsilon}$ model but showed same result for mean flow field quantities. The prediction of the skin friction coefficient using RNG $k-{\varepsilon}$ model showed better trend with experimental data than standard $k-{\varepsilon}$ model result. The inclined flow showed higher velocity and skin friction coefficient than transverse flow because of extra strain rate ($\frac{{\partial}w}{{\partial}y}$). Also, this was why the inclined flow showed higher local heat transfer coefficient than the transverse flow.

• 한국산림과학회지
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• 제71권1호
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• pp.27-32
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• 1985

한 임분(林分)에 있어서 개체목(個體木)의 생장(生長)은 그 임목(林木) 주변(周邊)의 주변목(周邊木)들에 의하여 커다란 영향(影響)을 받는다. 무간벌(無間伐) 임분(林分)의 경우 이러한 경향(傾向)은 임목(林木) 상호간(相互間)의 경쟁(競爭)을 통하여 더욱 현저(顯著)하게 나타난다. 본(本) 연구(硏究)는 1962년(年) Spurr가 제안(提案)한 각도합산법(角度合算法)(angle-summation method)을 이용(利用)하여 낙엽송림(落葉松林)의 개체목(個體木) 생장(生長)과 주변목(周邊木)들과의 기본적(基本的)인 생장관계(生長關係)를 조사(調査)하였으며, 이것을 기초(基礎)로 중심목(中心木)으로 선정(選定)된 각(各) 임목(林木)들의 최근(最近) 5년간(年間)의 직경생장량(直徑生長量)을 추정(推定)하기 위해 중회귀식(重回歸式)을 적용(適用)하고 그 결과(結果)를 분석(分析) 검토(檢討)하였다.