• 한국항해학회지
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• 제23권2호
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• pp.29-42
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• 1999

An accurate method of estimating ship maneuverability needs to be developed to evaluate precisely and improve the maneuverability of ships according to the water depth. In order to estimate maneuverability by a mathematical model. The hydrodynamic forces acting on a ship hull and the flow field around the ship in maneuvering motion need to be estimated. The ship speed new the berth is very low and the fluid flow around a ship hull is unsteady. So, the transient fluid motion should be considered to estimate the drag force acting on the ship hull. In the low speed and short time lateral motion, the vorticity is created by the body and grow up in the acceleration stage and the velocity induced by the vorticity affect to the body in deceleration stage. For this kind of problem, CFD is considered as a goof tool to understand the phenomena. In this paper, the 2D CFD code is used for basic consideration of the phenomena to solve the flow in the cross section of the ship considering the ship is slender and the water depth is large enough. The flow fields Added and hydrodynamic forces for the some prescribed motions are computed and compared with the preliminary experiment results. The comparison of the force with measurement is shown a fairly good agreement in tendency. The 3D Potential Calculation based on the Hess & Smith Theory is employed to predict the surge, sway added mass and yaw added moment of inertia of hydrodynamic coefficients for M/V ESSO OSAKA according to the water depth. The results are also compared with experimental data. Finally, the sway added mass of hydrodynamic coefficients for T/S HANNARA is suggested in each water depth.

• 한국의학물리학회지:의학물리
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• 제16권2호
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• pp.97-103
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• 2005

본 연구에서는 몬테칼로 계산(MCNPX 2.4.0)을 이용하여 24MV 의료용 선형가속기에서 발생하는 이차중성자의 에너지분포와 선량계산을 수행하였다. 먼저 선형가속기 두부(head)에서 방출되는 광자와 중성자의 에너지분포를 계산하였으며, 이를 이용하여 물팬텀에서 광자와 중성자의 흡수선량을 계산하였다. 몬테칼로 계산결과 물표면에서 5cm까지 중성자의 흡수선량은 $0.66\~0.35mGy/photon\;Gy$로 나타났으며, 상호작용 자료를 이용한 근사적 계산결과는 전자평형 깊이에서 0.52mGy/photon Gy로 나타났다. 다른 연구결과들과 비교를 통하여 본 연구가 고에너지 선형가속기에서 발생되는 중성 자의 선량평가에 응용될 수 있음을 제시하였다.

• 한국정밀공학회지
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• 제27권5호
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• pp.75-84
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• 2010

The aim of this paper is to design the blank shape of SPFH 590 high strength steel for stamping of the center hinge of automotive via numerical analyses and experiments for multi-stages transfer forming process. Three-dimensional elasto-plastic finite element analyses for the transfer forming process with six stages were performed using a commercial code AUTOFORM V4.2. The influence of the blank shape on the formability and the shape conformity were quantitatively examined through the FE analyses. From the results of the FE analysis, a feasible shape of the blank and the forming load were estimated. Stamping experiments were carried out using the proposed blank shape. The results of experiments were shown that the center hinge parts with the desired shapes can be manufactured successfully as the proposed blank shape is used. Through the comparison of the results of the experiments with those of the analyses, it was shown that the estimation of blank shape using the FE analysis is a proper methodology to create a feasible shape of the blank for the center hinge of automotive.

• Journal of Radiation Protection and Research
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• 제12권1호
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• pp.34-39
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• 1987

X-선 발생장치 시설에 대한 방사선 차폐해석은 두가지 측면에서 고려된다. 먼저 1차 방사선과 누설방사선에 의한 영향을 고려하여야 하며 본 연구에서는 NCRP-49 및 51에 제시된 방법을 사용하였다. 둘째, 시설의 미로 출입구에서는 산란방사선에 의한 영향이 보다 중요한데, 본연구에서는 이 영향을 평가하기 위하여 Albedo 개념을 근거로 한 단순한 방법이 제시되었고, 이를 토대로 계산된 결과를 컴퓨터 코-드(MORSE-CG)의 계산치 및 실측된 결과와 비교하였다. 본 연구에서 제시된 방법에 의한 결과는 미로출입구 안쪽의 경우에 대한 해석에서는 약간의 오차를 보이고 있으나 미로출입구 문바깥에서는 비교적 잘 일치한다. 여기서 출입문바깥의 경우에 대한 해석이 방사선방어 측면에서 보다 중요하다는 관점에서 볼 때 이 방법은 의료용 또는 산업용의 X-선 및 감마선시설의 차폐설계 및 해석에 응용될 수 있을 것이라고 판단된다.

• 한국유체기계학회 논문집
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• 제7권1호
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• pp.17-23
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• 2004

Aeroacoustic characteristics of sirocco fan used in Over-The-Range (OTR) has been analyzed in this paper. A microwave hood combination over the gas range is short for the OTR. The flow phenomena of the double-sided sirocco fan was analyzed numerically and experimentally by using commercial code and three dimensional PIV for flow visualization. Also, microphone array is used in order to understand acoustic characteristics of OTR. Two dimensional unsteady flow and acoustic simulation is tried to qualitatively estimate the effects of tonal noise and broadband noise on the overall sound pressure level. It is found that tonal sound is generated from the strong interaction between the impeller and cutoff while broadband sound is generated from the strong secondary flows along the scroll surface. To reduce the noise level, the V-shape cut-off was applied to improve the sound quality by reducing tonal noise. So the peak noise at BPF (Blade Passing Frequency) was almost reduced. The shape of flow-guide to suppress the secondary flow over the scroll surface was carefully checked. It is found that this affects flow pattern at the fan exit and reduces the broad band noise. Through this numerical and experimental study, the sound pressure level was lowered by 4dBA compared to that of the previous fan at the operating point.

• Structural Engineering and Mechanics
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• 제22권5호
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• pp.541-562
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• 2006

This paper compares the performance of axially loaded concrete filled steel tube (CFST) columns cast using a conventionally vibrated normal concrete (NC) and a novel self-consolidating concrete (SCC) made with a new viscosity modifying admixture (VMA). A total of sixteen columns with a standard compressive strength of about 50 MPa for both SCC and NC were tested by applying concentric axial load through the concrete core. Columns were fabricated without and with longitudinal and hoop reinforcement (Series I and Series II, respectively) in addition to the tube confinement. The slenderness of the columns expressed as height to diameter ratio (H/D) ranged between 4.8 and 9.5 for Series CI and between 3.1 and 6.5 for Series CII. The strength and ductility of SCC columns were found comparable to those of their NC counterparts as the maximum strength enhancement in NC columns ranged between 1.1% and 7.5% only. No significant difference in strain development was found due to the presence of SCC or NC or due to the presence of longitudinal and hoop reinforcement. Biaxial stress development in the steel tube as per von Mises yield criterion showed similar characteristics for both SCC and NC columns. The confined strength ($f^{\prime}_{cc}$) of SCC was found to be lower than that of NC and $f^{\prime}_{cc}$ also decreased with the increase of slenderness of the columns. Analytical models for the prediction of confined concrete strength and axial strength of CFST columns were developed and their performance was validated through test results. The proposed models were found to predict the axial strength of CFST columns better than existing models and Code based design procedures.

• 자동차안전학회지
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• 제8권3호
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• pp.10-15
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• 2016

The purpose of this study is to evaluate the injury mechanism of facial injury related to an air-bag's deployment in occupant motor vehicle accident (MVA) by using Hospital Information System (HIS) and reconstruction program, based on the materials related to motor vehicle accidents. Among patients who visited the emergency department of Wonju Severance Christian Hospital due to motor vehicle accidents from August 2012 to February 2014, we collected data on patients with agreement for taking the damaged vehicle's photos. After obtaining the verbal consent from the patient, we asked about the cause of the accident, information on vehicle involved in the accident, and the location of car repair shop. The photos of the damaged vehicle were taken on the basis of front, rear, left side and right side. Damage to the vehicle was presented using the CDC code by analytical study of photo-images of the damaged vehicle, and a trauma score was used for medical examination of the severity of the patient's injury. Among the 309 patients with agreement for an investigation, thirty five (11.3 %) were the severe who had ISS over 15. And also, sixteen (5.2%) derived from the reconstructed data (maximum collision energy, maximum acceleration, delta V) by PC-Crash. As a result, ISS including the facial injuries was affected by the condition. It was high when the number of crash extent, the safety belt was not fastened, and the seating position of occupant and the direction of collision is same. For accurate analysis of the relationship between occupant injury and vehicle damage in MVAs, build-up of an in-depth database through carrying out various policies for motor vehicle accidents is necessary for sure.

• 한국수소및신에너지학회논문집
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• 제10권2호
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• pp.107-118
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• 1999

MCFC 발전 기술의 실용화를 위하여 $3,000cm^2$ 면적의 단위전지 20장으로 구성된 5 kW 급 MCFC 스택을 5,760 시간 동안 운전하여 그 운전특성을 파악하였다. 스택은 7.6 kW의 출력을 보여주어 설계치보다 높은 출력을 보여주었다. 아울러 스택 성능 및 스택내 운전온도 분포변화를 해석하기 위하여 열전달, 유동방정식 및 연료전지 반응특성을 고려한 수학적 모델을 완성하였다. 완성된 수학적 모델 전산 모사를 위하여 상용 CFD 코드를 이용한 프로그램을 개발하였고 개발된 스택 전산모사 코드는 실제 운전된 5 kW MCFC 스택 운전 자료와 이론적 계산결과와 비교하여 그 신뢰성을 확인하였다.

• 한국실내디자인학회논문집
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• 제14권3호
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• pp.20-27
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• 2005

The built-in kitchen that is seen in every household is one of the achievements of the modernism architecture in early 20th century. Developed on the basis of two axis, one of which is the high industrialization and the other the sceptical assessment on the traditional value-system, the 20th century was launched in the form of the twofold entanglement, through the unfolding of which the cultural code of the modernism could be operated. The Quantification of the psychic that was attempted by H. v. Helmholtz and E. Mach in the pursuit of the reunification of sensation to the normal science was the first thread of that, while the second the break-down of the authoritative ideology and the emancipation of woman labour, which were initiated by the leftist movements. In this situation Margarete Schutte-Lihotzky was the woman architect who has tried to overcome the patriarchism in the household through architectural work by dwelling on that the emancipation of the housewives from the inefficient household labour is directly connected with the accomplishment of human freedom. She applied the modernist functionalism to the designing the kitchen for that purpose and outlined the effective range and operational realm of the rationalization. After all this the future preoccupying endeavor became the decisive moment that gave birth to a aesthetically and functionally good deliberated design of the kitchen in the present. This study is purposed to actualize the architectural ideas of Lihotzky into the present context through the consideration on the Frankfurt Kitchen of her and to grope for the relationship between architecture and feminism on the common horizon of the functionalist architecture and the women's liberation.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.834-839
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• 2000

The structural properties that SEM photograph of ZnO varistors surface studied by fractal mathematics program were investigated to verify the relations of electrical characteristics. The SEM photograph of ZnO varistors surface were changed by binary code and the grain shape of that were analyzed by fractal dimension. The void of ZnO varistors surface was found by fractal program. The relation between grain density and electrical properties depend on fractal dimension. The grain size in ZnO varistors surface was decreased by increasing of Sb$_2$O$_3$ addition. The spinel structure was formed by Sb$_2$O$_3$addition and it was depressed the ZnO grain formation. The grain size of ZnO by Sb$_2$O$_3$addition were from 5 to 10[${\mu}{\textrm}{m}$]. Among of ZnO varistors, fractal dimension of ZnO4 was very high as a 1.764. The density of grain boundary in ZnO2 and ZnO3 varistors surface was 15[%] by formed spinal structure. The breakdown electric field of ZnO2 that fractal dimension has 1.752 was very high to be 8.5[kV/cm]. When the fractal dimensin was high, the grain shape of ZnO varistors was complex and the serial layers of ZnO grain was increased.