• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.492-497
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• 2005

In this study, we propose an advanced nanoindentaion test, Nano Pillar Compression Test (NPCT) to measure a stress-strain relation for micro scale polymer structures. Firstly, FEM analysis is performed to research behavior of micro polymer pillars in several specimen aspect ratios and different friction conditions between specimen and tip. Based on the FEM results, micro scale UV-curable polymer pillars are fabricated on a substrate by Nano Stereo Lithography (NSL). To measure their mechanical properties, uniaxial compression test is performed using nanoindentation apparatus with flat-ended diamond tip. In addition, the dependency of compression properties on loading condition and specimen size are discussed.

• 항공우주기술
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• 제2권2호
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• pp.1-10
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• 2003

비행선은 주익이 없고 미익에 비해 동체 효과가 큰 형상 특성으로 인해 정적으로 불안정한 특성을 지닌다. 따라서 동안정 특성 예측이 매우 중요하다. 본 연구에서는 강제진동 풍동시험을 통한 비행선의 동안정 특성을 확보하였다. 풍동시험은 미국 BAR사의 독일소재 시설인 BAR LAMP 시설을 사용하였으며, 16회의 정적시험과 26회의 강제진동시험을 수행하였다. 시험결과, 비행선의 동안정 특성은 받음각 뿐만 아니라 옆미끄럼각, 각속도 크기와 방향에 비선형적으로 변한다. 전반적으로 세 방향의 모멘트는 댐핑이 있는 것으로 나타났으며, 수직력과 측력, 교차성분은 불안정하게 나타났다. 조종면의 영향은 작은 것으로 나타났으나 옆미끄럼각의 영향은 완전히 비선형적으로 나타났다.

• 한국의상디자인학회지
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• 제15권2호
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• pp.43-56
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• 2013

The purpose of this study was to investigate adolescents' body esteem and clothing behaviors according to the sociocultural attitude toward appearance. The subjects were 750 adolescents in Daejeon and Chungnam province. The research method was a survey methodology and the measuring instruments consisted of sociocultural attitude toward appearance, body esteem, clothing behaviors, and subjects' demographics attributions. The data were analyzed by Cronbach's ${\alpha}$, factor analysis, cluster analysis, t test, $x^2$ test, ANOVA and Duncan's multiple range test, using SPSS program. The results were as follows. First, 2 dimensions(internalization and awareness) were emerged on the sociocultural attitude toward appearance, and adolescents were divided into 4 groups (unreceptive group, awareness group, internalized group, and receptive group) by the sociocultural attitude toward appearance. Second, there are some differences in adolescents' body esteem according to the sociocultural attitude toward appearance. Receptive group had the lower level on body esteem than unreceptive group. Third, there are significant differences in adolescents' clothing behaviors according to the sociocultural attitude toward appearance. Receptive group had the highest psychological dependency of clothing, clothing interest, clothing individuality, and clothing conformity among 4 groups.

• 대한조선학회논문집
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• 제52권5호
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• pp.407-417
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• 2015

For the more accurate prediction on manoeuvring performance of a ship at initial design phase, bare hull manoeuvring coefficients were estimated by RANS(Reynolds Averaged Navier-Stokes) based virtual captive model tests. Hydrodynamic forces and moment acting on the hull during static drift and harmonic oscillatory motions were computed with a commercial RANS code STAR-CCM+. Automatic and consistent mesh generation could be implemented by using macro functions of the code and user dependency could be greatly reduced. Computed forces and moments on KCS and KVLCC 1&2 were compared with the corresponding measurements from PMM(Planar Motion Mechanism) tests. Quite good agreement can be observed between the CFD and EFD results. Manoeuvring coefficients and IMO standard manoeuvres estimated from the computed data also showed reasonable agreement with those from the experimental data. Based on these results, we could confirm that the developed virtual captive manoeuvring model test process could be applied to evaluate manoeuvrability of a ship at the initial hull design phase.

• ETRI Journal
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• 제32권1호
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• pp.73-83
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• 2010

Combinatorial testing has been an active research area in recent years. One challenge in this area is dealing with the combinatorial explosion problem, which typically requires a very expensive computational process to find a good test set that covers all the combinations for a given interaction strength (t). Parallelization can be an effective approach to manage this computational cost, that is, by taking advantage of the recent advancement of multicore architectures. In line with such alluring prospects, this paper presents a new deterministic strategy, called multicore modified input parameter order (MC-MIPOG) based on an earlier strategy, input parameter order generalized (IPOG). Unlike its predecessor strategy, MC-MIPOG adopts a novel approach by removing control and data dependency to permit the harnessing of multicore systems. Experiments are undertaken to demonstrate speedup gain and to compare the proposed strategy with other strategies, including IPOG. The overall results demonstrate that MC-MIPOG outperforms most existing strategies (IPOG, IPOF, IPOF2, IPOG-D, ITCH, TConfig, Jenny, and TVG) in terms of test size within acceptable execution time. Unlike most strategies, MC-MIPOG is also capable of supporting high interaction strengths of t > 6.

• 인터넷정보학회논문지
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• 제17권5호
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• pp.89-95
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• 2016

In a software testing domain, test case prioritization techniques improve the performance of regression testing, and arrange test cases in such a way that maximum available faults be detected in a shorter time. User-sessions and cookies are unique features of web applications that are useful in regression testing because they have precious information about the application state before and after making changes to software code. This approach is in fact a user-session based technique. The user session will collect from the database on the server side, and test cases are released by the small change configuration of a user session data. The main challenges are the effectiveness of Average Percentage Fault Detection rate (APFD) and time constraint in the existing techniques, so in this paper developed an intelligent framework which has three new techniques use to manage and put test cases in group by applying useful criteria for test case prioritization in web application regression testing. In dynamic weighting approach the hybrid criteria which set the initial weight to each criterion determines optimal weight of combination criteria by evolutionary algorithms. The weight of each criterion is based on the effectiveness of finding faults in the application. In this research the priority is given to test cases that are performed based on most common http requests in pages, the length of http request chains, and the dependency of http requests. To verify the new technique some fault has been seeded in subject application, then applying the prioritization criteria on test cases for comparing the effectiveness of APFD rate with existing techniques.

• 대한수의학회지
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• 제45권1호
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• pp.29-37
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• 2005

13-week orally repeated dose toxicity was investigated to ascertain the toxic effects of Aristolochiae radix in F344 rats at dose levels of 0, 1 (0.003 AA, aristolochic acid, mg/kg), 5 (0.014 AA mg/kg), 25 (0.068 AA mg/kg), 125 (0.34 AA mg/kg), and 500mg/kg (AA 1.36 mg/kg). No mortalities were found in any of the dose groups including vehicle control groups of both sexes during the study period. Hematologic and serum biochemical examinations revealed no changes related to the test item in any of the dose groups of both sexes. However, gross findings at necropsy implicated thickening of the stomach wall. In histopathological examinations, prominent findings related to the test item treatment were observed in the stomach and urinary bladder. There were squamous cell papilloma, squamous cell hyperplasia, ulceration and erosion observed in the non-glandular stomach. Squamouse cell hyperplasia was observed at dose levels of more than 125 mg/kg in both sexes and squamous cell papilloma was observed at dose level of 500 mg/kg in both sexes. The incidence and severity of these proliferating lesions including squamous cell hyperplasia and squamous cell papilloma increased with dose dependency. Transitional cell hyperplasia was also observed in the urinary bladder at dose levels of more than 25 mg/kg in both sexes and the incidence and severity of the lesion increased with dose dependency. In conclusion, the toxic changes related to the test item treatment were observed in the stomach and urinary bladder, and the no-observed-adverse-effect level (NOAEL) was estimated to be 5 mg/kg/day for both males and females in F344 rats.

• 한국의류학회지
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• 제29권5호
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• pp.715-726
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• 2005

The purpose of this study was to identify the effects of the sensation seeking and body image on female adolescents' clothing behavior and hair style attitude. The data was collected from 390 high school girls living in Seoul, via a self·administered questionnaires, and were analyzed by frequency, factor analysis, reliability test, Pearson's correlation, and multiple regression. The results of this study was as follows : 1) Three factors of body images were self appearance evaluation, appearance orientation and fitness orientation. Five factors of clothing attitudes were fashion/clothing interest, clothing exhibition, social approval, psychological dependence on clothing and fashion leadership. And three factors of hair style attitudes were interest in hair style, individuality in hair style and dependency on hair designer. 2) As the result of analyzing the effects of sensation seeking and body image on clothing behavior, fashion/clothing interest was explained by appearance orientation and fitness orientation, and clothing exhibition by sensation seeking and appearance orientation, and social approval by appearance orientation, self appearance evaluation and body cathexis, and fashion leadership by appearance orientation, fitness orientation and self appearance evaluation, and clothing conformity to the self-entertainer by appearance orientation, sensation seeking and fitness orientation, and appearance related delinquency by sensation seeking, appearance orientation, fitness orientation, self appearance evaluation. 3) As the result of analyzing the effects of sensation seeking and body image on hair style attitudes, interest in hair style was explained by the factors such as appearance orientation, sensation seeking, fitness orientation, and body cathexis, and individuality in hair style by appearance orientation, sensation seeking and self appearance evaluation, and dependency on hair designer by body cathexis.

• 대한토목학회논문집
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• 제33권1호
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• pp.93-100
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• 2013

본 연구에서는 트윈박스 단면인 이순신대교의 레이놀즈수 변화에 따른 공기력의 영향을 살펴보는데 그 목적이 있다. 이를 위하여 1/30 대축척 모형을 제작하여 공군사관학교 아음속 중형 풍동에서 최대 풍속 70m/s까지 풍속을 증가시켜가면서 공기력을 측정하여, 전북대학교 소형풍동에서 수행한 저레이놀즈수 풍동실험 결과와 비교하였다. 본 연구 대상 교량 단면은 레이놀즈수의 영향을 받는 것으로 나타났으며, 고레이놀즈수 실험 결과 기존 저레이놀즈수 실험보다 항력계수는 약 23%정도 낮은 수준인걸로 나타났다. 또한 경계층 촉진장치를 효과적으로 이용하면 기존의 저레이놀즈수 풍동실험 조건에서 고레이놀즈수 모사 실험이 가능한 것으로 판단된다.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.387-394
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• 2020

A parametric study of a 2.5 kW class propeller type micro hydraulic turbine was performed. In order to analyze the internal flow characteristics in the hydraulic turbine, three dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used and the hexahedral grid system was used to construct computational domain. To secure the reliability of the numerical analysis, the grid dependency test was performed using the grid convergence index method based on the Richardson extrapolation, and the grid dependency was removed when about 1.7 million nodes were used. For the parametric study, the axial distance at shroud span (L) between the inlet guide vane and the runner, and the inlet and outlet blade angles (β₁, β₂) of the runner were selected as the geometric parameters. The inlet and outlet angles of the runner were defined in the 3 spans from the hub to tip, and a total of 7 geometric parameters were investigated. It was confirmed that the outlet angles of the runner had the most sensitive effect on the power and efficiency of the micro hydraulic turbine.