• 한국자동차공학회논문집
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• 제25권1호
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• pp.35-41
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• 2017

The use of engineering plastics in automotive components is increasing with the trend towards improving the car strength and reducing weight. Among the different choices of materials, engineering plastic emerged as the necessary material for achieving lower costs, reduced weight and improved production efficiency. To produce the automotive parts, it is important to predict defect and validation of injection molding prior to design. Injection molding analysis and structural analysis are widely applied as a part of the design process when developing automotive parts. Injection molding analysis, in particular, involves a highly complicated mechanism that requires deep knowledge of polymer properties as well as an analytic approach different from that used for a general isotropic material when the molded material is used as a structural material. This is because the parts made of polymer have pre-stress factors such as intrinsic deformation and residual stress. The most important factors for injection molded plastic products are injection molding condition and cavity design, taking into account ease of molding, mass production and application. Despite optimal injection molding conditions and cavity design, however, glass fiber orientation is critically linked to strength reduction. The application of injection molding and structural coupled analysis provides a low-cost solution for product molding and structural validation, all prior to the actual molding. The purpose of this study involves the validation, pre-study, and solution of defect in injection-molded polymer automotive parts using the simulation software for injection molding and structural coupled analysis. Finally, this thesis provides validation of an injection molding and structural coupled analytic mechanism that can demonstrate the effect of glass fiber orientation on mechanical strength. Design improvement ideas for the injection molded product of PPS (Poly Phenylene Sulfide)+40% glass fiber are also suggested.

• 한국산학기술학회논문지
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• 제21권9호
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• pp.144-150
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• 2020

본 논문에서는 국외에서 정의하는 자동화시험시스템과 자동화시험장비(ATE)의 비교를 통해 국내 ATE 재정립을 비롯해 국내 유도무기 분야의 ATE 현황을 살펴보면서 국방 분야 ATE의 유효성 확인 방안을 모색해 보았다. 국내 무기체계 개발단계 ATE 장비 유효성 확인 방안 모색을 위한 활동으로 국내 유도무기 분야의 ATE 장비 현황을 분석하고 ATE 유효성 확인 방안을 살펴보았다. 신규 제작되는 ATE에 대해 반복성, 재현성 확인 방안 및 현재 사용되는 ATE의 유효성 확인을 위하여 특정 유도제어부 영상성능에 대해 오류 주입시험을 수행해 보았다. 개발단계부터 유효성 확인을 위한 방안으로 ATE의 설계 및 구현시 사전점검단계 기능을 요구사항으로 반영되야 할 필요성을 논하였으며, 국내 ATE 개발 시 표준화된 국제표준시험시스템 테스트 스크립트 언어를 활용하여 효율적인 유효성 확인과 SW 신뢰성 확보 가능성을 검토해 보았다. 이를 통하면 장기적으로 주장비와 시험장비 간 상호 연동성을 확보할 수 있으며 시험자는 표준화된 시험방식을 지원하는 시험시스템 플랫폼을 확보할 수 있어 무기체계별 특정 ATE 유효성 확인에 효과적일 것으로 판단된다.

• 한국공간구조학회논문집
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• 제13권2호
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• pp.75-82
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• 2013

For each cable component in a cable dome structure, pre-tension is needed for stability of whole the structure. The summation of these pre-tension at each joint should be zero to achieve the self equilibrium structure. The first step in cable dome structure analysis is to find the ratio of pre-tension in each member which can produce a stable and structure on self-equilibrium. In this paper, a new method based on the basic principle of closed force polygon for equilibrium system is proposed for the determination of self-equilibrium mode of cable dome structure. A single layer cable dome and two multi layer type domes have been analyzed. The ratios of cable members are determined by the presented method, and check the validation of the results by numerical calculation.

• 도시과학
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• 제11권2호
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• pp.1-8
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• 2022

This study proposed how to identify window defects by using photos uploaded by occupants during the pre-handover inspection of mulch-family housing. A total of 1168 door images were acquired to generate training data and validation data. Subsequently, through the proposed algorithms, every pixel in images labeled a door was binarized using the OTSU threshold, and then dark pixels were identified as defects. Experimental results demonstrated that our computer vision-based defects identification method detects the door with a recall of 57.9%, and door defects with 63.6%. Although it is still a challenge to automatically identify building defects because of the distortion and brightness of photos, this study has the potential to support better defects management. Ultimately, the improved pre-handover inspection may lead to increased customer satisfaction.

• 한국융합학회논문지
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• 제11권2호
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• pp.331-339
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• 2020

본 연구는 예비교사에게 요구되는 미래 교사역량 진단도구를 개발하고 타당화하는 것을 그 목적으로 하였다. 본 연구에서 미래 교사역량으로 지식, 실천, 인성 등 3차원에서 각각 기초역량과 직무역량으로 위계화하여 가설모형을 설정하였다. 본 가설모형을 바탕으로 54개의 예비문항을 개발하였으며, J지역 237명의 예비교사를 대상으로 역량 진단검사를 실시하였다. 본 연구의 결과는 다음과 같다: 첫째, 본 연구의 결과 미래 교사역량은 지식 차원 6개 요인 18개 문항, 실천 차원 6개 요인 17개 문항, 인성 차원 6개 요인 18개 문항 등 총 53개 문항이 도출되었다. 둘째, 미래 교사역량 진단 모형의 적합성은 비교적 만족할 만한 수준이었고, 집중타당성과 판별타당성이 검증되었다. 본 연구의 결과에 따라 논의하였으며, 마지막으로 본 연구의 시사점 및 후속연구 제언을 제시하였다.

• 한국환경보건학회지
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• 제41권5호
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• pp.358-367
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• 2015

Objectives: This study was performed to evaluate the analytical method for PAH metabolites in human urine using enzyme hydrolysis and solid-phase extraction coupled with LC-(ESI)-MS/MS technique. Methods: We employed HPLC tandem mass spectrometry techniques with appropriate pre-treatment for analysis of 16 OH-PAHs in human urine. Samples were hydrolysis by ${\beta}$-flucuronidase/Aryl sulfatase, and target compounds were extracted by solid-phase extraction with a strata-x cartridge. Cross-validation was performed between Eulji University and Green Cross laboratories with 200 human urine samples. Results: The accuracies were between 90.3% and 118.8%, and precisions (relative standard deviations) were lower than 10%. The linearity obtained was satisfying for the 16 OH-PAH compounds, with a coefficient of determination ($r^2$) higher than 0.99. The results of cross-validation at the two organizations were compared by ICC (interclass correlation coefficient) values. The cross-validation results were excellent or good for all compounds. Conclusion: An analytical method was validated for low nanogram levels of 16 OH-PAHs in human urine. Also, satisfying results were obtained for method validation such as accuracy, precision and ICC of cross-validation.

• 한국초등과학교육학회지:초등과학교육
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• 제41권1호
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• pp.65-78
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• 2022

이 연구의 목적은 예비 교사들을 대상으로 과학적 자기 효능감 척도의 타당도 검증과 배경 변인에 따른 잠재평균분석을 통해 예비 교사 교육에서의 시사점을 도출하는 것이다. 이를 위하여 187명의 예비 교사들을 대상으로 과학적 자기 효능감 척도(Tark, 2011)를 활용한 사전 검사를 진행하였다. 그리고 탐색적 요인분석을 통해 도출한 결과를 바탕으로 전문가 협의회를 실시하여 문항을 보완한 후 354명의 예비 교사들에게 본 검사를 실시하였으며 탐색적 요인분석과 확인적 요인분석을 실시하였다. 분석 결과 사전 검사에는 과학적 자기 효능감 척도에 예비 교사들은 3개 요인으로 응답하였으나 2개 문항의 타당도가 낮게 나타났다. 수정한 척도를 활용하여 본 검사를 실시한 결과 29개 문항이 의도한 3개 요인에 적재되었음을 확인하였으며 각 요인별 신뢰도는 .882~.886으로 나타났다. 예비 교사들의 배경 변인에 따른 잠재평균분석을 실시하여 효과 크기를 도출한 결과, 성별에 따라서는 자기조절효능감(Cohen's d > .5)은 여성이 자신감(Cohen's d > .3)은 남성이 유의미하게 높은 결과를 보여주었다. 진로 계열과 과학에 대한 선호도 변인에서는 과제곤란도선호 요인과 자기조절효능감 요인에서 자연(이공)계열, 그리고 과학에 긍정적 선호를 선택한 예비 교사가 유의미하게 큰 효과크기 차이(Cohen's d > .8)를 보여주었다. 이 연구 결과를 토대로 수정된 과학적 자기 효능감 척도를 활용하면 예비 교사들의 과학 과목에 대한 자기 효능감을 정확히 진단하는데 큰 기여를 할 것이라 판단된다. 또한 과학적 자기 효능감 검사 결과를 바탕으로 예비 교사들의 과학적 자기 효능감을 효과적으로 향상시킬 수 있는 교육과정 및 교육 내용 개편에도 기여할 수 있을 것이다.

• 분석과학
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• 제37권2호
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• pp.114-122
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• 2024

A transmission Raman spectroscopy-based quantitative model, which can analyze the content of a drug product containing naproxen sodium as its active pharmaceutical ingredient (API), was developed. Compared with the existing analytical method, i.e., high-performance liquid chromatography (HPLC), Raman spectroscopy exhibits high test efficiency owing to its shorter sample pre-treatment and measurement time. Raman spectroscopy is environmentally friendly since samples can be tested rapidly via a nondestructive method without sample preparation using solvent. Through this analysis method, rapid on-site analysis was possible and it could prevent the production of defective tablets with potency problems. The developed method was applied to the assays of the naproxen sodium of coated tablets that were manufactured in commercial scale and the content of naproxen sodium was accurately predicted by Raman spectroscopy and compared with the reference analytical method such as HPLC. The method validation of the new approach was also performed. Further, the specificity, linearity, accuracy, precision, and robustness tests were conducted, and all the results were within the criteria. The standard error of cross-validation and standard error of prediction values were determined as 0.949 % and 0.724 %, respectively.

• Korean Journal of Radiology
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• 제24권7호
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• pp.626-639
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• 2023

Objective: To investigate the association of clinical, pathologic, and magnetic resonance imaging (MRI) variables with progressive disease (PD) during neoadjuvant chemotherapy (NAC) and distant metastasis-free survival (DMFS) in patients with triple-negative breast cancer (TNBC). Materials and Methods: This single-center retrospective study included 252 women with TNBC who underwent NAC between 2010 and 2019. Clinical, pathologic, and treatment data were collected. Two radiologists analyzed the pre-NAC MRI. After random allocation to the development and validation sets in a 2:1 ratio, we developed models to predict PD and DMFS using logistic regression and Cox proportional hazard regression, respectively, and validated them. Results: Among the 252 patients (age, 48.3 ± 10.7 years; 168 in the development set; 84 in the validation set), PD was occurred in 17 patients and 9 patients in the development and validation sets, respectively. In the clinical-pathologic-MRI model, the metaplastic histology (odds ratio [OR], 8.0; P = 0.032), Ki-67 index (OR, 1.02; P = 0.044), and subcutaneous edema (OR, 30.6; P = 0.004) were independently associated with PD in the development set. The clinical-pathologic-MRI model showed a higher area under the receiver-operating characteristic curve (AUC) than the clinical-pathologic model (AUC: 0.69 vs. 0.54; P = 0.017) for predicting PD in the validation set. Distant metastases occurred in 49 patients and 18 patients in the development and validation sets, respectively. Residual disease in both the breast and lymph nodes (hazard ratio [HR], 6.0; P = 0.005) and the presence of lymphovascular invasion (HR, 3.3; P < 0.001) were independently associated with DMFS. The model consisting of these pathologic variables showed a Harrell's C-index of 0.86 in the validation set. Conclusion: The clinical-pathologic-MRI model, which considered subcutaneous edema observed using MRI, performed better than the clinical-pathologic model for predicting PD. However, MRI did not independently contribute to the prediction of DMFS.

• 한국전산유체공학회지
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• 제9권2호
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• pp.62-69
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• 2004

The present work solved 3D incompressible RANS equations on a rotating, multi-blocked grid system to efficiently analyze ducted marine propulsor with the interaction of propeller guidevane and annular duct. To handle the interface boundary between the guidevane and the propeller, a sliding multiblock technique based on the cubic spline interpolation was applied. To validate the present code, a turbine flow was simulated and the time-averaged pressure coefficients were compared with experiment. After the code validation, the flowfield around a ducted marine propeller with pre-swirl guidevane was simulated.