• International Journal of Quality Innovation
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• 제9권1호
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• pp.22-40
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• 2008

Unnatural working postures usually cause musculoskeletal problems for workers in work field, especially in traditional industry. Many analysis and survey methodologies have been developed to identify unnatural postures and disorder risks in workplaces. The Ovako Working Posture Analyzing System (OWAS) and Nordic Musculoskeletal Questionnaire (NMQ) are the representative methods and applied widely. This study applied the both tools to investigate the work field of a manufacturing factory of the water heater's case. We divided the manufacturing process into nine workshops, took the pictures of working motions by DV camera and analyzed the postures on OWAS. From the OW AS results, we could identify the risks level of musculoskeletal symptoms as four Action Categories (AC). And from the comparison of OWAS and NMQ results, we could provide the suggestions to improve the working methods and environment. From the results of OWAS, we found that the operators' head/neck and back were above AC3 in some workshops. If the situation continued in long period, the operators might have the risk to get musculoskeletal symptoms. From the investigation of NMQ, we also found that the percentage of aches on neck, shoulders and lower back were higher than other parts of body. The correlation between aches and jobs was more than 75%. So we provided some suggestions to improve: work rotation and adjustment of work surface/height to fit in with Ergonomics. Then the risks of musculoskeletal symptoms would be reduced.

• Asian Pacific Journal of Cancer Prevention
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• 제17권sup3호
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• pp.205-211
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• 2016

Excessive exposure to chemicals in the workplace can cause poisoning and various diseases. Thus, for the protection of labor, it is necessary to examine the exposure of people to chemicals and risks from these materials. The purpose of this study is to evaluate semi-quantitative health risks of exposure to harmful chemical agents in the context of carcinogenesis in a latex glove manufacturing industry. In this cross-sectional study, semi-quantitative risk assessment methods provided by the Department of Occupational Health of Singapore were used and index of LD50, carcinogenesis (ACGIH and IARC) and corrosion capacity were applied to calculate the hazard rate and the biggest index was placed as the basis of risk. To calculate the exposure rate, two exposure index methods and the actual level of exposure were employed. After identifying risks, group H (high) and E (very high) classified as high-risk were considered. Of the total of 271 only 39 (15%) were at a high risk level and 3% were very high (E). These risks only was relevant to 7 materials with only sulfuric acid placed in group E and 6 other materials in group H, including nitric acid (48.3%), chromic acid (6.9%), hydrochloric acid (10.3%), ammonia (3.4%), potassium hydroxide (20.7%) and chlorine (10.3%). Overall, the average hazard rate level was estimated to be 4 and average exposure rate to be 3.5. Health risks identified in this study showed that the manufacturing industry for latex gloves has a high level of risk because of carcinogens, acids and strong alkalisand dangerous drugs. Also according to the average level of risk impact, it is better that the safety design strategy for latex gloves production industry be placed on the agenda.

• 한국산업보건학회지
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• 제26권3호
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• pp.301-306
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• 2016

Objectives: Direct-reading instrument(Photoionization detectors, PID) and quantitative analysis using active type air sampling (Gas chromatography-flame ionization detector, GC-FID) were tested to evaluate their ability to detect volatile organic compounds(VOCs) in a semiconductor manufacturing plant. Methods: The organic compounds used were acetone and ethanol which are normally used as cleaning solutions in the semiconductor manufacturing. The evaluation was based on the preparation of test solutions of known acetone and ethanol concentration in a chamber($600{\times}600{\times}1150mm$). Samples were prepared that would be equivalent to 5~100 ppm for acetone and 10~ 200 ppm ethanol. GC-FID and PID were evaluated simultaneously. Quantitative analysis was performed after sampling and the direct-reading instrument was checked using real-time data logging. Results: Positive correlations between PID and GC-FID were found for acetone and ethanol at 0.04~2.4% for acetone(TLV: 500 ppm) and 0.1~8.3% for ethanol(TLV: 1000 ppm). When the sampling time was 15 min, concentration of test solution was the most similar between measurement methods. However, the longer the sampling time, the less similar the results. PID and GC-FID had similar exposure patterns. Conclusions: The results indicate that PID and GC-FID have similar exposure pattern and positive correlation for detection of acetone and ethanol. Therefore, PID can be used for exposure monitoring for VOCs in the semiconductor manufacturing industry. This study has significance in that it validates measuring occupational exposure using a portable device.

• 품질경영학회지
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• 제43권4호
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• pp.589-606
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• 2015

Purpose: In developing new products, reducing performance variation is important for competitiveness factors such as quality, cost, and delivery. This paper aims at evaluating three performance variations; measurement, performance evaluation, and manufacturing variations, and then improving product and process design, focused on paper helicopter making case study. Methods: For measurement system analysis, gage R&R (repeatability and reproducibility), linearity, stability are evaluated. Since gage R&R are not satisfactory, the measurement system is improved by adopting voice memos application of iPhone and providing standard measurement procedure. To evaluate performance variation, product deterioration and environment factor (wind speed) is considered. Since the existing design is sensitive to these noise factors, a new product design is developed, which is proven to be robust to the noise factors. Finally, manufacturing variations are evaluated with five factors which can cause variation in flight time. To reduce the impact of three significant factors, three improvement methods are applied. Results: Three performance variations are evaluated and robust paper helicopter design is presented. Conclusion: To reduce measurement and process variations, improved measurement method and paper helicopter making procedure are proposed. A new product design is also presented which is robust to deterioration and environmental variation. This paper is expected to benefit students and practitioners who want to have hands-on knowledge on new product quality improvement.

• 한국시뮬레이션학회논문지
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• 제20권3호
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• pp.1-10
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• 2011

본 연구에서는 반도체, 디스플레이 등과 같은 첨단 전자제품 제조 시스템에서의 공정별 기계 대수를 결정하는 용량계획 문제를 고려한다. 제조 시스템은 공정별로 동일한 병렬기계가 존재하는 혼합흐름공정의 형태를 갖고 있으며, 각 기계 마다 서로 다른 제품 종류를 연속적으로 가공할 때는 셋업 작업이 발생한다. 설비를 구매할 수 있는 예산에 제약이 있는 상황에서 제조시스템의 생산율을 최대화 할 수 있는 공정별 기계 대수 조합을 결정해 주고자 한다. 혼합흐름공정 형태의 복잡한 제조시스템을 대상으로 주문이 동적으로 도착하고 여러 가지 일정계획방법을 적용하는 것을 모델링 하기 위하여 시뮬레이션 모델을 개발하였다. 본 연구에서는 시뮬레이션 실행을 포함한 다양한 조합의 기계 대수 증감 휴리스틱 방법을 제안하여 해를 도출하였다. 제안된 방법들은 일련의 계산실험을 통하여 그 성능을 비교 평가하였다.

• The Journal of Advanced Prosthodontics
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• 제13권5호
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• pp.327-332
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• 2021

PURPOSE. The purpose of this in vitro study was to evaluate the accuracy of digitally designed removable partial denture (RPD) frameworks, constructed by additive and subtractive methods castable resin patterns, using comparative 3D analysis. MATERIALS AND METHODS. A Kennedy class III mod. 1 educational maxillary model was used in this study. The cast was scanned after modification, and a removable partial denture framework was digitally designed. Twelve frameworks were constructed. Two groups were defined: Group A: six frameworks were milled with castable resin, then casted by the lost wax technique into Co-Cr frameworks; Group B: six frameworks were printed with castable resin, then casted by the lost wax technique into Co-Cr frameworks. Comparative 3D analysis was used to measure the accuracy of the fabricated frameworks using Geomagic Control X software. Student's t-test was used for comparing data. P value ≤ .05 was considered statistically significant. RESULTS. Regarding the accuracy of the occlusal rests, group A (milled) (0.1417 ± 0.0224) showed significantly higher accuracy than group B (printed) (0.02347 ± 0.0221). The same results were found regarding the 3D comparison of the overall accuracy, in which group A (0.1501 ± 0.0205) was significantly more accurate than group B (0.179 ± 0.0137). CONCLUSION. In indirect fabrication techniques, subtractive manufacturing yields more accurate RPDs than additive manufacturing.

• 항공우주시스템공학회지
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• 제13권1호
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• pp.54-61
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• 2019

3D프린팅은 '12년 세계경제포럼에서 떠오르는 10대 기술 중 2번째로 선정이 되었고 기존 산업의 패러다임을 변화시켜 제조업 혁신과 신 시장을 창출할 핵심기술로 대두되었다. 미국 등 주요 선도 국가들은 3D 프린팅을 국방 분야에 적극 확대해 나가고 있으며, 우리나라 역시 3D 프린팅의 군사적 활용을 위해 국방 수리부품 생산기술 확보 및 국방전문인력 양성을 추진하고 있다. 이에 본 논문은 기존의 무기체계 개발단계, 양산단계, 운영유지단계의 부품 국산화 개발관리 절차를 활용하여 향후 신뢰성 있는 3D 프린팅 수리부품을 효율적으로 작전현장에 적용하기 위한 방안을 제시하였다.

• 식품과학과 산업
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• 제49권4호
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• pp.94-99
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• 2016

식초는 신맛을 내는 역할에 집중되어 개발되고 산업화되어 발효 식초보다는 합성 식초가 발달하였다. 최근 다양한 영양성분을 함유하고 있는 발효 식초에 대한 소비자들의 관심이 발효 식초 산업의 성장을 증가시키고 있다. 미용에 관심이 많은 여성소비자들을 겨냥한 파인애플, 자몽, 알로에 등 다양한 외국산 과일을 사용하는 식초가 개발되어 판매되고 있으나, 쌀과 같은 지역 특산물을 이용하는 전통 발효 식초는 과일 식초에 비하여 성공적인 상업화가 드문 편이다. 따라서 지역에서 생산되는 다양한 농산물을 활용하여 부가가치가 높은 기능성 식초 제품을 개발하고 상업화하기 위한 보다 체계적인 기반 연구가 필요하다. 본 연구에서는 우리나라의 고문헌을 바탕으로 전통 발효 식초의 종류와 제조방법에 대해서 고찰하였다. 우리나라 고유의 전통발효 식초 제품을 개발하기 위한 연구가 필요한 것으로 사료된다.

• 품질경영학회지
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• 제52권1호
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• pp.77-93
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• 2024

Purpose: The purpose of this study is to examine machine learning use cases in manufacturing companies from a digital quality management (DQM) perspective and to analyze and present machine learning research patterns from a quality management perspective. Methods: This study was conducted based on systematic literature review methodology. A comprehensive and systematic review was conducted on manufacturing papers covering the overall quality management process from 2015 to 2022. A total of 3 research questions were established according to the goal of the study, and a total of 5 literature selection criteria were set, based on which approximately 110 research papers were selected. Based on the selected papers, machine learning research patterns according to quality management were analyzed. Results: The results of this study are as follows. Among quality management activities, it can be seen that research on the use of machine learning technology is being most actively conducted in relation to quality defect analysis. It suggests that research on the use of NN-based algorithms is taking place most actively compared to other machine learning methods across quality management activities. Lastly, this study suggests that the unique characteristics of each machine learning algorithm should be considered for efficient and effective quality management in the manufacturing industry. Conclusion: This study is significant in that it presents machine learning research trends from an industrial perspective from a digital quality management perspective and lays the foundation for presenting optimal machine learning algorithms in future quality management activities.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.125-133
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• 2002

In this study, it was investigated about endurance limit and fatigue behavior of load carrying fillet welded cruciform joints according to welding methods of SMAW, SAW, MIG and FCAW commonly using for welding structures in present. Endurance limit carried omit highly in the order of SMAW, MIG, SAW, FCAW and fatigue crack propagation ratio carried out lowly in the order of SMAW, MIG, FCAW, SAW. By these results, it is needed to use SMAW or MIG welding methods for welding structures with small welding capacity and SAW or FCAW methods for large welding structures after due consideration about economic gains and operation efficiency of welding. Fatigue crack propagation ratio is more effected by strength of welding materials than endurance limit of welding materials according to welding methods.