• 한국건축시공학회지
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• 제7권1호
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• pp.99-106
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• 2007

Water leakage could be caused deterioration of environmental conditions, user condition, reduction of life span and long term safety in underground concrete structure. Many materials and construction method to repair on these problems have been developed, however, it is not proper to successful repair or raise problem of increasing repair cost However, there are many limitations as practical appraisal methods due to different view of reliability for test methods. Because, it was not enough that the technical objectivity could be lack and also application of environmental condition is inadequate. In this paper, we suggest varied test methods divided to appraisal for property of matter, construction, manufacturing, specification and maintenance, friendly environmental condition. It could be more practical as a objective standard considering various angles. In summery, it should be subdivided and differentiated to accomplish proper application and to select proper materials and construction method for repair even if the synthetical condition is very complicated.

• 한국생산제조학회지
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• 제23권5호
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• pp.485-497
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• 2014

This paper presents the robot vision control schemes based on the Newton-Raphson (N-R) and the Extended Kalman Filter (EKF) methods for the tracking of moving targets. The vision system model used in this study involves the six camera parameters. The difference is that refers to the uncertainty of the camera's orientation and focal length, and refers to the unknown relative position between the camera and the robot. Both N-R and EKF methods are employed towards the estimation of the six camera parameters. Based on the these six parameters estimated using three cameras, the robot's joint angles are computed with respect to the moving targets, using both N-R and EKF methods. The two robot vision control schemes are tested by tracking the moving target experimentally. Given the experimental results, the two robot control schemes are compared in order to evaluate their strengths and weaknesses.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.463-469
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• 2017

PURPOSE. To evaluate the fit of a three-unit metal framework of fixed dental prostheses made by subtractive and additive manufacturing. MATERIALS AND METHODS. One master model of metal was fabricated. Twenty silicone impressions were made on the master die, working die of 10 poured with Type 4 stone, and working die of 10 made of scannable stone. Ten three-unit wax frameworks were fabricated by wax-up from Type IV working die. Stereolithography files of 10 three-unit frameworks were obtained using a model scanner and three-dimensional design software on a scannable working die. The three-unit wax framework was fabricated using subtractive manufacturing (SM) by applying the prepared stereolithography file, and the resin framework was fabricated by additive manufacturing (AM); both used metal alloy castings for metal frameworks. Marginal and internal gap were measured using silicone replica technique and digital microscope. Measurement data were analyzed by Kruskal-Wallis H test and Mann-Whitney U-test (${\alpha}=.05$). RESULTS. The lowest and highest gaps between premolar and molar margins were in the SM group and the AM group, respectively. There was a statistically significant difference in the marginal gap among the 3 groups (P<.001). In the marginal area where pontic was present, the largest gap was $149.39{\pm}42.30{\mu}m$ in the AM group, and the lowest gap was $24.40{\pm}11.92{\mu}m$ in the SM group. CONCLUSION. Three-unit metal frameworks made by subtractive manufacturing are clinically applicable. However, additive manufacturing requires more research to be applied clinically.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1627-1635
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• 2001

Virtual manufacturing is a technology facilitating effective development and agile manufacturing of products via sophisticated computer models representing physical and logical schema and behavior of real manufacturing systems including manufacturing resources, environments, and products. For the successful application of this technology, a virtual plant as a well-designed and integrated environment is essential fur sharing information and engineering collaboration among diverse engineering activities. The systematic approaches and effective methods for construction and application of a virtual plant are proposed in this paper, such as a 3-D CAD modeling, cell and line simulations, databases and some information technologies. Measuring and 3-D CAD modeling technologies of many equipments, facilities and structures of the building are developed, and effective information management system managing CAD models, related files and data is implemented in WWW environments. Finally, precise simulations of unit cell lines and the whole plant are performed. For the beginning of implementing a Virtual Automotive Plant, the Virtual Plant fur the Body Shop of a Korean automotive company is constructed and implemented. We could obtain the benefit of savings in time and cost in many manufacturing preparation activities in the new car development processes.

• 한국산업보건학회지
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• 제27권4호
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• pp.423-432
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• 2017

Objectives: This study was conducted to evaluate asbestos handling history of workers at automobile manufacturing plants in Korea. Methods: National regulations on asbestos and Korea Occupational Safety and Health Agency(KOSHA) database on the information of asbestos containing products were reviewed. We investigated asbestos related materials from one automobile manufacturing plant. Material safety data sheets(MSDS) collected in 2010, work environment monitoring results reported from 2000 to 2013, trade union reports and asbestos survey reports were reviewed. We also interviewed workers with long career and did walk-through survey. Results: The Ministry of Labor in Korea has permitted asbestos manufacturing since 1990. In 1997, the use of crocidolite and amosite asbestos were banned. In 2007, the Korean government announced a total ban on the manufacturing, importation and use of all kinds of asbestos, which took full effect in 2009. A total of 174 asbestos products information from KOSHA database was analyzed. Extruded cement panel for building, special brake for crane farm machinery, gasket, joint sheet and thermal insulator were produced until 2007. From automobile manufacturing plant survey, we confirmed that asbestos containing materials(ACM) such as gasket, heating induction materials have been used until 2011. Asbestos containing building materials(ACBM) such as bamlites, slate and ceiling tex were reported at 122 asbestos dismantling projects in 2014. Conclusion: Although the use of all kinds of asbestos were banned from 2009, ACMs and ACBMs installed before 2009 were still found at automobile manufacturing plant until 2011 and 2014 respectively. In particular, asbestos slates should be managed because most of slates had not been removed until 2014.

• 디지털융복합연구
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• 제11권11호
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• pp.265-278
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• 2013

본 연구는 대기업의 공급자관계(SR, Supplier Relationship)의 협력활동이 중소기업의 생산역량과 기업성과에 미치는 영향에 관한 연구이다. 국내 대기업 215개사의 협력업체의 응답결과를 SPSS 21.0 및 AMOS 21.0를 이용하여 분석하였다. 연구모형은 요인 적재치를 이용한 개념 신뢰도와 분산추출지수를 사용하였다. 협력활동과 생산활동 수행도는 협력업체의 생산역량과 성과에 영향을 미친다는 가설을 설정, 대기업과의 수급단계를 조절변수로 사용하였다. 분석결과, 대기업의 협력활동이 협력업체의 생산역량에 미치는 영향은 유의하지 않았다, 수급단계별로 분석한 결과는 다소 차이를 보여주었다. 1차협력업체의 경우, 대기업의 협력활동이 생산역량에 유의한 영향을 나타내며, 2 3차협력 업체의 경우, 협력활동에 의한 영향은 유의하지 않으며, 생산역량과 기업성과는 생산활동수행도에 의해서만 영향을 받는 것으로 나타났다. 따라서 본 연구의 분석결과를 토대로 우리사회의 핵심과제로 남아있는 중소기업의 경영 및 생존과 관련한 문제에 대해서 대 중소기업 상생에 기반한 내실있는 대기업의 협력활동과 정부의 동반성장정책을 복합적으로 운영할 수 있는 실질적인 동반성장 방향을 제시하고자 한다.

• 산업경영시스템학회지
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• 제44권2호
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• pp.140-152
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• 2021

During the shift from gasoline vehicles to electric ones, auto parts manufacturing companies have realized the importance of improvement in the manufacturing process that does not require any layout changes nor extra investments, while maintaining their current production rate. Due to these reasons, for the auto part manufacturing company, I-company, this study has developed the simulation model of the PUSH system to conduct a process analysis in terms of production rate, WIP level, and logistics work's utilization rate. In addition, this study compares the PUSH system with other three manufacturing systems -KANBAN, DBR, and CONWIP- to compare the performance of these production systems, while satisfying the company's target production rate. With respect to lead-time, the simulation results show that the improvement of 77.90% for the KANBAN system, 40.39% for the CONWIP system, and 69.81% for the DBR system compared to the PUSH system. In addition, with respect to WIP level, the experimental results demonstrate that the improvement of 77.91% for the KANBAN system, 40.41% for the CONWIP system, and 69.82% for the DBR system compared to the PUSH system. Since the KANBAN system has the largest impacts on the reduction of the lead-time and WIP level compared to other production systems, this study recommends the KANBAN system as the proper manufacturing system of the target company. This study also shows that the proper size of moving units is four and the priority allocation of bottleneck process methods improves the target company's WIP and lead-time. Based on the results of this study, the adoption of the KANBAN system will significantly improve the production process of the target company in terms of lead-time and WIP level.

• 한국정보통신학회논문지
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• 제25권3호
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• pp.471-477
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• 2021

디스플레이 분야에 스마트 팩토리란 작업 자동화 뿐만 아니라 기존의 공정관리, 이동설비, 공정이상, 결함 분류 등에 AI/BIG DATA 기술을 이용한 보다 효율적인 디스플레이 제조를 의미한다. 과거 디스플레이 제조 과정에서 불량이 나오면 결함 분류, 공정 이상에 대한 대처가 시시각각 달랐기 때문에 이에 대한 많은 시간 소모가 발생했었다. 하지만 디스플레이 제조 분야는 고도화된 공정 장비를 이용해야 하고 불량 원인을 신속하게 파악해 수율을 올리는 것이 디스플레이 제조 산업의 경쟁력이다. 본 논문에는 스마트 팩토리 AI/BIG DATA 기술을 디스플레이 제조에 접목한 사례들에 대해 정리해 보고 기존 방법 대비 어떤 장점이 도출 되어질 수 있는지에 대해 처음으로 분석해 보고자 한다. 이를 통해 향후 AI/BIG DATA를 이용한 디스플레이 제조 분야에 보다 향상된 스마트 팩토리 개발을 위한 사전지식으로 활용하고자 한다.

• 한국기계가공학회지
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• 제5권1호
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• pp.7-12
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• 2006

Recently, the fractal interpolation methods have been widely introduced and used to estimate and analyze various theoretical and experimental data. Because of the chaotic behaviors of dynamic cutting force data, some method for end-milling force analysis must be used. The fractal analysis used in this paper is fractal linear interpolation and fractal dimension. Also, several methods for computing fractal dimensions have been used in which the fractal dimension of the typical dynamic end-milling force was calculated according to number of data points that are generally lower than 200 data points sampled. This fractal analysis shows a possible prediction of end-milling force that has some dynamic chatter property or stationary property in endmilling operation.

• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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• pp.453-460
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• 1997

In order to investigate the electrical conduction properties of polyethylene thin film for power cable with manufacturing methods, the thickness of specimen was the 30, 100[${\mu}{\textrm}{m}$] of LDPE and 200[${\mu}{\textrm}{m}$] of XLPE were manufactured. The experimental condition for conduction properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and the electric field from 1$\times$10$^3$to 5$\times$10$^{6}$ [V/cm]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high electric field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy. At low electric field, the XLPE showed dominant electrical conduction properties by thermal excitation, and transformation of the electron was resisted by the crystal at high electric field.