• Journal of Computational Design and Engineering
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• 제3권2호
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• pp.140-150
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• 2016

Normally all manufacturing and fabrication processes introduce residual stresses in a component. These stresses exist even after all service or external loads have been removed. Residual stresses have been studied elaborately in the past and even in depth research have been done to determine their magnitude and distribution during different manufacturing processes. But very few works have dealt with the study of residual stresses formation during the casting process. Even though these stresses are less in magnitude, they still result in crack formation and subsequent failure in later phases of the component usage. In this work, the residual stresses developed in a shifter during casting process are first determined by finite element analysis using ANSYS(R) Mechanical APDL, Release 12.0 software. Initially the analysis was done on a simple block to determine the optimum element size and boundary conditions. With these values, the actual shifter component was analyzed. All these simulations are done in an uncoupled thermal and structural environment. The results showed the areas of maximum residual stress. This was followed by the geometrical optimization of the cast part for minimum residual stresses. The resulting shape gave lesser and more evenly distributed residual stresses. Crack compliance method was used to experimentally determine the residual stresses in the modified cast part. The results obtained from the measurements are verified by finite element analysis findings.

• 정보과학회 논문지
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• 제44권2호
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• pp.213-222
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• 2017

최근 IoT 기술의 확산으로 인해 산업 무선 센서 네트워크 분야에서도 IoT 기술이 적용되고 있다. 특히 스마트 팩토리는 유연한 공정 변화 및 맞춤형 제조를 위해 제조 설비에 무선 통신 및 네트워크 기술을 적용하는 것으로 무선 노드의 이동과 빈번한 네트워크 변동에도 적응적으로 네트워킹을 지원하는 것이 중요하다. 대표적인 산업 무선 센서 네트워크 기술인 IEEE 802.15.4e는 TSCH와 DSME의 2가지 MAC 모드를 사용하고 있으며, 그 중 DSME는 네트워크 변동에 강한 저 지연 실시간 전송을 위한 기능을 제공하고 있다. 본 논문에서는 DSME에 기반한 분산 스케줄링 기법을 제안한 것으로 이동성이 높은 산업 무선 센서 네트워크에서 트래픽에 적응적으로 통신 슬롯을 할당하여 산업 무선 센서 네트워크의 시의성과 전송 신뢰성을 확보하고 있다. 제안 알고리즘은 Coordinator 노드의 Local queue의 길이와 Global queue의 길이를 비교하며, Slot stealing 기법에 기반한 Traffic-aware 분산 스케줄링을 수행한다. Slot stealing 기법을 통해 개별 통신 노드의 전송 기회를 효율적으로 보장하면서, Slot stealing을 통해 야기되는 충돌로 인한 성능 저하 및 재전송 문제를 극복하기 위해 GroupACK 기법 적용 및 CAP 구간에 재전송 예약 슬롯을 할당하였다. 이 논문에서는 제안 알고리즘을 TSCH, DSME, legacy IEEE 802.15.4 slotted CSMA/CA와 비교하였고, 다양한 이동성 실험에서 성능 우위를 확인하였다. 실험을 통해 30개 이상의 노드로 구성된 토폴로지에서는 전송 대역폭이 15% 이상 개선됨을 확인하였다. 또한, slotted CSMA/CA에 비해서는 약 40%, TSCH 및 DSME 표준기법에 비해서는 제안 알고리즘을 탑재한 DSME가 15%의 전력 소모 절감이 나타나는 것을 실험적으로 확인하였다.

• 디지털융복합연구
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• 제14권5호
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• pp.237-245
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• 2016

최근 급격한 경영환경 변화로 인해 근로자들의 고용불안감이 커짐에 따라 모든 근로자들이 느끼는 직무에 대한 심리적인 불안정성은 더욱 증가하고 있는 추세에 있다. 따라서 본 연구에서는 직무불안정성과 조직시민행동간 자기효능감의 조절효과에 대하여 살펴보았다. 대상은 대전시, 세종시, 충청남 북도 소재 중소 제조업의 종업원들을 대상으로 하였으며, 2015년 8월 5일부터 동년 동월 30일까지 총 500부를 배포하여 321부가 회수되어 응답률이 64.2%였다. 회수된 설문지 중 응답이 불성실한 설문지 9부를 제외한 312부를 분석에 이용하였다. 연구결과는 다음과 같다. 첫째, 직무불안정성이 조직시민행동에 부(-)의 영향을 미치는 것으로 나타났다. 둘째, 고용불안정성과 조직시민 행동과의 관계에서 자기효능감이 조절효과가 있는 것으로 나타났다. 따라서 직무불안정성의 위협 속에서도 종업원의 자기효능감이 높으면 조직시민행동을 높일 수 있음을 의미한다. 결과적으로, 기업의 생존과 직무가 불안정한 현 상황에서 중소제조업의 경영자는 우선 종업원들에 대한 교육과 내적 보상 등을 통해 자기효능감을 높일 필요가 있다는 것을 시사한다고 할 수 있다. 연구의 한계점은 연구대상이 대전시, 세종시와 중청남 북도지역의 중소기업의 구성원들을 주된 연구표본으로 삼고 있다는 점이다. 따라서 상황적 특이성이 관찰 될 수 있기 때문에 향후에는 보다 다양한 지역, 다양한 업무 및 산업으로 확장된 연구가 필요할 것이다.

• Asia pacific journal of information systems
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• 제17권2호
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• pp.1-28
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• 2007

The success of new product development is a key factor for getting competitive advantages. Marketing research has been investigating marketing capability, manufacturing technical capability, cross-functional integration, market knowledge competence, market orientation, and competitive environment as the key success factors of new product development. Recently, the role of IT infrastructure in enhancing new product advantage is assumed in the literature. However, the empirical studies on the role of IT infrastructure are lacking. The purpose of this study is to empirically exam the impacts of IT infrastructure on new product competitive advantage. In this study, IT infrastructure is conceptualized as the flexibility of IT infrastructure. Based on previous research, a conceptual model is established by incorporating the direct impact of IT infrastructure flexibility and its indirect impact through the key success factors on new product development. To empirically test the research model, data are surveyed from a pair of IS department and Marketing department of 92 consumer goods manufacturers. By employing PLS technique, the measurement reliability and reliability of research variables are tested and the path analysis is conducted to do the hypothesis testing. The path analysis shows that IT infrastructure flexibility has no direct effect on new product advantage, However, the indirect effect of IT infrastructure is found, which is mediated by marketing capability, manufacturing technical capability, cross-functional integration, and market orientation respectively. Hence, The flexible IT infrastructure increases cross-functional integration (H1), market orientation (H3), marketing capability (H5), and manufacturing technical capability (H6). All success factors of new product development excepts for competitive environment have a positive association with new product competitive advantages (from H10 to H14). Finally, the path from IT infrastructure flexibility to cross-functional integration, to market orientation, to market knowledge capability, and to new product advantage is found as the strongest path. These results indicate that the flexible IT infrastructure enhances information sharing with multiple departments and collaboration within a distributed innovation environment. The collaboration among departments positively affects the level of customer and competitor intelligence. The ability to obtain knowledge about customers and competitors makes firms to adapt to a changing environment quickly and to respond to customers' demands adequately. The flexible IT infrastructure also enhances the capability of organization to more rapidly respond to the changes in product design resulting in faster product development and reduced costs. In addition to, it enhances marketing capability by the two-way communications with customers and the analyses of various kinds of customer data. In brief, the finding of this study suggests that the flexible IT infrastructure allows many firms to pursue sustained new product competitive advantages. This study advances research on IT infrastructure in two important aspects. First, by Integrating marketing research and IS research, this study develops a conceptual model on the role of IT infrastructure in enhancing new product advantage. Second, it empirically finds the indirect impacts of IT infrastructure on new product advantage, which confirms the potential for the IS field to contribute to new product development research. The limitations of this study are also discussed to provide research directions for future research.

• 한국산학기술학회논문지
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• 제15권10호
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• pp.6193-6203
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• 2014

본 연구는 50인 미만의 제조업 근로자들의 수면의 질을 평가하고, 이들의 인구사회학적 특성, 건강행태 및 직업관련 특성과 수면의 질과의 관련성을 규명하고자 대전광역시 D공단에 소재하고 있는 50인 미만의 소규모 제조업 사업장 남성 근로자 856명을 대상으로 2011년 4월 1일부터 6월 30일까지의 기간 동안에 자기기입식 설문조사를 실시하였다, 조사내용은 조사대상의 인구사회학적 특성, 건강관련행위 특성, 직업관련 특성 및 한국판 PSQI를 사용한 수면의 질 평가 등이었다. 연구 결과, PSQI에 의한 수면의 질 평가에서 전체 조사대상자의 32.0%는 수면의 질이 좋은 것으로, 68.0%는 수면의 질이 좋지 않은 것으로 평가되었다. 위계적 다중회귀분석 모델에 의한 조사대상자의 수면의 질(PSQI) 수준은 기혼군일수록, BMI가 낮을수록, 주관적인 건강상태가 좋지 않을수록, 비흡연군, 음주군, 규칙적인 운동을 하지 않는 군 및 커피를 음용하는 군, 생산직 근로자, 주당 근무시간이 길수록, 질병으로 인한 결근 경험이 있는 군일수록, 외래진료경험이 있는 군일수록 유의하게 낮았다. 위의 모델에서 보면 직업관련 특성이 추가됨으로 해서 13.1%의 설명력을 증가시켜 PSQI에 의한 수면의 질에 직업관련 특성이 높은 관련성이 있음을 시사하고 있다.

• 한국정밀공학회지
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• 제30권1호
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• pp.11-17
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• 2013

'Multi-scale mass-deployable cooperative robots' is a next generation robotics paradigm where a large number of robots that vary in size cooperate in a hierarchical fashion to collect information in various environments. While this paradigm can exhibit the effective solution for exploration of the wide area consisting of various types of terrain, its technical maturity is still in its infant state and many technical hurdles should be resolved to realize this paradigm. In this paper, we propose to develop new design and manufacturing methodologies for the multi-scale mass-deployable cooperative robots. In doing so, we present various fundamental technologies in four different research fields. (1) Adaptable design methods consist of compliant mechanisms and hierarchical structures which provide robots with a unified way to overcome various and irregular terrains. (2) Soft composite materials realize the compliancy in these structures. (3) Multi-scale integrative manufacturing techniques are convergence of traditional methods for producing various sized robots assembled by such materials. Finally, (4) the control and communication techniques for the massive swarm robot systems enable multiple functionally simple robots to accomplish the complex job by effective job distribution.

• 복식
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• 제64권2호
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• pp.84-97
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• 2014

This research aimed to explore strategies to develop the cashmere industry in Mongolia. Questionnaire consisted of questions regarding the necessity of development in different sectors in the cashmere industry, and areas of necessary competition for the development of Mongolian cashmere industry. In addition, characteristics of respondents and their companies were questioned. Surveys were distributed to people working in cashmere manufacturing companies in Ulaanbaator, Mongolia between July 25th, 2012 to September 3rd, 2012, and a total of 79 questionnaires were included in the final analysis using descriptive analysis, t-test, one-way ANOVA, and Duncan test. Results showed that respondents perceived design as the sector that needed the most improvement, and product related strategies such as product quality, product differentiation, and design were more important than distribution or promotion related strategies. The perceptions on the development strategies differed according to company size and their target markets (domestic vs. export). Overall, respondents working in smaller companies showed greater concern for most sectors, and also felt technology, product quality and design were more important than those in working in larger companies. Companies that targeted the domestic market showed greater concern for herding and scouring sector than companies that exported, while the latter evaluated government policy, network, distribution/export channels more importantly than the former in developing the Mongolian cashmere industry.

• Structural Engineering and Mechanics
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• 제55권3호
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• pp.461-472
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• 2015

The existence of initial imperfections in manufacturing or assembly of double-layer space structures having hundreds or thousands of members is inevitable. Many of the imperfections, such as the initial curvature of the members and residual stresses in members, are all random in nature. In this paper, the probabilistic effect of initial curvature imperfections in the load bearing capacity of double-layer grid space structures with different types of supports have been investigated. First, for the initial curvature imperfection of each member, a random number is generated from a gamma distribution. Then, by employing the same probabilistic model, the imperfections are randomly distributed amongst the members of the structure. Afterwards, the collapse behavior and the ultimate bearing capacity of the structure are determined by using nonlinear push down analysis and this procedure is frequently repeated. Ultimately, based on the maximum values of bearing capacity acquired from the analysis of different samples, structure's reliability is obtained by using Monte Carlo simulation method. The results show the sensitivity of the collapse behavior of double-layer grid space structures to the random distribution of initial imperfections and supports type.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1326-1331
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• 2005

A product is designed through the collaboration among engineers in several fields such as design, analysis, and manufacturing. These series of functions are performed repeatedly during the design process. An easy access and exchange of the model data is one of the important elements that help to shorten production development time. Especially, the importance of data exchange between CAD and CAE applications is increasing in the field of verification and estimation of the products. However, information and knowledge of model which is generated by a CAD software cannot be transferred by a function of CAE software, as an exchange of product data between CAD and CAE applications. It causes a delay in design analysis and eventually discourages a designer's effort in improving his design. Therefore, we need to integrate a commercial CAD and CAE applications effectively and to use the same interface on a product model obtained in a distributed environment. This paper shows how to implement a model exchange between CAD and CAE by a web-service and how to provide a communication environment among engineers.

• Journal of Welding and Joining
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• 제23권1호
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• pp.41-47
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• 2005

Arc pressure is one of important factors in understanding physical arc phenomena. Especially it affects on the penetration, size and shape of TIG welding. Some researches were reported on the effect of arc pressure in low and middle current region. But there are not any research in high current region. The purpose of this study is to investigate the arc pressure distribution with mixing ratio of shield gas such as Ar and He gases. A Cu block with water cooling was specifically designed and used as an anode electrode in order to measure the arc pressure in high current region. Then, the arc pressure distribution was measured with change in welding current and mixing ratio of shield gases. The arc force was obtained by numerically integrating the measured results. As the results, it was shown that the arc pressure was concentrated at the central part of the arc in middle and high current regions when a pure Ar gas was used. In case of Ar + He mixing gas, the arc pressure was much lower than that of pure Ar gas. In addition, it was widely distributed to radial direction.