Earticle

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

Rapid Prototyping has made a drastic change in all industries which needs to reduce the time for the development of new products. Orientation and packing in rapid prototyping is considered as the most important factors to maximize the utilization of space in the build chamber and reduce build time. However, the decision of these parameter is mainly dependant on the operators's experience. This paper presents the methodology to find the optimal build layout considering an orientation and packing of multiple parts in SLS processing. Each part is represented as a voxel structure to deal with the inefficiency in a bounding box approach. Test results show that the adapted BL algorithm with a genetic algorithm(GA) can be applicable to a real industry.

본 연구는 한국청소년패널조사 1차 자료를 분석하여 청소년의 비행행동과 공격성간의 쌍방적 관계를 검증하기 위함이다. 즉, 기존의 연구에서 검증된 바 있는 공격성이 비행행동의 예측요인이라는 사실에 더해서 그 반대적인 관계 역시 실증적으로 검증될 수 있음을 밝힌다. 이를 위해 청소년 비행행동 방정식과 공격성 방정식을 하나의 연립방정식 체계로 구성하여 2단계 최소제곱법(two Stage Least-Squares Method: 2SLS)으로 분석하였다. 분석결과 비행행동과 공격성은 서로 쌍방적인 관계를 갖는 것으로 분석되었다. 즉, 공격성이 비행행동을 유발하는 원인이 되기도 하지만 일련의 비행행동을 통한 경험자체 역시 청소년의 공격 성을 증가시키는 요인으로 작용하는 것이다. 이러한 연구는 청소년의 비행행동과 공격성에 대한 기존의 일면적(unilateral relationship)인 분석이 갖는 제한점을 극복하고 쌍방적 관계의 가능성을 제시하고자 한다. 이를 통해 청소년의 비행행동과 공격성과의 관계에 대한 이론적 논의를 더욱 풍부하게 할 수 있는 토대를 마련할 수 있을 것으로 기대한다.

The purpose of this study is to verify the inter-relationship between the delinquent behavior of the adolescents and aggressiveness. To fulfill this purpose, this study used the first data of the National Youth Policy Institute(NYPI) which was collected from middle school students(male: 1,725, female: 1,724). To analyze the inter-relationship between the adolescents' delinquent behavior and aggressiveness, 2SLS(Two Stage Least Square method) assumption method of simultaneous equations was used. By applying this simultaneous equation model, this study found, in addition to the previously verified fact that aggressiveness is the predicting factor for adolescents' delinquent behavior, that the opposite relationship also can be practically verified. That is, aggressiveness and delinquent behavior is not in an unilateral relationship that aggressiveness that aggressiveness has effect on delinquent behavior but is in a bilateral relationship that some part of delinquent behavior increases aggressiveness.

본 연구에서는 우리나라 외환위기 회복 이후기간인 1999년부터 2005년 7개년의 시계열을 갖는 377개 상장기업의 균형패널자료를 이용하여 기업지배구조가 자본구조 와 기업가치에 미치는 영향을 실증적으로 검증하였다. 자본구조방정식을 분석한 실증결과는 첫째, 경영진지분율이 높을수록 위험에 대한 부담이 증가하기 때문에 레버리지비율을 감소시켜 재무위험을 축소시키고자 하는 유 인이 높아지는 것을 알 수 있었다. 둘째, 사외이사비율과 외국인지분율이 높을수록 경 영진에 대한 견제와 감시기능이 강화되어 재무위험이 축소되도록 레버리지비율을 줄 이고자하는 유인이 높아진다는 것을 확인할 수 있었다. 기업가치방정식을 분석한 실증결과는 첫째, 부채비율이 높을수록 부채 사용에 따른 세금절감효과와 재무레버리지효과 등이 기업가치에 긍정적으로 영향을 미치는 것을 확인할 수 있었다. 둘째, 외국인지분율과 국내기관투자가의 지분율이 높아질수록 경영 진의 경영활동을 효율적으로 감시함으로써 경영진의 대리인문제를 감소시켜 기업가치 가 증가된다는 것을 알 수 있었다. 재벌기업과 비재벌기업의 실증결과를 살펴보면 첫째, 자본구조 방정식에서는 재벌 기업은 외국인지분율, 기업규모, 성장성, 유동성이 자본구조에 부(-)의 영향을 미치는 것으로 나타났으며, 비재벌기업은 경영진지분율, 사외이사비율, 외국인지분율, 기업규 모, 수익성, 유동성이 부(-)의 영향을 미치는 것으로 나타났다. 둘째, 기업가치 방정 식에서는 재벌기업은 외국인지분율과 국내기관투자가지분율, 기업규모가 기업가치에 정(+)의 영향을 미치는 것으로 나타났으며, 비재벌기업은 레버리지비율과 경영진지분 율, 외국인지분율, 국내기관투자가지분율, 기업규모, 성장성이 기업가치에 정(+)의 영 향을 미치는 것으로 나타났다.

3D scanners are needed in various fields, and their usage range is greatly expanded. In particular, it is being used to reduce costs at various stages during product development and production. Now, the importance of quality inspection in the manufacturing industry is increasing. Structured optical system applied in this study is suitable for measuring high precision of mold, press work, precision products, etc. and economical and effective 3D scanning system for measuring inspection in manufacturing industry can be implemented. We developed Structured light 3D scanner which can measure high precision by using Digital Light Processing (DLP) projector and camera. In this paper, 3D image scanner based on structured optical system can realize 3D scanning system economically and effectively when measuring inspection in the manufacturing industry.

본 연구는 기업의 기술혁신이 고용과 기업성과에 미치는 영향을 변수 간 양방향 인과관계를 고려하여 분석하였다. 기술혁신의 대리변수는 기업의 특허출원 수이며, 분석대상은 100인 이상 규모의 국내 제조업체이다. 실증분석의 경우 기술혁신(특허출원), 고용(근로자 수, 숙련 근로자 비중), 기업성과(근로자 1인당 매출액)가 종속변수인 연립방정식 모형을 3단계 최소자승추정법(3SLS)으로 추정하였다. 외생변수로 기업의 경영상 특성과 일반적 특성을 통제하였고, 각 방정식의 식별변수로 R&D집약도, 근로자 1인당 노동비용(또는 기업부설연구소 보유 여부), 교육훈련투자를 사용하였다. 분석자료는 인적자본기업패널(HCCP)의 1차년도(2005년)~7차년도(2017년) 자료이며, 이를 NICE신용평가정보(주)의 기업 재무자료 및 한국 특허청의 특허정보와 병합하여 사용하였다. 분석결과에 의하면, 기업의 특허출원이 활발할수록 근로자 수, 숙련 근로자 비중, 근로자 1인당 매출액이 모두 증가하였고, 반대 방향의 인과관계도 모두 유의하였다. 따라서 기업의 기술혁신은 고용의 확대 및 질적 제고뿐 아니라 기업의 지속적인 성장에도 기여하는 것으로 확인된다.

This study analyzes the effects of firms' technology innovation(patent applications) on employment(number of workers and proportion of high-skilled workers) and corporate performance(sales per worker), while considering the two-way causal relationships between these variables. We used the three-stage least squares(3SLS) estimation to examine system of equations in which the dependent variables affect each other with a two-year lag wherever relevant, and applied it to firm-level panel data of Korean manufacturers with 100 or more workers. Our data covered the period of 2005-2017. Exogenous variables, such as firms' managerial and other characteristics, were controlled as explanatory variables. The identification variables for each equation included firms' R&D intensity, labor cost per worker(or operation of firms' own R&D center), and investment on worker training. We find that firms' patent applications increased number of workers, proportion of high-skilled workers, and sales per worker; the causal relationships in the opposite direction were also significant. Evidently, firms' technology innovation is critical to the growth and quality improvement of employment as well as sustainable corporate growth.

Selective Laser Sintering (SLS) is currently recognized as a leading process in the new field of solid freeform fabrication (SFF). It is used to fabricate in a short time any 3 dimensional shapes by layer-by-layer sintering of polymer, ceramic or metal powder. To develop this SFF system, it needs effective laser scanning path, temperature and z-axis control for lamination. Therefore, in this study, through the application of control algorithm for sintering process have performed, temperature evaluation for sintering process has performed and the manufacturing sample using SLS process.

Polymers for laser sintering were needed in order to fabricate the articles with the three-dimensional duplication equipment of SLS (selective laser sintering) process. The thermal properties, particle size, distribution, and shape of polymer powder had a close relation with the processibility of laser sintering. In this study, we prepared new polymer powders with uniform size and higher bulk density by wet process. Wet process consists of several finely-controlled steps such as dissolution, nucleation, propagation and crystallization. Several additives were added to improve the thermal, rheological, and flow properties.

A real object duplication system (RODS), including three dimensional (3D) scanner and solid freeform fabrication system (SFFS), is a device to make three-dimensional objects directly from the drawing or photo data. A Selective Multi-Laser Sintering (SMLS) process designed in this paper is by which computer images received using 3D scanner are built up from polymer powder on building room of large size using dual laser at industrial type SFF system. Using the process can rapidly produce real object duplication components of industrial type such as cylinder, engine block, chassis of automobile, etc. In this paper, the industrial type SFF system using SMLS process is manufactured and the system is satisfied with high precision and high speed processing technique. To research characteristics of each part for theindustrial type SFF system, a structure and thermal analysis and test of each part is carried out. Also, to achievement of high performance for industrial type SFF system, design and fabrication for the structure, heater, nitrogen supply, laser and control part are carried out.

Most of all nano-structures, SiC had a high electrical conductivity and mechanical strengths ay high temperatures. So It was considered a useful materials for nanosized device materials and added materials for strength hardening. Much methods were developed for SiC nanowire and nanorods like CVD, carbothermal reduction, Laser ablation and CNT-confined reduction. These methods used the VLS (Vapor-Liquid-Solid) growth mechanism. In these experiments, SiC nanowire was grown by SLS (Sold-Liquid-Solid) growth mechanism used Graphite substrate, And we characterized its microstructure to compare with VLS growth mechanism.

With Rapid Prototyping system, the efficient packing in a fixed work volume reduces build time when multiple parts are built in a process. In this paper, an efficient and rapid packing algorithm is developed for SLS system that has cylindrical workspace. A genetic algorithm is implemented to place as many part as possible in a vat. For fast computation, a collision detection algorithm "k-DOPs Tree" is implemented.

Selective laser sintering(SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The properties of metal powder are dependent on the heat, it is not easy to do the exact error compensation with analysis and estimation by modeling. This paper suggests that the error is compensated by experimental method and then the accuracy of shape is enhanced by revising of STL file. Also bonding force is measured by an experiment with change of process path.

본 논문에서는 SLA 기반 SLS 매핑 방안을 제안한다. 서비스 품질에 대한 보장를 위해 제시되는 SLA의 구축 시에 SLS는 고려되어야할 사항이며, SLS를 통하여 네트워크 서비스 제공에 대한 품질 파라미터가 결정되는 것이다.

This paper proposes a scheme of SLS mapping on SLA. To consider the service quality for SLA construction SLS should be considered. Through the SLS the quality parameter of network service will be determined.

This Paper Proposes the test pieces of X, Y and Z axes to compensate the shape distortion of Selective Laser Sintering(SLS) parts resulting from the phase change during the sintering process. In no case of the proposed compensation test pieces of X, Y axes the accurate rates of shrinkage can be measured with the reduction of curling which is obtained from adjustment of build orientation and the formula used to get scale factors are proposed with the shrinkage rates of them. The scale factors of X, Y and Z axes are generated by building up proposed compensation test pieces. The generated scale iactors are required to satisfy the dimensional accuracy even if there are changes of the build position and the size of SLS parts in the build chamber. For this reason, it is proposed that the build positions and the size be considered to be noise factors against the compensation test pieces and a method is also proposed that scale factors be selected to robustly maintain the dimensional accuracy of SLS parts under the actual operating conditions with the application of the Taguchi Method.