• Proceedings of the KAIS Fall Conference
• /
• 2001.05a
• /
• pp.241-244
• /
• 2001

스냅핏은 일종의 결속장치로서 흔히 플라스틱 부품들을 서로 체결하는데 이용되는데, 다른 결속장치에 비해 간편하고 생산품의 조립단가를 줄일 수 있고, 또한 분리력은 큰 반면에 결합력은 작게 만들 수 있는 장점을 가지고 있어 널리 사용된다. 스냅핏의 설계는 재료에 따른 물성(property) 및 구조적 강성(stiffness)이 설계 초기단계에서 고려되어야 하고, 또한 사출성형공정에서 스냅핏의 성형성도 예측되어야 한다. 그러나 스냅핏의 형상, 치수, 위치 등을 적절히 설계합성(synthesis)하고 적절한 재료를 선택하는 작업은 공정에 관한 종합적인 지식을 지원해 주는 합리적인 설계도구가 제공되지 못했던 이유로 사출 전문가의 오랜 기간 축적된 경험과 지식에만 전적으로 의존하여 왔다. 본 연구에서는 기존의 전문가에 의존해온 스냅핏 설계방법을 개선하기 위해 사출성형에 의해 제한되어지는 지식을 규칙베이스화하고 재료의 물성과 스냅핏의 형상 및 치수에 파라 스냅핏이 갖는 결합력, 분리력, 변형하중 및 허용언더컷 등을 출력하는 지적 설계 프로그램을 제안하였다.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.9
• /
• pp.839-846
• /
• 2014

Recent trends in the miniaturization and weight reduction of portable electronic parts have driven the use of subminiature screws with a micrometer-scale pitch. As both screw length and pitch decrease in subminiature screws, the resulting clamping force becomes diminishes. In this work, Finite element (FE) analysis is performed to evaluate clamping force of a screw assembly, with a comparison with experimental result. To improve clamping force of subminiature screws, a new screw design is considered by modifying screw thread angle: the thread angle is varied as an asymmetric way unlike the conventional symmetric thread angle. FE analyses are then performed to compare the clamping characteristics of each subminiature screw with different thread angle. The effect of thread angles on the clamping force is then discussed in terms of structural safety for both positive and negative screws.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.06b
• /
• pp.355-360
• /
• 2006

The damping force of a jaw pad is determined by the displacements of main part when two lockers are locked, after the damping angle of a locker was set up in the wedge type rail damp for a container crane. In this time, of the resistance of wedge frame generates due to several factors, the damping angle of a locker to display the initial clamping force will be changed because of the reduction of displacement of extension bar. This resistance is determined by the eccentric distance between the roller and the wedge, and by the gap between the wedge frame and outer frame. In this study we measured the tensile force of both extension bar through the performance test of the prototype rail damp in order to evaluate the effect of the resistance of wedge frame on the damping force of the wedge type rail clamp.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1517-1520
• /
• 2003

In this paper, we design a wedge type rail-clamp which can protect container crane from wind with constant clamping force regardless of the operating period. When we design wedge type rail clamp, it is important to determine the weight for locker to descent smoothly with an initial clamping force of rail and pad. Therefor, this paper suggest a process to decide a wright within proper range which could be obtained using FEA of wedge type rail clamp.

• Information and Communications Magazine
• /
• v.31 no.5
• /
• pp.61-66
• /
• 2014

최근 건강기능식품의 성장으로 농식품 산업이 1차 산업을 넘어 고부가가치 신성장산업으로 재정의되며 각국은 농식품 산업 경쟁력 강화를 위해 ICT 융합을 빠르게 진행하고 있다. 국내 농식품 산업 역시 FTA 체결 등으로 글로벌 경쟁력을 강화하기 위해 국내 발전된 ICT역량을 농식품 산업에 융합하는 노력을 진행하고 있다. 하지만 아직 초기 단계로써 농식품 가치사슬상 생산분야의 시설원예나 축산 생산성 증가를 위한 ICT 융합 단계에 머무르고 있다. 이에 본 논문은 농식품 생산분야 ICT 최신사례로써 노지작물 재배 ICT 융합사례, 수산양식 ICT 융합사례를 소개하고, 농식품 유통 및 판매 분야 ICT 융합사례로써 스마트 가상 스토어, 아마존 대시, 전자가격태그 모델을 소개하고 그 산업적 시사점을 논의하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.2 no.2
• /
• pp.1-5
• /
• 2001

One of the major advantages of using engineering plastics is ease of part assembly through a locking mechanism known as a snap fit. The typical snap fit involves a short cantilever beam with a projection at the free end. which slides over a one way ramp on the mating part to lock in place. The tightness of the mechanism is determined by the lateral interference of the two sliding members If too small they become loose and can't hold together. while if too large. excessive force can be generated. causing failure of the cantilever beam during the assembly operation. Therefore. the accurate determination of the force-deflection relationship for cantilever beams is a key element in snap fit design. And also. the process of injection molding should be considered when cantilever beam is designed. But it is not easy for novice designers to design them appropriately because of the profound knowledge related to injection molding. In this paper. an intelligent design program has been developed and proposed to improve a conventional empirical design method.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.2
• /
• pp.164-173
• /
• 2009

Purpose: The purpose of this study was to evaluate the effect of abutment material on screw-loosening before and after cyclic loading. Among the different materials of abutments, zirconia and metal abutment were used. Material and methods: Two types of implant systems: external butt joint(US II, Osstem Implant, Korea) and internal conical joint(GS II, Osstem Implant, Korea) were used. In each type, specimens were divided into two different kinds of abutments: zirconia and metal(n=5). The implant was rigidly held in a special holding to device ensure fixation. Abutment was connected to 30 Ncm with digital torque gauge, and was retightened in 30 Ncm after 10 minutes. The initial removal torque values were measured. The same specimens were tightened in 30 Ncm again and held in the cycling loading simulator(Instron, USA) according to ISO/FPIS 1480. Cycling loading tests were performed at loads 10 to 250 N, for 1 million cycles, at 14 Hz,(by subjecting sinusoidal wave from 10 to 250 N at a frequency of 14 Hz for 1 million cycles,) and then postload removal torque values were evaluated. Results: 1. In all samples, the removal values of abutment screw were lower than tightening torque values(30 Ncm), but the phenomenon of the screw loosening was not observed. 2. In both of the implant systems, initial and postload removal torque of zirconia abutment were significantly higher than those of metal abutment(P<.05). 3. In both of the implant systems, the difference in removal torque ratio between zirconia abutment and metal abutment was not significant(P>.05). 4. In metal abutments, the removal torque ratio of GS II system(internal conical joint system) was lower than that of US II system(external butt joint system)(P<.05). 5. In zirconia abutments, the difference in removal torque ratio between the two implant systems was not significant(P>.05). Conclusion: Zirconia abutment had a good screw joint stability in the condition of one million cycling loading.

• The Korean Journal of Air & Space Law and Policy
• /
• v.26 no.1
• /
• pp.65-92
• /
• 2011

Die soeben entwickelten Grundgs$\ddot{a}$tze k$\ddot{o}$nnen dazu f$\ddot{u}$hren, dass es bei Fluggesellschaften zum Abschluss mehrerer Tarifvertr$\ddot{a}$ge $\ddot{u}$ber Personalvertretungen durch verschidene Gewerkschften kommt. Dies leitet schlie${\ss}$lich zu der bereits angesprochenen Problematik der Tarifkonkurrenz $\ddot{u}$ber. Tarifkonkurrenz zeichnet sich bekanntlich dadurch aus, dass f$\ddot{u}$r dasselbe Rechtsverh$\ddot{a}$ltnis dieselbe Regelungsmaterie durch mehr als einen Tarifvertrag geregelt wird. Eine solche Tarifkonkurenz kann unabh$\ddot{a}$ngig von der Frage, ob Regelungsgegenstand betriebsverfassungsrechtlicher Normen ein betriebliches Rechtsverh$\ddot{a}$ltnis ist, auch bei dieser Art von Tarifnormen auftreten. Dabei betriebsverfassungsrechtlichen Kollektivnormen gem$\ddot{a}{\ss}$ $\S$3 Abs. 2 TVG die Tarifbindung des Arbeitgebers f$\ddot{u}$r die Anwendungsbarkeit gen$\ddot{u}$gt, wird beim Vorhandensein mehrerer solcher Tarifvertr$\ddot{a}$ge h$\ddot{a}$ufig pauschal von einer in jedem Fall aufzul$\ddot{o}$senden tarifkonkurrenz gesprochen. $\ddot{U}$berschneiden sich die Geltungsbereiche mehrerer Tarifvertr$\ddot{a}$ge $\ddot{u}$ber personalvertretungsrechtliche Fragen der im Luftbetrieb t$\ddot{a}$tigen Besch$\ddot{a}$ftigten und handelt es sich nicht um textidentische Regelungen, f$\ddot{u}$hrt indes kein Weg daran vorbei, dass eine Tarifkonkurenz besteht, die einer Aufl$\ddot{o}$sung bedarf. Die Rechtsprechung hat sich zur speziellen Fragen der Aufl$\ddot{o}$sung einer Konkurrenz betriebsverfassungsrechtlicher Tarifnormen soweit ersichtlich noch nicht ge$\ddot{a}$u${\ss}$ert. Nicht zuletzt aus diesem Grund wird in der Literatur ein buntes Spektrum an L$\ddot{o}$sungen pr$\ddot{a}$sentiert, wobei sich die meisten neueren Stellungnahmen vor allem mit Organisationstarifvertr$\ddot{a}$gen im Sinne von ${\S}$3 BetrVG besch$\ddot{a}$ftigen.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.2
• /
• pp.137-147
• /
• 2008

Statement of problem: Dental implant procedure has been recognized as a very effective treatment to rehabilitate fully or partially edentulous patients. However, mechanical failures such as screw loosening, screw fracture have been still reported frequently. Purpose: The purpose of this study was to evaluate the influence of tungsten carbide/carbon coating, which has superior hardness and frictional wear resistance, on implant-abutment screw loosening of three different joint connections after one million cyclic loading. Material and methods: The values of detorque before and after loading were measured in three different joint connections (Osstem Implant, Korea), one external butt joint, US II implant system and two internal cones, SS II and GS II system. The values of detorque before loading was analyzed by one-way ANOVA, and two-way ANOVA and Scheffe' test were performed for the value of detorque after loading. Results: 1. The values of initial detorque of tungsten carbide/carbon coated Ti alloy screw were smaller those of Ti alloy screw (P<.01), and there were no differences among implant systems in each screw (P>.05). 2. In comparison of loss rate of detorque value after cyclic loading, US II system was greater than SS II and GS II system but there was no difference between SS II and GS II system (P<.01). 3. Loss rates of detorque value after cyclic loading decreased consistently at tungsten carbide/carbon coated Ti alloy screw comparing with Ti alloy screw in all implant systems (P<.01), and there were no differences among three systems in reduction of loss rates by using tungsten carbide/carbon coated Ti alloy screw (P>.05). Conclusion: Tungsten carbide/carbon coating to increase preload with reduction of friction resistance was a effective way to decrease screw loosening by functional loading.

• Journal of Korea Port Economic Association
• /
• v.34 no.4
• /
• pp.191-208
• /
• 2018

This paper focuses on the integration aspect of operators to determine an improvement strategy for the operating system to enhance competitiveness of Busan Port. This Study proposes the following alternatives: valuation standards for the integration of operators, the road map for the integration period, the scope and role setting of integrated operators' participation of Busan Port Authority(BPA), and the separation and linkage North Port and the New Port operators. First, the valuation standards for operator integration should be based on international standards. Additionally quantitative factors such as financial situation, business performance and participating companies' profitability, and the qualitative factors such as management ability, technology, and labor relations should be considered. Second, the timing of North Port's operator integration should be prioritized in the short term in conjunction with the commencement of its phase 2-4, 2-5, and 2-6. The integration of New Port operators should provide a road map for a relatively long-term perspective. Third, the participation of BPA' integrated operators should be considered in terms of publicity as a policy coordinator between terminals and by pursuing the profitability of entering into overseas business by fostering Korean global terminal operators. The scope and role of participation ensures that the experience and technology of the terminal operation business is maximized. Fourth, because physically intergrating the North Port' operator into a single corporate form is difficult, initially establishing a special purpose company to maximize the effect of the integrated operation is necessary. Then, the operators decided to convert to a holding company given the termination of the lease term contract with the State or BPA, and ultimately proposed a merger into a single corporation.