• 마케팅과학연구
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• 제18권2호
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• pp.1-18
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• 2008

The objective of this paper is to describe the construct of bullwhip effect beyond supply chains, namely at industrial and societal levels. The author provides a conceptual discussion of the bullwhip effect - its derivation is extended, and the positioning of the construct is broadened. The bullwhip effect has been explored within intra-organisational and inter-organisational supply chains. A broader descriptive framework is introduced, one that positions the bullwhip effect construct at industrial and societal levels. A conceptual framework is provided that bridges the interface between the micro and macro environments of the bullwhip effect construct, but further conceptualization is required. The introduced derivation and positioning of the bullwhip effect construct reveal a number of research potentials. A principal one is that the exploration of the construct may consider the industrial and/or the societal environment when the bullwhip effect is studied in supply chains. The extended derivation and broadened positioning of the bullwhip effect in the overall environment is of interest to practitioners. It stresses the importance of contextual factors in operative, tactical and strategic supply chain performance. The principal contributions are: a) an interface between micro and macro levels in supply chain performance contributing to an extended derivation of the bullwhip effect; b) a typology of the bullwhip effect contributing to broadening the positioning of the same construct; c) the bullwhip effect being seen as two-way view construct at the micro level and d) a framework ofmanagerial implications. Most important of all is that the causes and effects of the bullwhip effect have been addressed in a wider context that so far has been underestimated in literature.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.316-321
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• 2004

In this paper, we have developed a new mounting head system for flip chip. The proposed head system consists of a macro/micro positioning actuator for stable force control. The macro actuator provides the system with a gross motion while the micro device yields fine tuned motion to reduce the harmful impact force that occurs between very small sized electronic parts and the surface of a PCB(printed circuit board). In order to show the effectiveness of the proposed macro/micro chip mounting system, we compared the proposed system with the conventional chip mounting head equipped with a macro actuator only. A series of experiments were executed under the mounting conditions such as various access velocities and PCB stiffness. As a result of this study, a satisfactory voice coil actuator as the micro actuator has been developed, and its performance meet well the specifications desired for the design of the chip mounting head system and show good correspondence between theoretical analysis and experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1060-1065
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• 2003

This paper contributes to development of a new chip mounting head system for flip chip. Recently, the LDM(Linear DC Motor) has been widely used, because it has particular merits than the rotary type motors. In this paper, we proposed a macro/micro positioning system for force control of a chip mounting system. In the proposed macro/micro system, the macro actuator provide the system with a gross motion while the micro device yields fine tuned motion to reduce the harmful impact force that occurs between very small sized electronic parts and PCB surface. In order to prove the effectiveness of the proposed macro/micro chip mounting system, we compared the proposed chip mounting head with the conventional chip mounting head equipped with a macro actuator only. A series of experiments were executed under the mounting conditions of various access velocities and PCB stiffness. As a result of this study, a satisfactory voice coil actuator as the micro actuator has been developed, and its performance meet well the specifications desired for the design of the chip mounting head system and show good correspondence between theoretical analysis and experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.332-336
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• 2004

To position precision machines accurately, linear motion (LM) guides having rolling elements can be used. For ultra-accurate positioning control of the precision machines, the understanding of the dynamic behavior of the LM guide at the macro and/or micro scales is most critical, but the research on this subject is rare. The objective of the present research is to observe the vibration phenomena of the LM guide. Bails are used as the rolling elements in this work. Several experiments show the nonlinear characteristics of the LM guide such as hysteresis behavior and force-dependent natural frequencies phenomena.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.1029-1034
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• 2004

Linear motion ( LM) guides having rolling elements have been used to position precision machines accurately. For ultra-accurate Positioning control of Precision machines, the understanding of the dynamic behavior of the LM guide at the macro and/or micro scales is most critical, but the research on this subject is rare. The objective of the present research is to investigate the vibration phenomena of the LM guide where balls are used as the rolling elements. Several experiments show the nonlinear characteristics of the LM guide such as hysteresis behavior and force-dependent natural frequencies phenomena.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.371-375
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• 2001

The concept of a new linear motor that uses piezo-stack actuator is demonstrated. The working principle is far different from the conventional inchworm motor. This motor is based on the self-moving cell concept. The linear motor has three cells and each cell is constructed with one piezo-stack actuator and a shell structure. A cell train is constructed by connecting these cells and the cell train is fitted into a guide way with a proper interference. The cell train moves along the guide way, by activating each cell in succession. The moving motion of the motor is tested. Since this linear motor uses piezo-stack actuator with unified clamping cell, it can produce fast speed, high resolution and large push force.

• 한국과학교육학회지
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• 제41권2호
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• pp.115-131
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• 2021

전 지구적으로 기후변화 위기 상황이 고조되고 있는 오늘날 사회적 행동을 통해 사회를 변화시킬 수 있는 '기후변화를 주제로 한 사회적 실천지향 SSI 교육'의 필요성이 증가하고 있다. 본 연구는 사회문화적 관점을 바탕으로, 기후변화를 주제로 한 사회적 실천지향 SSI 수업을 실행하는 과정에서 직면하는 교사의 어려움이 무엇인지 탐색하고자 하였다. 이를 위해 46차시 동안 진행된 수업에 대한 질적 단일 사례연구를 진행하였으며, 연구 참여자와의 심층 면담, 교사 성찰일지, 수업 동영상, 학생 면담, 학습 결과물, 참여 관찰일지 등과 같은 질적 자료를 수집하였다. 수집된 자료는 실천적-평가적 차원의 구조를 micro(교실), meso (학교), macro (한국 사회) 장으로 나누어 분석하였다. 연구 결과 micro 장에서 새로운 시도의 수업으로 인해 기후변화에 대한 학생들의 이해나 인식을 파악하기 힘들었으며 특히 학생들이 기후변화를 나의 문제라고 인식하는 주인의식을 가지는 데 어려움이 있어 교사가 원하는 방향으로 수업이 이루어지지 않았다. 또한, 학생들은 스스로를 어린이로 위치 지으며 계획한 사회적 행동의 실현 가능성에 대해 회의적이거나, 사회적 행동을 이해하지 못하고 그 가치에 대해 공감하는 데 어려움을 겪어 학습 목표를 성취시키는 데 어려움이 있었다. meso 장에서는 동학년 교사와 교육과정을 비슷하게 운영해야 하는 학교 문화 속에서 교사만의 교육과정을 운영하는 데 어려움을 겪었다. 또한, 기후변화 수업이라는 낯선 과학 수업 주제에 대한 부담을 드러내는 동료 교사들과 소통이 단절된 채 교육과정을 홀로 운영하는 과정에서 전문성을 키워나가는 데 어려움을 겪었다. 관리자 역시 사회적 행동에 대한 소극적인 지원을 하여 학교 밖으로 사회적 행동을 실행하는 과정에서 갈등 상황에 직면하였다. 마지막으로 macro 장에서는 본 수업의 교수학습을 지원하는 물적 자원이 미흡하였으며, 학생들의 사회적 행동에 대한 사회구성원들의 제한된 시각이 교수학습상황의 거시적 제약조건으로 작용하고 있었다. 분석을 위해 유목화된 각 장의 제약조건들은 실제로는 독립적이고 분절적인 요소가 아닌 상호 간에 영향을 미치며 복합적인 그물망을 형성하며 구조적 제약조건을 형성하고 있었다. 이에 본 연구 결과를 통해 기후변화를 주제로 한 사회적 실천지향 SSI 수업을 실행하는데 교육 공동체 여러 주체의 다층적인 지원과 노력이 필요함을 시사한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3858-3874
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• 2021

As an essential part of the urban transportation system, precise perception of the traffic flow parameters at the traffic signal intersection ensures traffic safety and fully improves the intersection's capacity. Traditional detection methods of road traffic flow parameter can be divided into the micro and the macro. The microscopic detection methods include geomagnetic induction coil technology, aerial detection technology based on the unmanned aerial vehicles (UAV) and camera video detection technology based on the fixed scene. The macroscopic detection methods include floating car data analysis technology. All the above methods have their advantages and disadvantages. Recently, indoor location methods based on wireless signals have attracted wide attention due to their applicability and low cost. This paper extends the wireless signal indoor location method to the outdoor intersection scene for traffic flow parameter estimation. In this paper, the detection scene is constructed at the intersection based on the received signal strength indication (RSSI) ranging technology extracted from the wireless signal. We extracted the RSSI data from the wireless signals sent to the road side unit (RSU) by the vehicle nodes, calibrated the RSSI ranging model, and finally obtained the traffic flow parameters of the intersection entrance road. We measured the average speed of traffic flow through multiple simulation experiments, the trajectory of traffic flow, and the spatiotemporal map at a single intersection inlet. Finally, we obtained the queue length of the inlet lane at the intersection. The simulation results of the experiment show that the RSSI ranging positioning method based on wireless signals can accurately estimate the traffic flow parameters at the intersection, which also provides a foundation for accurately estimating the traffic flow state in the future era of the Internet of Vehicles.