• 대한수학교육학회지:학교수학
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• 제19권1호
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• pp.77-93
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• 2017

본 연구의 목적은 19명의 중학교 2학년 수학 영재 학생들의 문제 만들기의 특징을 조사하는 것이다. 본 연구에서는 먼저, 선행 연구에서 제안된 분석 틀을 중심으로 영재 학생들의 문제 만들기에서 나타난 확장성과 정교성을 살펴보았다. 다음으로, 영재 학생들이 문제 만들기에서 변경한 조건들을 상세하게 분석하여 영재 학생들의 문제 만들기를 '수평적 문제 만들기'와 '수직적 문제 만들기' 및 하위 범주로 분류하였다. 본 연구의 결과, 중학교 영재 학생들의 수학 문제 만들기는 확장성과 정교성의 측면에서 충분하지 않은 것으로 나타났다. 또한, 영재 학생들은 새로운 문제를 만들 때 원래 문제보다 복잡성이 감소하는 방향으로 문제를 만들며, 원래 문재에 제시된 조건들을 개별적으로는 고려하지만 종합적으로는 고려하지 않는 것으로 나타났다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권1호
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• pp.55-59
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• 2003

With the progress of optical communication technology recently, the development of micro actuator using MEMS technology has been made for optical switching. The actuation types are various; electrostatic, electromagnetic, and electrostatic +electromagnetic etc. Among them, the electrostatic type is the most popular because of the relative ease of fabrication, integration and shielding as well as low power consumption. However, it needs a high voltage to generate a larger driving force. To overcome this problem, we proposed a new type of electrostatic actuator with an extra vertical electrode in addition to the horizontal one. The vertical electrode also lays a role of making the stable angular rotation as a stopper. From the theoretical analysis and experiment, we find the actuation voltage can be reduced up to 50 % of that of the conventional one.

• Journal of the Optical Society of Korea
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• 제5권2호
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• pp.55-59
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• 2001

Results of an experimental study of possible ways to extend the capabilities of a big size transmission type holographic screen are presented. Different approaches to the problem of making a big size screen have been considered and tested experimentally. Up to 60$\times$80 $\textrm{cm}^2$ screens have been recorded on a single photographic plate VRP-M. By attaching a mirror behind the screen, the reflection mode of operation has been obtained. In this arrangement some additional peculiarities appear in the screen, which can be used to extend the screen capabilities. The first possibility is to increase the screen size by mosaicking the subscreens in the reflection mode of operation. Screens of 120$\times$80 $\textrm{cm}^2$ and 180$\times$40 $\textrm{cm}^2$ have been obtained by proper alignment of 60$\times$40 $\textrm{cm}^2$ subscreens. The second possibility is to move the viewing Bone by rotation of the screen together with the mirror and thereby realize by the eye-tracking capability. Methods of increasing vertical size of the viewing zone have been considered. Along with the multi-exposure method, which was considered in previous papers, addition of the vertical diffuser with the optimized scattering angle has been tested experimentally. The vertical size of the viewing zone has been increased by up to 10-15 cm. Another method consists of usage of a diffraction grating with vertical dispersion to solve the same problem.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.47-54
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• 2003

The rotating of rotatory unit with its structural unbalance mass and laundry is making the main vibration problem in a vertical axis washing machine. For reducing vibration problem total washing system hung on the case by its suspension system which is constitute of spring, damper and suspension bar and hydraulic balancer is attached at the upper rim of spin basket. In this paper, we make the dynamic model of washing system of its rigid body motions by 6 degree of freedoms. Hydraulic balancer is modeled by one degree of freedom like auto ball balancer. Elastic motions of washing system have found by method of analytic, experimental and FEM. And we consider first bending mode of each suspension bar and first circumferential mode of assy tub. So, the total washing system is modeled by 12 degree of freedoms. Equations of motion for total washing system have derived, and we perform the dynamic simulation tests.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1035-1043
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• 2021

The shoulder is less stable than other joints, making it easier to onset of various shoulder disorders. In addition, limited range of motion and pain in the shoulder due to shoulder disorders restricts daily life and social activities. The problem with exercise therapy can be reduced in exercise effect by causing boredom through simple repetition of motion, thus reducing the patient's willingness to participate. Therefore, this paper aims to provide a treatment method that can induce active participation of patients by developing devices capable of passive, active, and resistance exercise and serious game contents using them. Furthermore, sEMG was used to verify whether the rotational exercise in the horizontal and vertical using serious game contents helps the shoulder movement actually. The measured sEMG signal was classified as 5 phases according to the angle of rotation and calculated the mean integrated EMG. The mean integrated EMG for the experimental results was higher in all phases when rotational was performed compared to those when both horizontal and vertical rotational exercise remained initial posture, indicating an increase in muscle activity.

• 자원환경지질
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• 제17권3호
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• pp.163-169
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• 1984

암석의 대표적 열원치(熱源値)를 사용하여 지각 열류량(熱流量)의 반전(反轉)을 연구하였으며 2-D 모델은 아주 얇은 정방형판(正方形板)이 고려되었다. 포텐샬 이론을 기초로 하여 지각 열류량과 열원 사이의 새로운 관계를 도출하였으며 두가지 경우의 계산결과가 도시되어 있다. Random search 방법과 ridge regression방법이 비교되었으며 지각열류량의 반전(反轉) 연구에서는 random search 방법의 중요성이 발견되었다.

• 한국해양공학회지
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• 제29권6호
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• pp.427-435
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• 2015

This paper provides the numerical results of a simulation of the flow around a propeller working beneath the free surface. A finite volume method is used to solve the unsteady Reynolds averaged Navier-Stokes (URANS) equations, where the wave-making problem is solved using a volume-of-fluid (VOF) method. The numerical analysis focuses on the propeller wake structure affected by the free surface, where we consider another free surface boundary condition that treats the free surface as a rigid wall surface. The propeller wake under the effect of these two free surface conditions shows a reduction in the magnitude of the longitudinal and vertical flow velocities, and its vortical structures strongly interact with the free surface. The thrust and torque coefficient under the free surface effect decrease about 3.7% and 3.1%, respectively. Finally, the present numerical results show a reasonable agreement with the available experimental data.

• 대한치과보철학회지
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• 제42권2호
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• pp.238-247
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• 2004

Statement of problem: Major objective in making on implant-supported prosthesis is the production of superstructure that exhibits a passive fit when connected to multiple abutments. One requirement to ensure passive fit is to make an accurate impression. Purpose : The purpose of this study was to compare the accuracy of master cast fabricated by using different impression methods at the different impression levels. Material and method: The master model used in this study was resin block having low implant analogs. Impression method studied were 1) direct method on fxiture level (Group FIX-D), 2) indirect method on fixture level(Group FIX-I), 3) modified indirect method on fixture level(Group FIX-M), 4) direct method on abutment level(Group AB-D) and 5) indirect method on abutment level(Group AB-I). Each of the five groups took 10 impressions. Fifty impressions were made for master cast by using Impregum $F^{(R)}$ impression material loaded on individual tray. Three dimensional measuring microscope was used to measure the inter-implant distance. Error rate of each inter-implant distance were calculated and evaluated. Results : The results were as follows. 1. Group FIX exhibited higher accuracy than group AB. 2. In group FIX, modified indirect method showed the highest accuracy, while indirect method showed the lowest accuracy. In group Ab, indirect method showed the higher accuracy than direct method. 3. Group FIX showed larger horizontal error than group AB. But, group AB showed the larger vertical error than group FIX. 4. Group Fix-M showed smallest vertical and horizontal error. Conclusion: An impression method have more effect on accuracy of master model than an impression level. A modified indirect method showed smallest vertical and horizontal error.

• 정보처리학회논문지C
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• 제17C권3호
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• pp.271-280
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• 2010

차세대 이동통신 시스템에서는 3세대 진화망인 LTE(long-Term Evolution), WiMAX/WiBro, 차세대 WLAN등 다양한 무선 접속 기술이 All-IP 기반의 핵심망을 중심으로 통합되는 형태로 발전하고 있다. 이러한 발전에 따라 중첩된 다양한 무선 이종망 환경에서 최적의 조건을 제공하는 망으로의 접속을 제공하는 수직적 핸드오버가 필요하다. 그러나 현재까지는 각각의 네트워크가 독자적 서비스 제공을 위해 독립적인 무선자원관리 기능을 제공하여 왔으므로, 이종망 환경에서의 다양한 네트워크를 끊김없이 서비스를 제공하기 위해서는 개별 네트워크의 무선자원들을 통합적으로 관리하여 최적의 서비스를 제공할 수 있어야 할 것이다. 최근 이러한 무선 이종망 환경에서의 문제점을 해결하기 위해 적응적이동성을 위한 범용링크계층(GLL)과 통합무선자원관리(CRRM) 방식의 개념이 도입되고 있다. 본 논문에서는 LTE와 WLAN 사이에서의 효율적인 수직적 핸드오버를 위한 범용링크계층을 기반으로 정책기반과 다기준 의사결정법(MCDM)을 혼합한 수직적 핸드오버 알고리즘을 제안하고, 퍼지 로직 제어기(FLC)를 이용하여 핸드오버 시점을 적응적으로 결정하는 방안을 제안한다. 시뮬레이션 연구 결과 본 논문에서 제안하는 수직적 핸드오버 기법은 수신신호의 세기를 기반으로하는 방법과 MCDM 만을 사용하는 방법에 비해 데이터 처리량, 핸드오버 성공확률, 서비스 사용비용 그리고 핸드오버 시도 횟수 측면에서 우수한 성능을 보였다.

• 한국운동역학회지
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• 제16권3호
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• pp.173-181
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• 2006

The purpose of this study is grasp the problem of the gymnast, Kim, Dong-Hwa's Kip to Swallow Motion in Rings, and make up for the weak points to help him to perform a better performance. Therefore, two tryouts for $28^{th}$ Athens Olympic Games were filmed using video camera then finalized with Kinematical Analysis using 3D motion analysis program followings are the form of conclusions. 1. In the very first tryout, when he was doing a Swallow Support Scale, his CM position was high and arm slope was deduction because when he was doing Kip, the ascent velocity was low and he tried excessively to pull him on rings due to relying upon angular movement of shoulder joint. 2. When he was doing drop, he let his hip angle bend only little bit and let fall so making shoulder angle wider and maintain the level horizontally occurs strong drop motion when vertical descent is happening. 3. As a result, lowering the direction of a kick makes CM's movement path lower, increase vertical ascent velocity, and it helps to do the Swallow Support motion in short period of time. 4. After a strong drop motion, which is deep and fast, would make rope of ring shake so there is a defect that the body moves to forward area. However, it does not effect in Swallow Support Scale motion. 5. In the second tryout, trunk rotation angle and arm slope was fixed decrease while doing rotary motion. When rotary motion was happening, before the body was going under the rings, maintained his arm slope horizontally so his Swallow Support Scale motion was nearly perfect.