• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1114-1116
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• 2002

The characteristics of voltage drop and THD for parallel operating 11 PCRs (Phase Controlled Rectifiers) are analysed. The PCRs are used to drive high current (1.6 kA ${\sim}$ 3.7 kADC) electromagnetic coils for electromagnets. All the PCRs operate simultaneously in pulsed mode, and the pulse shot occurs every 150 seconds. During the pulse operation the PCR output current ramps up for 4 seconds, and then keeps flat top state for 2 seconds, and finally ramps down for 4 seconds. For the flat top mode a severe voltage drop and distortion appear in the power system because transformers for the PCRs are designed considering pulsed mode operation. It is expected that the analysis method can be applied to improve the system performance including power factor and design of high power pulsed mode operating power supply systems.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.653-655
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• 2013

본 논문은 안드로이드 기반 셋톱박스에서 다중 USB 저장 장치 연결에 관한 연구이다. 안드로이드 OS의 경우 모바일 OS의 특성상 MicroSD 카드와 같은 단일 종류의 저장매체만을 사용가능하도록 구현되어, 미디어재생, 녹화와 같은 셋톱박스의 기능 포함하기에 제한적인 단점이 있다. 본 논문은 이러한 제한적인 부분의 개선을 위한 안드로이드 OS 내 다중 볼륨 매니지먼트 시스템 구현을 통해 외장 디스크 드라이브, 외장 USB 메모리와 같은 외부 저장 매체의 다중 인식 방안에 대한 연구이다.

• 한국운동역학회지
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• 제18권1호
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• pp.11-19
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• 2008

전국 규모의 경기에서 우승한 선수들을 포함한 남자대학 선수 8명을 대상으로 했다. 피험자의 4명은 펜홀더 그립, 4명은 세이크핸드 그립의 라켓을 사용하며 모두 오른손을 사용했다. 탁구의 포핸드 드라이브와 스매시의 라켓스윙동작과 관련된 각도성분, 스윙궤도, 스윙자세 등의 3차원 각운동 특성을 비교 분석한 결과 다음과 같은 결론을 얻었다. 라켓각(p<.05)과 라켓의 스윙각(p<.01)에서 두 동작 간 유의한 차이를 보였다. 스매시는 백스윙 자세에서 이미 라켓을 세워 라켓각을 크게 유지했으며, 라켓의 스윙각을 작게 해서 볼 스피드에 비중을 두는 것을 알 수 있었다. 또한 백스윙 자세에서 라켓헤드의 높이도 두 동작 간 큰 차이가 나타났다. 임팩트 순간 phg에서 두 동작 간 라켓 장축의 열림각의 차이가 크게 나타난 것을 보면, 볼에 순회전의 스핀을 넣기 위해서 약간 뒤에서 임팩트가 이루어진 것을 알 수 있었다. 백스윙 자세에서 상체의 기울기는 드라이브 동작에서 phg보다 shg에서 상체를 조금 더 구부리는 것은 중립 자세에서 라켓 그립의 구조적 차이로 인한 것으로 판단된다.

• 한국운동역학회지
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• 제26권3호
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• pp.265-272
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• 2016

Objective: The aim of this study was to analyze X-factor, triple X-factor, and the center of pressure (COP) according to the feel of golf driver swing. Method: For this research, 9 golfers from the Korea Professional Golfers' Association (age: $30.11{\pm}2.98yrs$, height: $178.00{\pm}8.42cm$, weight: $76.22{\pm}8.42kg$, experience: $10.06{\pm}3.11yrs$) were recruited to participate in the experiment. Twelve Motion Analysis Eagle-4 cameras were installed and an image analysis was conducted by using the NLT (non-linear transformation) method, and 2 units of Kistler type 5233A dynamometer were used to measure ground reaction force. The sampling ratio was set at 1000 Hz. The golfers each took 10 swings by using their own driver, and chose the best and worse feel from among 10 shots. A paired-sample t-test was used to analyze the results. Results: In regard to feel, no change in head speed, X-factor, and the triple X-factor's X-factor stretch, hip rise, and head swivel, was observed (p>.05). Regarding ground reaction force, a difference was observed between the top of the backswing (p<.05) and impact (p<.05) in the vertical force of the left foot. For COP, a difference was also observed between the mid backswing (p<.001), late backswing (p<.001), and top of the backswing (p<.05) for the right foot X-axis and Y-axis mid follow through (p<.01). Conclusion: It can be reasoned that, irrespective of feel, the head speed, X-factor and triple X-factor's X-factor stretch, hip rise and head swivel did not have an effect on drive distance for domestic golfers, and the vertical reaction force of the left foot and left-right movement span's pressure dispersal of the right foot had an increasing effect on drive distance.

• 한국산업융합학회 논문집
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• 제23권2_2호
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• pp.233-244
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• 2020

A double-parked car is the one that is parked in a crowded parking lot with its transmission gear in neutral position and its auxiliary brake released. A double-parked car can be moved by pushing it but doing so is very difficult and dangerous. In a previous study, we proposed an omni-directional mobile robot for moving a double parked car. In that study we adopted Mecanum wheels. Even though the proposed robot showed successful results, it has some drawbacks such as dependency on a load condition, complexity in control, inefficiency in power use, etc. To overcome those drawbacks, we propose a differential drive robot with ordinary two tire wheels. The proposed robot consists of two parts, one is a wheel part and the other is a body part. By selectively connecting or disconnecting those two parts with the aid of an electric brake, the proposed robot is able to have omni-directional mobility.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.23-29
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• 2016

The Second Shutdown Drive Mechanism (SSDM) provides an alternate and independent means of reactor shutdown. The Second Shutdown Rods (SSRs) of SSDMs are poised at the top of the core by the hydraulic force driven from a hydraulic system during normal operation. The rods drop by gravity when a trip is commended by a Reactor Protection System, Alternate Protection System, Automatic Seismic Trip System or operator by means of power off solenoid valves of hydraulic system. This paper describes the test results of seismic qualification of a prototype SSDM hydraulic system to demonstrate that its structural integrity and operability (functionality) are maintained during and after seismic excitations, that is, an adequacy of the SSDM design. From the results, this paper shows that the SSDM hydraulic system satisfies all its design requirements without any malfunctions during and after seismic excitations.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.552-558
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• 2016

A control rod drive mechanism(CRDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod within a reactor core to control the reactivity of the core. The CRDM for Jordan Research and Training Reactor with 5MW power has been designed and fabricated based on the HANARO’s experience through KAERI and DAEWOO consortium. This paper describes the seismic test results to demonstrate the operability, the drop performance and the structural integrity of CRDM during or after seismic excitations. The seismic tests are carried out under 5 OBE and 1 SSE loads at three Test Rigs simulating the reactor structure and the pool top. From the tests, the CRDM is smoothly driven without a malfunction of stepping motor under OBE load. The pure drop time under OBE and SSE loads is measured as 1.169s and 1.855s to meet the design requirement. Also, it is found that the CRDM maintains the structural integrity without a change of the function and natural frequency before and after seismic loads.

• 정보저장시스템학회논문집
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• 제3권4호
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• pp.196-201
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• 2007

As the demand for the lap-top computer has been increased, most users ask quiet environment to work comfortably. Therefore, noise problems of an ODD are of great interest. For the high speed ODD, the flow induced noise is caused by the turbulent flow[1], which is known to be a major source of overall noise of a slim type ODD. In this study, we introduce a new attempt to reduce the noise level using the concept of Helmholtz resonator[2].The experimental analysis is carried out for several cases at different resonance frequencies and different hole patterns. The results show reductions in the noise level from the acoustic noise absorption point of view.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.241-244
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• 2006

Recently wind turbines become large, constructed as farms and going out to offshore. Different design approach from onshore is needed for offshore wind turbine. At this paper concept and preliminary design of an offshore wind turbine of 3MW rated power are performed. The concept design started from modelling of the generator and gearbox. With these modelling the optimum specifications was acquired. Integrated type of drive train is designed with all parts are mounted on the tower top as the offshore maintenance strategy. At the preliminary stage control system, power production algorithm and safety system are designed. Load calculation is also performed. The 3MW offshore wind turbine concept/preliminary design and the process of design are obtained as results.

• 산업경영시스템학회지
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• 제44권4호
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• pp.145-153
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• 2021

Automated Guided Vehicle (AGV) is commonly used in manufacturing plant, warehouse, distribution center, and terminal. AGV is self-driven vehicle used to transport material between workstations in the shop floor without the help of an operator, and AGV includes a material transfer system located on the top and driving system at the bottom to move the vehicle as desired. For navigation, AGV mostly uses lane paths, signal paths or signal beacons. Various predominant sensors are also used in the AGV. However, in the conventional AGV, there is a problem of not turning or damaging nearby objects or AGV in a narrow space. In this paper, a new driving system is proposed to move the vehicle in a narrow space. In the proposed driving system, two sets of the combined steering-drive unit are adopted to solve the above problem. A prototype of AGV with the new driving system is developed for the comparative analysis with the conventional AGV. In addition, the experimental result shows the improved performance of the new driving system in the maximum speed, braking distance and positioning precision tests.