• Journal of Ship and Ocean Technology
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• 제11권1호
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• pp.36-46
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• 2007

The maintenance of a ship is essential for safe navigation and hence regular surveys are prescribed according to the rule of classification societies. A hull inspection is generally performed by professional divers, but it takes a long time and the efficiency is low in terms of time and cost. In this research, a ROV(Remotely Operated Vehicle) named as SNU-ROV(Seoul National University-ROV) is developed to replace the conventional inspection method. In this system, the ROV is intended to be used for inspecting ship and harbor because harbor inspection is merging as a safety measure against any possible terror actions. In order to increase the efficiency of inspection, the ROV must be able to measure the exact position of damages. SNU-ROV has a positioning system based on LBL(Long Base Line). In shallow water such as harbor, however, LBL has bad DOP(Dilution of Precision) in the depth direction due to the limited depth. Thus LBL only can not locate the exact depth position. To solve the DOP problem, a pressure sensor is introduced to LBL and a complementary filter is attached by using indirect feedback Kalman filter. Thus developed positioning system is verified by simulation and experiment in towing tank.

• 조명전기설비학회논문지
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• 제12권1호
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• pp.12-19
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• 1998

본 논문에서는 와전류센서를 장착하고 전선위를 자동으로 주행하도록 설계된 부식 검출장치를 이용하여 ACSR의 내부부식 검출에 대해서 다룬다. 또한 내부부식의 검출은 비파괴검사로 행해진다. 독특한 ACSR의 구조에 의한 부식현상을 와전류센서를 이용하여 검출하는 경우, 부식은 센서의 임피던스변화로 검출되고 이 현상을 이론적으로 증명한다. 또한 설계된 부식검출장치의 사양과 성능 그리고 실험방법에 대해 논하고, 현장에 적용가능한 실험결과를 얻었다. 이 부식검출장치는 ACSR의 내부부식을 비파괴로 검출할 수 있고 현실적이라는 결론을 얻었다. 피시험체인 도체의 피복여부에 관계없이 이장치는 이용가능하고, 이 장치의 실용화에 의해 선로의 유지보수의 효율을 증대시키고 선로의 향상이 기대된다.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.455-462
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• 2023

In this study, an automatic spraying lubrication system was developed to maintain the cleanliness of the switchgear when detecting the movement of the track through the switchgear. To develop this system, an air tank, valve block, and spray nozzle were designed, and the safety was secured through the pressure test of the prototype after designing the air tank. Furthermore, the environmental aspect was considered by minimizing the use of lubricant by enabling the mixing of air and lubricant through the production of a valve using the Venturi principle. The performance evaluation was conducted by implementing (producing) the injection system, and the product developed in this study was deemed installable in actual switchgear. It is expected that the proposed system will enable the maintenance of the cleanliness of the track during switching and reduce faults and malfunctions caused by switchgear defects.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.82-92
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• 2011

This paper presents a PFC(Power Factor Correction) system to control the power factor of input current of the converter system which is working in the propulsion system of KTX high speed train. In the KTX train system, initially introduced from ALSTOM, the thyristor converter with phase controlling technique is adopted in the current fed type powering system. The input current induces harmonic losses highly because the waveform becomes rectangular shapes according to the filter inductor current increased as the train speed increasing gradually. Especially the interference with the signalling systems is severe concerned due to high current harmonics on the catenary line. To protect this problem, a frequency trap filter(notch filter) is operating with the input converter system. In this paper, an analysis work and PC simulation have been done on the PFC system to upgrade its performance and maintenance efficiency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1269-1274
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• 2011

To cut down the maintenance expenses at branch lines, the foreign developed countries have developed the low-cost signalling on low-density lines. These examples are FFB(FunkFahrBetrieb) Radio based train operation by German railways(Deutsche Bahn AG), ERTMS REGIONAL by Europe and LOCOPROL system using a GPS. Also, Korea is developing Information and Communication Technology based low-cost signalling on low-density lines. The characteristics of this system are directly controled switch and crossing by driver. For the purpose of this paper, we reviewed the business process for switch and crossing control. Specially, we compared and analysed both methods whether the driver takes control over the operation procedures of switch or the control message is carried by the command of the controller. And by utilizing the instrument of UML, I planned the switch according to the control authority and the operation procedures needed for the control of crossing.

• 설비공학논문집
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• 제24권1호
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• pp.85-89
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• 2012

This study has been conducted to compare two cargo handling systems on MR tanker and Panamax tanker. Submerged hydraulic cargo pumps with hydraulic power packs and frequency converter controlled electric deepwell pumps will be investigated and compared on all aspects of initial cost, installation, operation and maintenance. The result of investigation shows Electric Systems have less manufacturing costs, higher environmental friendliness and reliable operation compare to Hydraulic Systems. Furthermore, the present experimental data will provide important database for Electric Systems onboard new ships and practical and empirical guidelines are constructed for further determine the design of the Electric Systems.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.739-744
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• 2000

Concrete structures generally have cracks, so for the safety and durability of structures, studies to detect cracks using nondestructive tests have been treated in great deal. In order to assure the reliability of concrete structure, microscopic fracture behavior and internal damage progress of concrete under the loading should be fully understood. The purpose of this study predicts location of initial crack and measures direction of crack propagation for on-line monitoring before the crack really grows in structures by using two-dimensional Acoustic Emission(AE) source location based on rectangular method with three-point bending test. This will allow efficient maintenance of concrete structure through monitoring of internal cracking based on AE method.

• Journal of Positioning, Navigation, and Timing
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• 제9권2호
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• pp.125-129
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• 2020

In this paper, Zero velocity UPdaTe (ZUPT) is implemented on the navigation system of Remotely Piloted Aircraft for GNSS denied environment. RPA's navigation system suffers from lack or loss of satellite signal while maintenance or ground test inside a hangar. Although some of the hangars install GPS repeaters for indoor tests, the anti-jamming equipment with array antenna blocks the repeater signal regarding them as hostile jamming signal. With ZUPT, an aircraft navigation system can be tested free from the divergence of navigation solution without line-of-sight satellites. The designed ZUPT aided centralized Kalman Filter is implemented on the Embedded GPS&INS and simulated with Captive Flight Test data. The simulation result shows stable navigation solution without GNSS updates.

• Archives of Pharmacal Research
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• 제2권1호
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• pp.25-33
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• 1979

In order to find out nutritional effects of Korean edible mushrooms on the multiplication of tissue cells, the alcohol extracts and acid bydrolysates of eleven species of mushrooms were added to Earle's ESS. A comparison of the respective multiplications of HeLa cells in this solution and in control solution of TC=199. Yielded the following result: The alcohol extracts and acid hydrolysates of a Coprinus comatur, Agaricus campestris, Agaricus bisporus, Lentinus edodes, Tricholoma matsutake, Pleurotus ostretus, Ramaria botrytis and Pholiota nameko influenced favorably the maintenance of the normal form and monolayer of HeLa cells. The growth curves of HeLa cells in the cultures containing, respectively, the alcohol extracts and acid hydrolysates of these eight mushrooms showed that five species, i.e., Coprinus comatus, Agaricus compestris, Agaricus bisporus, Lentinus edodes and Tricholoma matsutake effected an excellent multiplication and that the other three species were less effective than those five species. As to the effects on the cell multiplication, no marked difference was observed between the alcohol extracts and the acid hydrolysates of the mushrooms tested.

• 한국정보통신학회논문지
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• 제9권8호
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• pp.1754-1761
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• 2005

사생활 보호에 대한 요구가 증가되고 있는 때 보안을 위한 모니터링 시스템의 요구는 날로 증가되고 있다. 본 논문에서는 인터넷을 통해서 PC나 PDA로 모니터링 할 수 있는 기술을 연구하였다. 마이크가 내장된 USB 카메라로 촬영한 영상과 음성 데이터를 H.263의 Multiplex를 통해서 인터넷을 통해 PC나 PDA로 전송한다. 그리고 웹 카메라 기반 홈서버용 모니터링 시스템 각 장치들의 동작 처리부를 일관된 구동 모듈로 통일하고, 관리자에게 일관된 구동 모듈을 제공하여 시스템의 운용과 관리에 있어서 편리함을 제공하였다.