• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.405-411
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• 2014

It needed the calculation of the required tugboat's power to move the damaged vessel to the safe area for reducing the additional damages. In this paper, it was verified the theoretical calculation method on the required power of tugboat through the 93m real ship tests. From the experiments, it was considered that the theoretical calculation method was sufficient to estimate the required power of tugboat. The resistance of the locked propeller was relatively big portions compared with other static resistances such as air resistance, frictional resistance and residual resistance. And dynamic resistance induced by swing movement and yawing was continuously occurred and it also was great effects on the total resistance. In the future, the safety factor will be considered and the exact prediction of ship's resistance will enhance the efficiency of tugboat because of the minimization of safety factor.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.224-230
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• 1998

The relationships between R-H curves of gaint magnetoresistance (GMR) spin valve trilayer films and M-H curves of each magnetic layer consisting of the trilayer films were analyzed and simple formula representing the relations between the curves were suggested for theoretical analysis and study of magnetoresistance (MR) in those films, especially where the MR is from the difference of coercivity. Using two kinds of NiFe/Cu/Co films, which had been deposited on Cu(50 $\AA$)/Si(111, 4$^{\circ}$ tilt-cut) and Cu(50 $\AA$)/glass, R-H and M-H curves were measured and compared with the calculated ones, which were obtained by appying the M-H curves of single NiFe and Co films, deposited on the same substrates, to the previously reported single-domain and multi-domain models. The calcuated ones were well consistent with the measured ones and the suggested simple relationships between R-H and M-H curves are thought to be very useful for the deep understanding of MR behavior and the reasonable approach to improve MR properties in GMR spin valve trilayer films.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.50-62
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• 1994

This paper presents the results of a comparative analysis of the model test results to investigate the effect of bulbous bow installed on a large full form ship to the ship resistance performance. Seven parameters related to the shape of bulbous bow were selected and varied systematically to inquire their effects experimentally. A total number of twenty-three ship models with different bulbous bow were manufactured, and resistance tests. flow visualization test, and wave profile measurement were carried out for each model. For the comparative analysis between the various bulb forms and their model test results, bulbous bow forms are classified into nine groups according to their form characteristics. From the analysis of the trend of the resistance components, it was verified that form resistance has dominant effect on the total resistance of a slow full form ship. The model test and its statistical analysis showed that the direction of streamlines around bulbous bow has close relationship with resistance components. especially with form resistance

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.14-22
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• 2001

This paper presents the results of hull form design and powering performance for a 2.500 ton class trimaran frigate. A series of resistance tests and numerical calculations have been conducted to figure out the influences of side-hull form and position on the resistance characteristics of the trimaran. And the propulsion test was conducted to investigate the propulsion efficiency of the trimaran, and the powering performance of the trimaran was compared with that of the similar mono-hull ships in full scale. From the research it was found that the longitudinal position of side-hull had a large influence on the resistance characteristics of the trimaran while the side-hull form and transverse position had a small influence on it. The trimaran showed favorable resistance performance when the side-hull was located near the stern of trimaran, which was resulted from the fact that the side-hull stem was located near the primary wave hollow generated by the main hul1. The powering performance of the trimaran was superior to that of the similar mono-hull ships above the middle speed range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.1-8
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• 2019

Most of rotor resistance estimators utilizes Classical qd Model (CQDM) and Alternate qd Model (AQDM). The rotor resistance estimators based on both models were shown to provide an accurate rotor resistance estimate under conditions where flux is constant such as a field-oriented control (FOC) based induction motor drives. Under the conditions where flux is varying such as a Maximum torque per amp (MTPA) control, AQDM based rotor resistance estimator estimates actual rotor resistance accurately even in different operating points. However, CQDM based rotor resistance estimator has not been investigated and its performance is questionable under condition where flux level is varying. Thus, in this work, the performance of CQDM based rotor resistance estimator was investigated and made comparisons with AQDM based estimator under conditions where flux level is significantly varying such as in MTPA control based induction motor drives. Unlike AQDM based estimator, the laboratory results show that the CQDM based estimator underestimates actual rotor resistance and exhibits an undesirable dip in the estimates in different operating points.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.51-54
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• 2006

최근 국내 중형급 조선소에서는 케미컬 탱커선을 주력선종으로 건조하고 있다. 하지만 선형개발 기술이 미비하여 저항감소 선형개발에 소홀하였다. 또한 기존 대형선박의 선형을 그대로 사용하기 때문에 추진효율이 떨어지고 많은 선수저항이 발생하여 선속에 큰 영향을 미치게 된다. 이에 본 연구에서는 CFD이론 해석을 통해 선형특성을 파악하고 저항감소 및 추진 효율 향상을 위해 실적선과 개발대상선의 모형시험을 통하여 선수저항 성능을 비교, 분석하여 저항감소 선수선형을 개발하였다.

• Journal of the Korean Vacuum Society
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• v.4 no.2
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• pp.164-171
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• 1995

열처리에 따른 Cu 박막의 미세구조 및 전기 비저항의 변화를 조사하였다. Cu(hfac)(TMVS)를 원료로 하는 저압화학증착법에 의해 증착온도를 $160^{\circ}C$에서 $330^{\circ}C$까지 변화시키면서 TiN기판 위에 Cuqkr막을 제조하였고 $450^{\circ}C$에서 30분간 열처리하였다. 증착온도에 따라 표면이 평평한 Cu 박막을 형성하는 표면반응 제한지역과 표면이 거친 Cu 박막을 형성하는 물질전달제한지역이 관찰되었다. 열처리 후 Cu 박막은 전체적으로 표면이 평탄해졌고 결정립의 크기는 모든 증착온도에서 증가하였는데 그 편차 역시 증가하여 EM 저항성 측면에서는 큰 효과를 보이지 못할 것으로 판단된다. 비저항은 증착온도 $200^{\circ}C$에서 급격히 증가하였고 열처리 후에는 모든 증착온도에서 비저항이 감소하였는데 표면반응제한지역에서는 결정립 성장에 의한 약간의 비저항 감소를 보였으나 물질전달제한지역에서는 응집에 의해 Cu 결정립간의 전기적 연결상태가 향상되어 급격한 비저항 감소를 보였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.01a
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• pp.137-139
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• 2016

본 논문에서는 압저항 소재 및 센서 기술과 ICT 응용 기술에 대해 소개한다. 먼저 압저항 소재의 구성 및 작동원리를 소개하고, 한국표준과학연구원에서 개발한 유연한 압저항 센서의 구성과 성능에 대해 기술한다. 또한, 개발된 압저항 센서와 ICT 기술을 융합한 스마트 안전 시스템 및 스마트 창호 침입감지 시스템에 대해 기술한다. 마지막으로, ICT기술을 기반으로 압저항 센서기술이 확장해 나아가야 할 스마트 보안 시스템 개발의 필요성을 기술한다.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.158-160
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• 2002

초정밀 박막저항을 제조하기 위하여, 3원계 5lwt%Ni-4lwt%Cr-8wt%Si 합금 타겟(Target)을 가지고 DC/RF 마그네트론 스퍼터를 이용하여 박막 저항을 제조하였고. 낮은 저항온도계수(TCR)를 가지는 박막을 만들기 위해 스퍼터링 제조공정의 변화에 따른 박막의 미세구조와 전기적인 특성을 조사하였다. 스퍼터링 제조공정 변수로써 스퍼터링 Power를 변화시켰고. 제조된 박막은 공기 중에서 400[$^{\circ}C$]까지 열처리하였다. 반응압력을 감소시킴에 따라 TCR값은 감소하였고, 기판온도 및 열처리 온도의 증가에 따라 TCR값도 증가하였다. 또한. 저항온도계수값은 DC와 RF의 변화에 따라 +52, -25(ppm/$^{\circ}C$)의 TCR값을 나타냈다 이와 같은 결과로부터 제조공정을 변화시킴에 따라 면저항 및 저항 온도계수의 제어가 가능함을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.73-73
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• 2006

본 연구의 목적은 배전선로 접지극의 온도변화 및 토양동결 상태에 따른 접지저항값의 변화를 관찰하고, 영상과 영하의 온도와 접지저항값 변화의 상관관계를 분석하여 접지저항값 변화를 최소화하는 데 있다. 온도변화에 따른 접지저항값 변화의 최소화를 이루기 위하여 접지극과 토양의 접촉저항을 최소화하는 방안을 연구 하였으며, 이를 현장에 적용하여 검증한 결과, 접지저항값의 변화가 최소화되는 우수한 성과를 거양하여 각종 접지공사의 설계시 활용할 수 있도록 하였다.