• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1992.11a
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• pp.13-18
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• 1992

대형 틸팅패드 저어널베어링은 고속안정성 특성이 우수한 베어링으로서 시스템의 안정성이 매우 중요시되는 터빈발전기 등 대형 고속 회전기계에 많이 사용되고 있다. 그런데 이들 대형 저어널베어링에서는 유막의 온도상승이 매우 많고, 유체의 흐름이 거의 난류영역에 이르기 때문에 베어링의 운전특성을 정확하게 예측하기가 어려운 실정이다. Hopf & Schuler는 대형 틸팅패드 저어널베어링에 대한 실험적 연구에서 유동상태에 따라 베어링의 온도분포가 서로 달라진다고 발표하였다. 대형 틸팅패드 저어널베어링은 구조적으로 유동상태가 복잡할 뿐만 아니라 계산과정도 까다로운 편이어서 온도상승과 난류를 고려하여 엄밀하게 운전특성을 예측한 연구는 거의 없다. 따라서 본 연구에서는 대형 틸팅패드 저어널베어리으이 운전특성을 보다 엄밀하게 예측하기 위하여 3차원 적으로 유막의 점도변화 및 패드에서의 열전달을 고려하고, 와점성계수를 이용한 난류윤활이론을 사용하여 유막의 온도상승 및 난류가 베어링의 온도분포, 부하능력, 마찰손실 등의 운전특성에 미치는 영햐을 보다 엄밀하게 제시하고자 한다.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.335-340
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• 2020

The purpose of this study was to compare the dynamic behavior of STEDEF track that of the sleeper floating track on urban rapid transit according to replacing the resilience pads and analyze the necessity of replacing the resilience pads experimentally. It was analyzed that the uniformity of the track support stiffness could be secured by replacing the used resilience pads with new resilience pads. Therefore, by replacing the used resilience pads, the measured track impact factor was found to be dramatically reduced below the track design standard, and it was analyzed that the track support stiffness could be restored to the design value. As a results, it is possible to restore track support stiffness to the design value and reduce track impact factor by replacing timely resilience pads, which is important to securing durability and improving service life of track components.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.38-45
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• 2022

Due to the development of fintech technology, financial transactions using smart phones are being activated. The password for user authentication during financial transactions is entered through the virtual keypad displayed on the screen of the smart phone. When the password is entered, the attacker can find out the password by capturing it with a high-resolution camera or spying over the shoulder. A virtual keypad with security applied to prevent such an attack is difficult to input on a small touch-screen, and there is still a vulnerability in peeping attacks. In this paper, the entire keypad is divided into several groups and displayed on a small screen, touching the group to which the character to be input belongs, and then touching the corresponding character within the group. The proposed method selects the group to which the character to be input belongs, and displays the keypad in the group on a small screen with no more than 10 keypads, so that the size of the keypad can be enlarged more than twice compared to the existing method, and the location is randomly placed, hence location of the touch attacks can be blocked.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.6
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• pp.814-820
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• 2009

The arrangement of the general 12-button cellular phone keypad is unified with one or two kind. In general, the several alphabets are arranged in one key. When inputting an English, countries which do not speak English use multi-tap method. We can input next alphabet by pressing key repeatedly. We address the problem of finding multi-tap-based keypad designs which minimize the number of key presses for various case. Genetic algorithms is proposed method for optimal keypad designs. We are to maintain the number of keys, which is ranged from 8 to 12. We also show experimental using non-alphabetically-constrained and alphabetically-constrained arrangement, respectively. Finally, we give improved keypad designs.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.571-575
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• 2004

인쇄회로기판(PCB)을 조립 또는 검사하는 장비의 작업 프로그램 작성을 위해서는, 납땜 패드의 위치와 크기에 대한 데이터가 필요하다. CAD 파일, 거버 파일 등을 사용하여 패드를 추출하는 방법이 많이 사용되고 있으나, 본 논문은 이미지 스캐너를 사용하여 추출하는 방법을 새로이 제안한다. 제안된 방법은 통계적 영상 처리를 적용하여, 기존의 일반적인 영상처리 방식보다 기판 별 패드 색상의 차이에 강인하다. 실제 PCB 에 대한 실험을 통하여 제안 방법의 성능을 검증한다. 제시된 방법은, CAD 파일과 거버 파일의 확보가 어려운 임가공 업체 등의 생산현장에서 사용될 수 있다.

• Review of KIISC
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• v.21 no.7
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• pp.30-37
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• 2011

보안 키패드는 사용자가 스마트폰을 이용하여 금융 거래를 할 때 사용자가 입력한 패스워드의 터치 좌표가 노출되더라도 키 값을 유추할 수 없도록 한 보안 애플리케이션이다. 하지만, 현재 상용화된 보안 키패드는 좌표값 노출에 따른 키값 노출을 막기 어려우며, 특히 휴리스틱 분석이나 사전 공격(dictionary attack)등에 취약한 문제가 있다. 본 논문에서는 현재 사용되는 보안 키패드의 취약점을 분석하고, 이러한 취약점을 해결하기 위한 몇 가지 개선 방안을 제안한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.71-72
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• 2024

본 논문에서는 Adobe Mixamo, 에픽게임즈 마켓플레이스, 유니티 에셋스토어 등에서 제공되는 모션캡쳐 FBX 데이터를 3ds Max 바이패드 애니메이션 시스템에 리타게팅 적용할 때 발생하는 문제점과 해결 방법을 살펴본다. 모션캡쳐 FBX를 바이패드에 리타게팅 하는 과정은 다양한 측면에서 이슈가 발생하는데 본 논문에서는 종아리와 하박 관절의 X축 회전 오차를 중심으로 살펴본다.

• Journal of Bio-Environment Control
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• v.14 no.2
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• pp.76-82
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• 2005

Evaporative cooling pad system is one of the main cooling methods in greenhouses and its efficiency is very high. However, it has some disadvantages such as greenhouse temperature distributions are not uniform and installation cost is expensive. In this study, a CFD simulation model f3r predicting the air temperature distribution in the fan and fad cooling greenhouse was developed. The model was calibrated and validated against experimental data and a good fit was obtained. The influence of different outside wind, fan and pad height, ventilation rate, shading, and greenhouse length, were then examined. In order to reduce the internal temperature gradients, it is desired that the prevail wind direction and the fan and pad heights are considered. The simulation indicates that high ventilation rates and shading contribute to reduce the temperature gradients in the fan and pad cooling greenhouse. In order to maintain the desired greenhouse temperature, the pad-to-fan distance should be restricted according to the design climate conditions, shading and ventilation rates. The developed CFD model can be a useful tool to evaluate and design the fan and pad systems in the greenhouses with various configurations.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.33-42
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• 2015

The vertical static stiffness of rail pads or baseplate pads, which are important components in rail fastening systems for track safety, is a key factor to determine the total track stiffness and a guideline of quality control in the manufacturing process. The vertical static stiffness can be checked by laboratory testing: test methods are EN 13146-9 and KRS TR 0014, which are widely used in the railway field. In this paper, to correct some problems, namely the preloading step, the unloading level, and the holding time in the loading program in the vertical static stiffness test of EN 13146-9 and KRS TR 0014, domestic and foreign test standards of pads were analyzed and then certain schemes for a vertical static stiffness test were proposed. To assess the reliability of the proposed schemes, the vertical static stiffness tests were performed with 4 pads and the validity of the test results was estimated.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.100-108
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• 2011

This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.