한국의 컨벤션 안전대책에 관한 연구

이건찬(Kun Chan Lee),안경모(Kyung Mo Ahn) 한국호텔관광학회 2002 호텔관광연구 Vol.4 No.1

As the globalism and liberalization trend spread throughout the wold, the convention industry has been recognized as a new high value-added business. In order to foster the convention industry as a national strategic industry, we are making marketing efforts to establish, expand and maintain convention-related facilities. Therefore, this research will cover the followings: First, through examination of theoretical basis on conventional operation, terminate anticipated threats during the convention period, Second, through analyzing investigation and survey reports related to safety measures in conventions hosted in Korea, examine the practicality and applicability of those examples to present safety measures contemplated, and Third, based on the analysis above, contribute to the successful hosting of conventions by discussing methods to guarantee individuals and facilities from anticipated threats during the convention period in four categories of (1) security activities, (2) VIP escorts, (3) prevention of cyber terrorism and (4) counter-measures against emergencies.

SiO₂ 나노 콜로이달 첨가량에 따른 Si₃N₄의 고온강도 특성

남기우,이건찬,Nam, Ki-Woo,Lee, Kun-Chan 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.11

This study analyzed the characterization of high temperature strength of $Si_3N_4$ composite ceramics additive based on variations in the amount of nano colloidal $SiO_2$ added. Semi-elliptical cracks about 100 ${\mu}m$ length were obtained from a Vickers indenter using a load of 24.5 N. The results showed that the heat-treated smooth specimens with $SiO_2$ nano colloidal coating exhibited the highest bending strength at 0.0 wt% $SiO_2$ nano colloidal added, which is amounted to a 187 % increase over that of smooth specimen. Limiting temperature for bending strength of crack-healed zone for bending strength was about 1273 K. However, the bending strength of SSTS-3 and SSTS-4 was considerably increased while that of SSTS-1 and SSTS-2 was decreased at a temperature of 1,573K.

SiC/SiC 복합재료 세라믹스 표면균열 탐지를 위한 초음파법 적용에 관한 기초연구

남기우(Ki Woo Nam),이건찬(Kun Chan Lee),香山晃(Akira Kohyama) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.5

세라믹스의 비파괴평가 기술은 산업분야에 응용하기 위한 세라믹스 신뢰성 개발에 있어서 필수적인 기술이다. 본 연구는 초음파 C-Scan 방식을 이용하여 SiC 세라믹스의 표면균열을 탐상하기 위한 실험적 연구결과를 제시하고자 한다. 이를 위해 SDS-win과 μ-SDS 두 종류의 초음파 장치와 25, 50 및 125 ㎒의 초음파센서를 이용하여 세라믹스의 표면균열 탐상 가능성에 대해 실험적인 연구를 수행하였다. 본 연구 결과, 세라믹스의 표면미소균열은 결국 25 및 50 ㎒ 센스로 정밀하게 검출할 수 없었으나, 125 ㎒ 센서에 의한 집속법 탐상 결과 희미한 형상 정도를 검출할 수 있었으며, 비집속법의 경우는 비커스 압입자의 형상 검출이 가능함을 알 수 있었다. 따라서 본 연구를 통하여, 초음파 C-Scan 집속 및 비집속 방법은 미세균열의 탐상방식으로 어느 정도 접근 가능함을 실험적으로 확인하였다. Nondestructive evaluation(NDE) of ceramic matrix composites is essential for developing reliable ceramics for industrial applications. In the work, C-Scan image analysis has been used to characterize surface crack of SiC ceramics nondestructively. The possibility of detection of surface crack were carried out experimentally by two types of ultrasonic equipment of SDS-win and μ-SDS, and three types of transducer of 25, 50 and 125 ㎒. A surface micro-crack of ceramics was not detected by transducer of 25 ㎒ and 50 ㎒. Though the focus method was detected dimly the crack by transducer of 125 ㎒, the defocus method could detect the shape of diamond indenter. As a whole, the focus method and the defocus method came to the conclusion that micro crack have a good possibility for detection.

시간-주파수 해석법에 의한 5083 알루미늄의 피로균열 진전에 의한 음향방출 신호의 주파수특성

남기우(KI-WOO NAM),이건찬(KUN-CHAN LEE) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.3

Acoustic emission (AE) signals, emanated during local failure of aluminum alloys, have been the subject of numerous investigations. It is well known that the characteristics of AE are strongly influenced by the previous thermal and mechanical treatment of the sample. Possible sources of AE during deformation have been suggested as the avalanche motion of dislocations, fracture of brittle particles, and debonding of these particles from the alloy matrix. The goal of the present study is to determine if AE occurring as the result of fatigue crack propagation could be evaluated by the joint time-frequency analysis method, short time Fourier transform (STFT), and Wigner-Ville distribution (WVD). The time-frequency analysis methods can be used to analyze non-stationary AE more effectively than conventional techniques. STFT is more effective than WVD in analyzing AE signals. Noise and frequency characteristics of crack openings and closures could be separated using STFT. The influence of various fatigue parameters on the frequency characteristics of AE signals was investigated.

SiO₂ 나노 콜로이달 첨가량에 따른 Si₃N₄의 고온강도 특성

남기우(Ki Woo Nam),이건찬(Kun Chan Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.11

This study analyzed the characterization of high temperature strength of Si₃N₄ composite ceramics additive based on variations in the amount of nano colloidal SiO₂ added. Semi-elliptical cracks about 100 m length were obtained from a Vickers indenter using a load of 24.5 N. The results showed μ that the heat-treated smooth specimens with SiO₂ nano colloidal coating exhibited the highest bending strength at 0.0 wt% SiO₂ nano colloidal added, which is amounted to a 187 % increase over that of smooth specimen. Limiting temperature for bending strength of crack-healed zone for bending strength was about 1273 K. However, the bending strength of SSTS-3 and SSTS-4 was considerably increased while that of SSTS-1 and SSTS-2 was decreased at a temperature of 1,573K.

표면균열재의 피로균열 관통거동에 따른 어코스틱에미션

남기우(Ki-Woo Nam),김선진(Seon-Jin Kim),이건찬(Kun-Chan Lee),오정환(Jung-Hwan Oh),오세규(Sae-Kyoo Oh),이주석(Joo-Suk Lee) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.3

Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.

0.2% N을 첨가한 수퍼 2상 스테인리스강의 열처리 조건에 따른 특성 평가 : 제3보: 부식특성

안석환(Seok-Hwan Ahn),강흥주(Heung-Joo Kang),서현수(Hyun-Soo Seo),남기우(Ki-Woo Nam),이건찬(Kun-Chan Lee) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.5

A stainless steel that contains aggressive negative ion was known to decrease the corrosion resistance. Stainless steel with super corrosion resistance was developed for improvement of corrosion resistance. Super duplex stainless steel is widely used under sever environment because if good mechanical properties and corrosion resistance. Also, Super duplex stainless steel has long life in severe environments by showing the enough strength and corrosion resistance. But duplex stainless steel is not stabilized compared to austenite stainless steel in corrosion resistance. In this study, corrosion characteristic were investigated to super duplex stainless steel with additive 0.2 % nitrogen with SiO₂ thin films coated or no coated by sol-gel method in 3.5% NaCl. From test results, corrosion current density in the heat-treated specimen for σ phase precipitation was higher than that of different heat-treated specimen. Also, SiO₂ colloidal-coated specimen had not occurred almost corrosion.

열화된 SUS 316강의 시간-주파수 해석에 의한 비파괴평가

이주석,오정환,이건찬,남기우 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.4

지금까지 퓨리에 변환이 신호 처리법으로 가장 널리 사용되고 있다. 그러나, 이 방법은 신호의 주파수 성분이 시간에 대하여 어떻게 변화하는지를 표현하지 못한다. 따라서, 최근 이와같이 비정상신호를 표현하지 못하는 퓨리에 변환의 단점을 보완하여, 신호의 시간과 주파수에 대한 정보를 동시에 표현할 수 있는 시간-주파수 해석법들이 개발되기 시작하였다. 본 연구에서는 인공열화된 SUS 316강의 초음파 신호를 시간-주파수 해석법으로 분석하였다. 특히, 단시간 퓨리에 변화법과 위그너 빌 분포법을 이용하여 초음파 신호의 주파수 성분과 특성을 분석하였다. Fourier transform has been one of the most commonly used tools in study of frequency characteristics of signal. However, based on the Fourier transform, it is hard to tell whether a signal's frequency contents evolve in time or not. Recently, to overcome Fourier transform fault, not to represent non-stationary signal, time-frequency analysis methods are developed and those can represent informations of signal's time and frequency at the same time. In this study, we analysed ultrasonic signal for degraded SUS 316 with time-frequency analysis method. In particular, the methods such as short time Fourier(STFT) and Wigner-Ville distribution(WVD) were used to extract frequency contents and characteristics from ultrasonic signals.