• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.279.1-279.1
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• 2014

글래스(glass), 폴리머 또는 쿼츠와 같은 투명기판은 렌즈, 디스플레이, 광검출기, 광센서, 발광다이오드 및 태양전지와 같은 광 및 광전소자 분야에서 널리 사용되고 있다. 이러한 소자들의 경우, 광추출 또는 광흡수 효율을 향상시키는 것이 매우 중요하다. 그러나 투명기판의 경우, 약 1.5의 굴절율로 인해 표면에서 4% 반사가 발생되는데, 이러한 광학적 손실은 소자의 성능을 저하시키는 원인이 된다. 따라서, 글래스와 공기 경계면에서 발생되는 광손실을 줄이기 위한 효율적인 무반사 코팅이 필요하다. 최근, 우수한 내구성 뿐만 아니라, 광대역 파장 및 다방향성에서 무반사 특성을 보이는 서브파장 주기를 갖는 나노구조(subwavelength structures)의 형성 및 제작 공정에 관한 연구가 보고되고 있다. 이러한 나노구조는 경사 굴절율 분포를 가지는 유효 매질을 형성하기 때문에 투명기판 표면에서의 Fresnel 반사로 인한 광손실을 줄일 수 있다. 또한, 무반사 서브파장구조를 형성하기 위한 패터닝 방법으로, 간단/저렴하고 대면적 제작이 용이한 열적 응집 공정을 이용한 자가정렬된 금속 나노입자 형성 기술이 널리 사용되고 있다. 따라서 본 실험에서는 열적 응집현상에 의해 형성된 비주기적 금 나노입자 식각 마스크 패턴 및 유도결합 플라즈마 장비를 이용하여 글래스 기판 위에 무반사 서브파장 나노구조를 제작하였다. 금 나노패턴 및 제작된 글래스 서브파장 나노구조의 식각 프로파일은 주사전자현미경을 사용하여 관찰하였으며, UV-Vis-NIR 스펙트로미터를 사용하여 빛의 투과율을 측정하였다. 또한, 제작된 샘플들에 대해서, 표면 접촉각 측정 장비를 이용하여 표면 wettability를 조사하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.463-475
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• 2009

Flash memory is suitable for real time systems because of its consistent performance for random access, low power consumption and shock resistance. However, flash memory needs blocking time to perform a garbage collection to reclaim invalidated pages. Moreover, the worst-case garbage collection time is significantly longer than the best-case garbage collection time. In this paper, we propose a FTL (Flash Translation Layer) mapping scheme called KAST (K-Associative Sector Translation). In the KAST scheme, user can control the maximum association of the log block to limit the worst-case garbage collection time. Performance evaluation using simulation shows that not only KAST completes the garbage collection within the specified time but also provides about 10~15% better average performance than existing FTL schemes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.1-9
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• 2015

Due to the increasing number of deteriorated bridges worldwide, the importance of maintenance and replacement of existing bridges are being emphasized. Cast-in-place concrete deck which is mainly applied to deck replacement of existing bridges have problems such as deterioration concerns by initial crack, labor cost increase, difficulties of maintenance and replacement, construction time increase, and indirect cost increase by traffic congestion. On the contrary, a precast concrete deck is considered as an effective alternative because of its quality assurance and accelerated construction. The connection method ensuring the required strength and durability is especially important, because the connection part of the precast concrete deck is vulnerable to cracks and leakage. Therefore, this study proposes precast bridge decks with ribbed connection which are more improved than existing bridge deck joints, and flexural performance is verified through various parameter tests.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.685-690
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• 2006

The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as to locate the crane in the set position for loading and unloading containers. The wedge typed rail clamp should be designed to consider the structural stability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, the design of experiments(DOE) and the variation technology(VT) built in ANSYS WORKBENCH are utilized to determine the optimum shape of a jaw. The optimum results obtained by two methods are compared and examined.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.111-118
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• 1996

In order to improve the chemical durability of glass in the $Na_2O$-CaO-$SiO_2$ system, it was investigated in the effect of $B_2O_3$ and ZnO addition and changing amount of each composition, $Na_2O$, $Al_2O_3$, $Li_2O$. In this minimize the change of softening point of glass was as follow.(wt%)$B_2O_3$:3.36%, ZnO:2.88%, $Na_2O$:9.93%, $Al_2O_3$, $Li_2O$:0.19%, $SiO_2$:70.56%, CaO:11.22%, $K_2O$:0.14%

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.2 s.9
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• pp.89-97
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• 2003

Indirect tensile strength(IDT) test and resilient modulus(Mr) test were performed to evaluate experimental performance characteristics for the conventional and crumb rubber-modified(CRM) asphalt concrete using dry and wet processes asphalt. The IDT test was conducted under three temperatures(5, 10, 20$^{\circ}C$). According to the test results, it was shown that indirect tensile strength of CRM asphalt concrete was lower than that of the conventional one. However, toughness and maximum vortical strain of the CRM asphalt concrete were higher than those of the conventional one. The results of Mr test were presented that Mr of CRM asphalt concrete was higher than that of the conventional one. In addition, it was revealed that the overall laboratory performance characteristics of the wet-processed CRM asphalt concrete was better than those of the dry-processed one.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.193-197
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• 2009

In this paper, we study on design of vehicle control system which is based on ${\mu}C/OS-II$, We component a electric motor drive system for simulator because the most of vehicle part use electric motor for actuator. We use the XC2287 microcontroller which is often used vehicle body controller because XC2287 guarantee high confidence and durability in vehicle industry. The electric motor control system derive PWM from general I/O port in XC2287 microcontroller. The signal is supplied at electric motor after amplifying that using driver circuit. The user control duty of PWM signal through controlling potentiometer which is connected to XC2287. through that, the user control speed of electric motor. we synchronize both input process via controlling potentiometer and PWM output process using semaphore. we verify porting of ${\mu}C/OS-II$ via experimentation.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.589-596
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• 2002

In this paper, setting and strength performances of concrete containing saccharic type super retarding agents are investigated under various kinds and contents of super retarding agents. According to test results, as super retarding agents contents increase, slump shows to be increased, while air contents decrease about 1∼2％. Setting time shows to be retarded considerably with increase of super retarding agents. It takes 20 days after mixing to reach final setting in case of concrete containing gluconic acid more than 0.3％. And 10 days after mixing in case of enhancing sucrose, white and brown sugar. Compressive strength of concrete containing super retarding agents is lower than that of plain concrete at early age. However, it keeps up with and exceeds the compressive strength of plain concrete at later age. White sugar md brown sugar shows positive performances in delaying setting time and strength compared to existing super retarding agents. n further investigations on durability are conducted, it is thought that application of white sugar as super retarding agent is available.

• Journal of the Korean GEO-environmental Society
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• v.18 no.11
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• pp.35-40
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• 2017

The rearside of concrete lining of tunnels constructed in cold region might experience on freezing due to the low temperature. This causes damage of concrete lining resulting in adverse affect on the durability as well as integrity of tunnel structure by causing damage to the concrete lining. In order to prevent the rearside of tunnel lining from freeing, the temperature change inside the concrete lining was measured by attaching a heating element to the tunnel lining surface and generating heat for a certain period of time. A special freezing chamber was developed to conduct the experiments considering in-situ environment. The carbone nanotube (CNT) was used as a heating element in this study. The temperature distribution of the concrete lining was measured by applying the heat to the heating element. The effect of the outside temperature and heating duration were analyzed.