• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1199-1202
• /
• 2007

The improvement of the electron injection is of critical importance for obtaining efficient and stable organic light-emitting diodes(OLEDs). Here, we report some of our recent results on the development of new cathode interlayer materials for OLEDs. Some of our new materials show performance superior to that of LiF.

• 정보보호학회지
• /
• 제17권2호
• /
• pp.9-23
• /
• 2007

The air interface supports a security layer which provides the key exchange protocol, authentication protocol, and encryption protocol. The authentication is performed on the encryption protocol packet. The authentication protocol header or trailer may contain the digital signature that is used to authenticate a portion of the authentication protocol packet that is authenticated. The encryption protocol may add a trailer to hide the actual length of the plaintext of padding to be used by the encryption algorithm. The encryption protocol header may contain variables such as the initialization vector (IV) to be used by the encryption protocol. It is our aim to firstly compute the session key created from the D H key exchange algorithm, and thereof the authenticating key and the encryption key being generated from the session key.

• 대한산업공학회지
• /
• 제41권3호
• /
• pp.225-232
• /
• 2015

The smart watch is the most popular wearable computing device because it takes a form of wristwatch. Many smart watches have adopted the touch screen interface due to the limited size of display. This paper focuses on touch key size and spacing that affect the usability about the touch key of smart watch. The experiments were made for four touch key sizes (width${\times}$height; $5{\times}5$, $5{\times}7$, $7{\times}5$, $7{\times}7mm$) and nine touch key spacing (vertical${\times}$horizontal; $0{\times}0$, $0{\times}1$, $0{\times}3$, $1{\times}0$, $1{\times}1$, $1{\times}3$, $3{\times}0$, $3{\times}1$, $3{\times}3mm$). The completion time, error rate, control discomfort and identification discomfort were measured. The touch key size $7{\times}7$, $7{\times}5$ and the touch key spacing $3{\times}3$, $1{\times}3$ provided the best results in terms of the completion time and the control discomfort, while the square touch key ($7{\times}7$, $5{\times}5$) provided the best performance for the error rate measure. The result of this study can help ergonomically design the touch interface of the smart watch.

• 한국HCI학회:학술대회논문집
• /
• 한국HCI학회 2006년도 학술대회 2부
• /
• pp.275-280
• /
• 2006

1990년대 휴대폰이 일반화가 시작된 이후 지금까지 수많은 종류의 휴대폰이 출시되어왔다. 종류가 다양해진 만큼 기능, 목적, 사용방법 또한 다변화 되었고, 이로 인해 매일같이 쏟아져 나오는 휴대폰의 기능 및 사용방법에 대해 유저들은 항상 새로운 방식을 익히도록 강요되고 있다. 이에 본 연구에서는 Key Card Arranging 기법을 활용하여 현재 모바일 기기 사용자들의 멘탈 모델에 적합한 최적의 Key Mapping에 대한 가이드라인을 제시함으로써 최소한의 노력으로 사용자들이 정보기기를 활용할 수 있도록 하는데 그 목적이 있다. 본 연구를 위하여 국내의 대표적인 6개 휴대폰 회사별로 선별된 테스트 서브젝트들을 선정하여 실험을 실시 하였으며, 구체적인 방법론은 다음과 같다. 우선 핸드폰 기기 내의 Hot Key에 대한 Key Mapping을 중심으로 Key Card Arranging 기법과 In-depth Interview 방법론을 활용하여 선정된 서브젝트들을 대상으로 사용자 멘탈 모델에 대한 데이터를 취합하였다. 취합된 자료를 중심으로 정량적 데이터 분석 방법을 활용, 사용자의 휴대폰 키 맵핑에 대한 이상적인 멘탈 모델을 제안하고, 최종적으로 본 연구를 통하여 사용자에게 최적의 경험을 제공하기 위하여 휴대폰 Key Mapping에 대한 가이드라인들을 제시한다.

• 한국세라믹학회지
• /
• 제56권3호
• /
• pp.284-290
• /
• 2019

Ternary MoS₂/graphene (G)-TiO₂ photocatalysts were prepared by a simple hydrothermal method. The morphology, phase structure, band gap, and catalytic properties of the prepared samples were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-vis spectrophotometry, and Brunauer-Emmett-Teller surface area measurement. The H₂ production efficiency of the prepared catalysts was tested in methanol-water mixture under visible light. MoS₂/G-TiO₂ exhibited the highest activity for photocatalytic H₂ production. For 5 wt.% and 1 wt.% MoS₂ and graphene (5MT-1G), the production rate of H₂ was as high as 1989 µmol^-1h^-1. The catalyst 5MT-1G showed H₂ production activity that was ~ 11.3, 5.6, and 4.1 times higher than those of pure TiO₂, 1GT, and 5MT, respectively. The unique structure and morphology of the MoS₂/G-TiO₂ photocatalyst contributed to its improved hydrogen production efficiency under visible light.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.469-474
• /
• 2002

Laser and hot air reflow soldering of PBGA solder ball was investigated. Experimental results showed that surface quality and shear strength of solder bumps reflowed by laser was superior than the solder bumps reflowed by hot air, and the microstructure inside the solder bumps reflowed by laser was much finer. Analysis on interfacial reaction showed that eutectic solder reacted with Au/Ni/Cu pad shortly after the solder was melted. Interface of solder bump reflowed by laser consists of a continuous AuSn$_4$ layer and remnant Au element. Needle-like AuSn$_4$ grew sidewise from interface, and then spread out to the entire interface region. A thin layer of Ni$_3$Sn$_4$ intermetallic compound was found at the interface of solder bump reflowed by hot air, AuSn$_4$ particles distributed inside the whole solder bump randomly. It is the combination effect of the continuous AuSn$_4$ layer and finer eutectic microstructure inside the solder bump reflowed by laser that resulted in higher shear strength.

• 대한인간공학회지
• /
• 제29권4호
• /
• pp.605-610
• /
• 2010

In order to design a touch interface for the elderly, human performance of input tasks on the touch screen was investigated by the laboratory experiment. Input times and input errors were measured in the experimental conditions that were changed according to age, key size, interkey space and input tool(finger or stylus pen). In the most of all experimental conditions, the task performance of the elderly was lower than that of the young. However, there were significantly different performance patterns between both groups. As the difficulty of task was getting higher, the task performance of the elderly was sharply decreased; pressing small key button by finger sharply increased input time and error rate, compared to that of the young. Therefore, the square key size suitable to the elderly may be over $8.0{\times}8.0mm$. While the interkey space did not influence to the input task performance of the young, the task performance of the elderly was influenced. The elderly showed big difference of task performance according to input tool. However, the young were less influenced by input tool.

• 융합보안논문지
• /
• 제7권3호
• /
• pp.61-70
• /
• 2007

Windows 운영체제는 응용프로그램이 쉽고 편리하게 다양한 암호화 알고리즘을 사용할 수 있도록 CSPs(Cryptographic Service Providers)를 제공하고 있으며, 이 응용프로그램은 CryptoAPI(Cryptographic Application Program Interface)를 통하여 선택적으로 다양한 CSP 모듈을 이용할 수 있다. 이 때 CryptoAPI와 CSP 모듈 사이에서 함수로 전달되는 파라미터의 분석을 방지하기 위해 핸들을 이용한 안전한 데이터 접근 방식을 사용하고 있다. 본 논문에서는 새롭게 제시한 메모리 역추적 기법을 통해 위와 같은 보안기법에서도 개인키/비밀키와 같은 중요한 데이터가 노출되는 취약점이 존재한다는 것을 실험을 통해 증명하였다.

• Computers and Concrete
• /
• 제14권1호
• /
• pp.91-107
• /
• 2014

Using the principle of damage mechanics, zero-thickness pore pressure cohesive elements (PPCE) are used to simulate the casing-cement interface (CCI) and cement-rock interface (CRI). The traction-separation law describes the emergence and propagation of the PPCE. Mohr-coulomb criteria determines the elastic and plastic condition of cement sheath and rock. The finite element model (FEM) of delamination fractures emergence and propagation along the casing-cement-rock (CCR) interfaces during hydraulic fracturing is established, and the emergence and propagation of fractures along the wellbore axial and circumferential direction are simulated. Regadless of the perforation angle (the angle between the perforation and the max. horizontal principle stress), mirco-annulus will be produced alonge the wellbore circumferential direction when the cementation strength of the CCI and the CRI is less than the rock tensile strength; the delamination fractures are hard to propagate along the horizontal wellbore axial direction; emergence and propagation of delamination fractures are most likely produced on the shallow formation when the in-situ stresses are lower; the failure mode of cement sheath in the deep well is mainly interfaces seperation and body damange caused by cement expansion and contraction, or pressure testing and well shut-in operations.

• Nuclear Engineering and Technology
• /
• 제51권4호
• /
• pp.1132-1141
• /
• 2019

Steel-concrete-steel (SCS) sandwich structures have important advantages over conventional concrete structures, however, bond-slip between the steel plate and concrete may lead to a loss of composite action, resulting in a reduction of stiffness and fatigue life of SCS sandwich structures. Due to the inaccessibility and invisibility of the interface, the interfacial performance monitoring and debonding detection using traditional measurement methods, such as relative displacement between the steel plate and core concrete, have proved challenging. In this work, two methods using piezoelectric transducers are proposed to detect the bond-slip between steel plate and core concrete during the test of the beam. The first one is acoustic emission (AE) method, which can detect the dynamic process of bond-slip. AE signals can be detected when initial micro cracks form and indicate the damage severity, types and locations. The second is electromechanical impedance (EMI) method, which can be used to evaluate the damage due to bond-slip through comparing with the reference data in static state, even if the bond-slip is invisible and suspends. In this work, the experiment is implemented to demonstrate the bond-slip monitoring using above methods. Experimental results and further analysis show the validity and unique advantage of the proposed methods.