• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.978-983
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• 2014

This research proposes a method to estimate the fatigue life of solid-state drive(SSD) due to the effect of dummy solder ball under forced vibration. Mechanical jig is developed to describe the SSD in laptop computer. The jig with SSD is mounted on a shaker, and excited by a sinusoidal sweep vibration within the narrow frequency band around the first resonant frequency until the SSD fails. A finite element model of SSD is also developed to simulate the forced vibration. It shows that the solder joints at the corners of controller package are most vulnerable components and that placing dummy solder balls at those area is effective method to increase fatigue life of SSD.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권4호
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• pp.175-182
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• 2000

The back-light inverter used in the laptop computer is designed in this paper. It has been difficult for electromagnetic transformer to enhance the efficiency and compact profile of the inverter. In this paper, (1) the piezoelectric transformer (PT) is used for reducing the loss; (2) the volumes of core and winding coil are used in electromagnetic transformer, and (3) the half-bridge series parallel resonant circuit is used in the driver of the inverter. The modified PT for this paper and the equivalent circuit are supported by the simulation program. The result of the experiment shows more than 91% improvement in terms of the efficiency.

• 한국전산유체공학회지
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• 제16권3호
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• pp.47-51
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• 2011

Dark Mura phenomena which can happen at the region with high temperature gradient in a Notebook LCD Monitor using LED light source has numerically been studied. The calculation was conducted under the nearly realistic conditions by considering the anisotropic thermal properties of materials and the real dimensions of each component. The two performance indices of LED monitor, i.e., the maximum temperature and the spacial gradient of temperature were examined for the various shapes, lengths and thickness of heat sink plate. Calculated results give more reasonable temperature distribution comparing with experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2043-2052
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• 2008

The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at $95^{\circ}C$.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.850-855
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• 2006

This is concerned with the development and design of automatic maneuvering system using Differential Global Positioning System(DGPS). To achievement of autonomous maneuvering controller for giant ship, first, we investigated automatic maneuvering controller using DGPS in motor car. The sensors are configured with DGPS and digital compass. We calculated velocity and steering angle of motor car based on sensor signal. To design the controller, we derived the bicycle model and developed critically damped controller. The critically damped controller can be tracing previously appointed position in the fastest time. We are used a laptop computer to realize and the control algorithm is programmed by visual basic software. The obtained experimental results from developed system show unmanned motor car is good tracing planed positions. Hence, the system is looking forward to use the autonomous maneuvering control fur giant ship.

• 중소기업융합학회논문지
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• 제4권4호
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• pp.19-23
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• 2014

Group communication is becoming increasingly popular in Internet applications such as videoconferences, online chatting programs, games, and gambling. For secure communications, the integrity of messages, member authentication, and confidentiality must be provided among group members. To maintain message integrity, all group members use the Group Key (GK) for encrypting and decrypting messages while providing enough security to protect against passive attacks. Tree-based Group Diffie-Hellman (TGDH) is an efficient group key agreement protocol to generate the GK. TGDH assumes all members have an equal computing power. One of the characteristics of distributed computing and grid environments is heterogeneity; the member can be at a workstation, a laptop or even a mobile computer. Member reordering in the TDGH protocol could potentially lead to an improved protocol; such reordering should capture the heterogeneity of the network as well as latency. This research investigates dynamic reordering mechanisms to consider not only the overhead involved but also the scalability of the proposed protocol.

• 디지털산업정보학회논문지
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• 제9권4호
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• pp.21-31
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• 2013

It is not easy to control the unstructured digital contents efficiently which are usually created while carrying out the wide scope of managerial activities. Moreover, besides the existing EDMS method, new methodologies including new-type servers and clients like SBC, VDI, thin client, zero client, etc are said to be more efficient for managing digital contents. Usually, digital contents has been created and stored in the dispersed individual computers like laptop or desktop. Today, due to the advent of new technologies and devices for computer systems and network capacity, it's possible to store whole digital contents within centralized storage like EDMS. In this paper, it is shown how digital contents can be controled through selection of which approaches are used for individual users and storage servers. For alternatives, we explained implementation, merits and demerits, selection criteria, etc. And a case of the implementation of digital contents control is shown for the reference of related systems.

• Journal of Computing Science and Engineering
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• 제5권4호
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• pp.331-337
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• 2011

Recently, Virtual Desktop Infrastructure (VDI) has been widely adopted to ensure secure protection of enterprise data and provide users with a centrally managed execution environment. However, user experiences may be restricted due to the limited functionalities of thin clients in VDI. If thick client devices like laptops are used, then data leakage may be possible due to malicious software installed in thick client mobile devices. In this paper, we present Data Firewall, a security framework to manage and protect security-sensitive data in thick client mobile devices. Data Firewall consists of three components: Virtual Machine (VM) image management, client VM integrity attestation, and key management for Protected Storage. There are two types of execution VMs managed by Data Firewall: Normal VM and Secure VM. In Normal VM, a user can execute any applications installed in the laptop in the same manner as before. A user can access security-sensitive data only in the Secure VM, for which the integrity should be checked prior to access being granted. All the security-sensitive data are stored in the space called Protected Storage for which the access keys are managed by Data Firewall. Key management and exchange between client and server are handled via Trusted Platform Module (TPM) in the framework. We have analyzed the security characteristics and built a prototype to show the performance overhead of the proposed framework.

• 한국컴퓨터정보학회논문지
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• 제19권2호
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• pp.125-132
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• 2014

본 논문에서는 저가의 웹 카메라를 사용하여 마커 없이 손끝과 붓을 트래킹 하는 시스템을 제시한다. 트래킹 시스템은 CUDA를 사용하여 병렬처리를 적용했다. 이 트래킹 시스템은 노트북이나 데스크탑과 같은 환경에서 수행이 가능하고, 실시간 애플리케이션에 사용 가능한 성능을 가진다. 또한 본 논문에서는 사적인 수성 사인펜 드로잉 모델을 제시하고 구현된 결과를 보여준다. 제안하는 시스템은 손끝과 붓을 트래킹 하는 저가의 실시간 트래킹 시스템으로 사실적 드로잉 애플리케이션과 연동하여 미래 최첨단 교육 환경 구축의 테스트베드로의 활용을 기대한다.

• 서비스연구
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• 제6권3호
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• pp.79-90
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• 2016

무선 인터넷 서비스는 모든 산업을 지원하는 중요한 요소 중에 하나로 자리 잡게 되었다. 어디에서나 무선 인터넷 연결을 통해 노트북을 연결하거나 스마트폰 등을 연결해 사용하는 일이 잦아지면서 그에 따른 해킹 위험도 증가하고 있다. 인터넷 공유기의 DNS 주소 변조를 통한 정보유출 사고를 비롯하여 무선 공유기를 통한 해킹위협은 존재한다. 본 논문에서는 무선 랜에서의 전반적인 취약점을 이용한 해킹 기술들을 다룬다. WEP 암호화 알고리즘과 이를 개선한 암호화 알고리즘을 통하여 무선 랜 보안의 필요성에 대하여 분석하였다. 또한 무선 취약점을 이용한 해킹 기술인 WEP Crack, DoS 공격, DNS Spoofing에서 해킹 기술들을 다루며, 이러한 해킹에 대하여 대응 방안을 제시하였다.