• 한국생산제조학회지
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• 제8권1호
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• pp.89-99
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• 1999

The automatic design of shell & tube type oil cooler can be used in real industrial environments. Since the automatic design system is intended to be used in small companies, it is designed to be operated well under environments of CAD package in the personal computer. It has adopted GUI in design system, and has employed DCl language. Design parameters to be considered in the design stage of shell and tube type oil cooler are type of oil cooler, outer diameter, thickness, length of tube, tube arrangement, tube pitch, flow rate, inlet and outlet temperature, physical properties, premissive pressure loss on both sides, type of baffle plate, baffle plate cutting ratio, clearance between baffle plate outer diameter and shell inner diameter and clearance between baffle plate holes. As a result, the automatic design system of shell & tube type oil cooler is constructed by the environment of CAD software using LISP. We have built database of design data for various kinds of shell & tube type oil coolers. The automatic design system have been assessed and compared with existing specification of design. Good agreement with Handbook of heat exchanger and design dta of real industrial environments has been found.

• Journal of Computing Science and Engineering
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• 제9권3호
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• pp.155-162
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• 2015

The last decade has seen a rapid growth in the use of mobile devices all over the world. With an increasing use of mobile devices, mobile applications are becoming more diverse and complex, demanding more computational resources. However, mobile devices are typically resource-limited (i.e., a slower-speed CPU, a smaller memory) due to a variety of reasons. Mobile users will be capable of running applications with heavy computation if they can offload some of their computations to other places, such as a desktop or server machines. However, mobile users are typically subject to dynamically changing network environments, particularly, due to user mobility. This makes it hard to choose good offloading decisions in mobile environments. In general, users' mobility can provide some hints for upcoming changes to network environments. Motivated by this, we propose a mobility model of each individual user taking advantage of the regularity of his/her mobility pattern, and develop an offloading decision-making technique based on the mobility model. We evaluate our technique through trace-based simulation with real log data traces from 14 Android users. Our evaluation results show that the proposed technique can help boost the performance of mobile devices in terms of response time and energy consumption, when users are highly mobile.

• 한국정밀공학회지
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• 제26권10호
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• pp.32-39
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• 2009

Most mobile devices provide limited input interfaces in order to maximize the mobility and the portability. In this paper, the author proposes a small cubic-shaped tangible input interface which tracks the location, the direction, and the velocity using MEMS sensor technology to overcome the physical limitations of the poor input devices in mobile computing environments. As the preliminary phase for implementing the proposed tangible input interface, the prototype design and implementation methods are described in this paper. Various experiments such as menu manipulation, 3-dimensional contents control, and sensor data visualization have been performed in order to verify the validity of the proposed interface. The proposed tangible device enables direct and intuitive manipulation. It is obvious that the mobile computing will be more widespread and various kinds of new contents will emerge in near future. The proposed interface can be successfully employed for the new contents services that cannot be easily implemented because of the limitation of current input devices. It is also obvious that this kind of interface will be a critical component for future mobile communication environments. The proposed tangible interface will be further improved to be applied to various contents manipulation including 2D/3D games.

• 대한수학교육학회지:학교수학
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• 제11권2호
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• pp.281-299
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• 2009

본 논문에서는 동적조작 환경 속에서 이루어지는 물리적 실험을 도구로 선택하여 발명되고 있는 과정으로서의 수학을 학생들이 접할 수 있도록 1) 정의 도입 방식을 변화시켜 의미 있는 수학적 정의를 만들어내는 2) 시각화를 통한 연속성 사고 능력을 강화하는 3) 발견과 탐구를 통하여 수학을 만들어내는 4) 문제를 제기하고 일반화하는 능력을 강화하는 사례들을 제시하고 분석함으로써 수학교과과정에 어떻게 동적조작 환경을 융합시킬 수 있는가를 보였다. 이러한 교수-학습 환경 하에서 발생할 수 있는 문제점을 분석하고, 이러한 문제점을 해결하기 위한 교사의 역할에 대해 논하였다.

• 정보처리학회논문지C
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• 제12C권2호
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• pp.261-266
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• 2005

본 논문에서는 두 개의 시스템을 제안한다. 하나는 홈 네트워크 환경에서 각종 디지털 정보가전들을 효율적으로 연결/제어할 수 있는 홈 게이트웨이이다. 다른 하나는 흠 게이트웨이의 물리적인 한계를 극복하기 위한 관리 서버이다. 홈 게이트웨이는 이더넷/ADSL과 같은 TCP/IP 네트워킹 기능을 지원하며, HomePNA, IEEE1394, PLC와 같은 홈 네트워크 기능, PSTN/SLT, VoIP, 비디오 통신과 같은 통신기능을 구현하였으며, 향후 디지털 홈 환경에서의 핵심 네트워크 장비가 될 것이다. 관리 서버는 한 지역 내에 설치된 흠 게이트웨이와 이와 연동된 각 가정 내의 다양한 디지털 정보가전 및 HA(Home Automation) 기기들을 통합 관리/제어하는 특정 서버이다.

• 전자통신동향분석
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• 제36권5호
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• pp.32-41
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• 2021

As the COVID-19 crisis continues, working environments and lifestyles have been changed unexpectedly, therefore the importance of mental health in the working environments has been highlighted. When the workers' mental health deteriorates, there will be personal losses but also human resources losses caused productivity decrements of the company or the organization. Many researchers have been tried to solve these issues with the help of ICT technologies such as wearable devices. Most wearable healthcare devices have been designed to detect the physiological status of users and collect the physical activities of users, and their applications are gradually expanding. Those devices may be good candidates to prevent loss of human resources from working environments especially under the COVID-19 situation by continuously monitoring mental health status in connection with mobile devices and managing the mental health on their own by combining mental well-being with support solutions. In this paper, the development trend of mental health measurement and mental well-being support technologies is analyzed, and development prospects are examined.

• 한국태양에너지학회 논문집
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• 제38권6호
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• pp.65-72
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• 2018

Since data-driven building technologies have been widely applied to building energy systems, the accuracy of building sensors has more impacts on the building performance and system performance analysis. Various building sensors, however, can have typical errors including a random error (noise) and a systematic error (bias). The systematic error is indicated by the difference between the mean of measurements and their true value. It may occur due to the sensor's physical condition, measured phenomena, working environments inside the systems. Unfortunately, a conventional calibration method has limitations in calibrating the systematic errors because of the difference between working environments and calibration conditions. In such situations, a novel sensor calibration method is needed to handle various sensor errors, especially for systematic errors, in building energy systems having various thermodynamic environments. This study proposes a building sensor calibration method named Virtual In-situ Calibration (VIC) and shows how it is applied into a real building system and how it solves the sensor errors.

• 정보보호학회논문지
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• 제16권2호
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• pp.3-12
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• 2006

모바일 디바이스, PDA, 센서들의 확산은 실생활 공간이 지능적이고 향상된 서비스를 제공하는 스마트 공간으로 전환되는 유비쿼터스 컴퓨팅 환경이 구축될 수 있도록 하였다. 그러나 모바일 디바이스, PDA, 센서들과 같은 다양한 유비쿼터스 디바이스들의 초기 설계 단계부터 프라이버시 문제를 고려하지 않는다면 유비쿼터스 감시체제가 구축될 위험성이 있다. 또한 유비쿼터스 컴퓨팅 환경에서의 다양한 디바이스들은 대체로 컴퓨팅 연산 능력이 적기 때문에, 공개키 기반의 암호기술을 적용하는 것은 부적절할 수 있다. 본 논문에서는 유비쿼터스 컴퓨팅 환경에서의 사용자 프라이버시를 위하여 익명성이 보장되고, 컴퓨팅 연산 능력이 적은 디바이스를 위한 효율적인 사용자 인증 및 키 동의 프로토콜을 제안한다.

• ETRI Journal
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• 제37권2호
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• pp.369-379
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• 2015

Fault management of virtualized network environments using user-driven network provisioning systems (NPSs) is crucial for guaranteeing seamless virtual network services irrespective of physical infrastructure impairment. The network service interface (NSI) of the Open Grid Forum reflects the need for a common standard management API for the reservation and provisioning of user-driven virtual circuits (VCs) across global networks. NSI-based NPSs (that is, network service agents) can be used to compose user-driven VCs for mission-critical applications in a dynamic multi-domain. In this article, we first attempt to outline the design issues and challenges faced when attempting to provide mission-critical applications using dynamic VCs with a protection that is both user-driven and trustworthy in a dynamic multi-domain environment, to motivate work in this area of research. We also survey representative works that address inter-domain VC protection and qualitatively evaluate them and current NSI against the issues and challenges.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.805-821
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• 2011

Wireless Sensor Networks (WSNs) are rapidly emerging because of their potential applications available in military and civilian environments. Due to unattended and hostile deployment environments, shared wireless links, and inherent resource constraints, providing high level security services is challenging in WSNs. In this paper, we revisit various security attack models and analyze them by using a well-known standard notation, Unified Modeling Language (UML). We provide a set of UML collaboration diagram and sequence diagrams of attack models witnessed in different network layers: physical, data/link, network, and transport. The proposed UML-based analysis not only can facilitate understanding of attack strategies, but can also provide a deep insight into designing/developing countermeasures in WSNs.