• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.4
• /
• pp.1076-1089
• /
• 2012

Home automation networks are good environments for merging sensor networks and consumer electronics technologies. It is very important to reduce the energy consumption of each sensor node because sensor nodes operate with limited power based on a battery that cannot be easily replaced. One of the primary mechanisms for achieving low energy operation in energy-constrained wireless sensor networks is the duty-cycle operation, but this operation has several problems. For example, unnecessary energy consumption occurs during synchronization between transmission schedules and sleep schedules. In addition, a low duty-cycle usually causes more performance degradation, if the network becomes congested. Therefore, an appropriate control scheme is required to solve these problems. In this paper, we propose UDC (Unsynchronized Duty-cycle Control), which prevents energy waste caused by unnecessary preamble transmission and avoids congestion using duty-cycle adjustment. In addition, the scheme adjusts the starting point of the duty-cycle in order to reduce sleep delay. Our simulation results show that UDC improves the reliability and energy efficiency while reducing the end-to-end delay of the unsynchronized duty-cycled MAC (Media Access Control) protocol in sensor-based home automation networks.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11b
• /
• pp.403-405
• /
• 2005

IT산업이 발달하고 고도화 됨에 따라 소프트웨어가 차지하는 비중이 점차 높아지고 있다. 국내의 경우 정보통신부가 2001년 하반기부터 소프트웨어업체 사업자 평가제도를 도입/시행 중으로 이에 따라 소프트웨어 개발/관리 조직들은 소프트웨어 품질 평가 심사모형인 5티CE 및 CMM의 등급 인증획득과 등급 상향을 위해 큰 관심과 노력을 기울이고 있다. 그러나 이중 SPICE 인증의 신뢰성이나 효과에 대한 충분한 검증 및 연구가 이루어 지고 있지 않아, 본 논문에서는 특히 SPICE 등급을 인증받은 조직이 비인증 조직과 비교하여 품질 및 성과에 차이를 보이는지 조사하였다. 자료수집의 한계에도 불구하고 본 논문을 통해 SPICE 인증 조직이 비인증 조직보다. 프로젝트 품질 성과 및 조직성과 측면에서 어떤 개선효과를 거두고 있는지 특히 피심사부서의 담당관련자들을 중심으로 조사, 분석하여 그 결과를 요약하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2008.10b
• /
• pp.316-321
• /
• 2008

In the present emerging global economy, as the focus is shifted from manufacturing to service sector, the efficiency of service operations is crucial for the county's sustainable growth and development. As one of the fastest growing service sector industries in South Korea, the call center has become an inevitable part of customer service for most companies. Despite of the strategic importance of the call center, there has been no empirical study on the efficiency of call center service operations in the literature. The main purpose of this study is to evaluate the technical efficiency of call center services so as to not only identify the current status of call center service operations, but also suggest ways to improve service operations efficiency. For this purpose, we apply a non-parametric efficiency measurement method, DEA (Data Envelopment Analysis), to domestic call centers in order to compare their relative efficiency. Based on DEA evaluations, we provided specific directions for the inefficient call centers to possibly improve their operation efficiencies. It is expected that the measurement methods suggested in this study can be applied to various issues such as service KS certification, service operations management, and the productivity analysis of service personnel.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.603-609
• /
• 2008

Nowadays, double-system of TFM(Track-side Functional Modules) developed instead of single-system in use of high speed line to acquisition more availability. Safety Law for Railroad recommend to quality certification of development and general railway machines. It is important to select metrics which form the bases for testing software products. A number of package software development part do not open source cords, so testing external characteristic vectors having relationship with metrics. In this paper, review the process for the TFM Point Modules, Universal Modules and Switchers, think about the test methode of circuit boards output performance by using TFM tester and Simulators.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2017.11a
• /
• pp.1173-1175
• /
• 2017

This paper proposes a system for convenient remote control and management of the lockers with a smart phone. The key features of the proposed system are as follows. First, we connect the lockers to the server and then use the authentication procedure to open and close their lockers. Second, we create instant lockers to increase convenience for users who need to use casual necessities. Unlike traditional analog methods, we finally develop certification procedures. Particularly, log data are better secured than traditional ones. The performance assessment of the proposed system is simulated by producing a dummy model. We will show that the proposed system could effectively support opening and closing the lockers using smart phones.

• KIEAE Journal
• /
• v.12 no.6
• /
• pp.29-38
• /
• 2012

The current building energy efficiency rating certification regulation on apartment houses evaluates only the saving rate of energy consumed during operation, i.e. use, of a building, but doesn't consider the energy consumptions and environmental load($CO_2$) emissions occurring during the whole lifetime of a building. So this study calculated the energy consumptions and environmental load emissions occurring during the whole lifetime of a building, selected reference schemes and alternative items by design variables to present a design draft considering energy efficiency and environmental performance, and evaluated the total cost by combining and calculating its direct cost(material and heating cost) and indirect cost(environmental cost), for an existing apartment house as an evaluation object. As a result of analysis, the change of heating cost by alternative items of design variables showed a 4~8% change rate compared to the reference scheme, and the material cost of design variable 7 showed a maximum 4.4 times change rate in the alternative plan 6 compared to the reference scheme. The environmental cost showed a similar change rate to the material cost change rate in general, but showed a similar environmental cost change rate to the heating cost change rate in case of design variables 4-1, 4-2, 7.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.11
• /
• pp.2171-2175
• /
• 2011

The objective of this paper is to discuss technologies on assessing reliability of arc detectors by composing a system that generates and simulates occurrence of arc caused by loss of contact between pantographs and contact wires in a laboratory condition. In order to establish the arc simulator, a device that generates light having the bandwidth of arcs that occur between carbon-metal. The simulator was designed under conditions of EN 50317 and simulations were conducted using the developed device. According to the results, it was possible to conduct certification tests following regulations of international standards and the precision of the simulator was satisfactory. The proposed arc detector assessment system is expected to enhance precision of current collection quality performance assessment methods at high-speed lines and conventional lines while being referred as fundamental technologies for development of detectors suiting international conditions.

• Journal of the Korean Society of Safety
• /
• v.28 no.3
• /
• pp.74-79
• /
• 2013

As the feature of fire, it is hard for deep-seated fire to spread to the deeper site, and it also has danger for being re-ignited cause of recontacting with oxygen after being put off. Now it is ruled in the certification criteria of wetting agent used for extinguishing deep-seated fire that the criteria for surface tension is below 33[mN/m] in Korea. For figuring out how much water for fire-fighiting can permeate into combustibles, in this research, the permeating performance is analyzed by measuring the speed of permeating and transmission quantity released after that, by pouring solution whose surface tension is changed by adjusting concentration of surfactant BDG(Butyl Di Glycol) in column From this result, it is can be determined that transmission quantity becomes less and wet area goes wider as surface tension is lower, and it is also able to be analyzed as quantity of absorbed liquid and wet area is increased because fluid permeates into the core.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.26 no.1
• /
• pp.29-37
• /
• 2020

Purpose: The purpose of the research is to find difficulty levels of LEED credits in each LEED level based on credits achievement in order to find important of LEED-HC credits to gain LEED-HC. Methods: The individual credits of LEED-HC v.2009 scorecards from USGBC website are analyzed. With achieved scores rate of LEED credits per each Level, all credits are reassembled in 4 different ranges (A~D); easy (A), easy-moderate (B), moderate-hard (C) and hard (D) to achieve scores. Results: 1) Achieved point rate in LEED-HC specific credits are low. These credits need to be reviewed carefully. 2) In 88 projects, 37 projects are gained Silver level which is more than projects in certification level. In order to encourage to gain LEED-HC level, Average Achieved rate to earn Certificate level needs to be risen. 3) Credits in range D rarely affect to gain platinum level. EAc1 (24 points) are critical to gain Silver and Gold level. However, EAc1 points are not effective to achieve Certificate level. Implications: This research will provide a fundamental back data to set up Korean Green building rating system for Healthcare.

• Nuclear Engineering and Technology
• /
• v.39 no.4
• /
• pp.287-298
• /
• 2007

As part of the $AP1000^{TM}$ pressurized water reactor design certification program, a series of integral systems tests of the nuclear steam supply system was performed at the APEX-1000 test facility at Oregon State University. These tests provided data necessary to validate Westinghouse safety analysis computer codes for AP1000 applications. In addition, the tests provided the opportunity to investigate the thermal-hydraulic phenomena expected to be important in AP1000 small-break loss of coolant accidents (SBLOCAs). The APEX-1000 facility is a 1/4-scale pressure and 1/4-scale height simulation of the AP1000 nuclear steam supply system and passive safety features. A series of eleven tests was performed in the APEX-1000 facility as part of a U.S. Department of Energy contract. In all, four SBLOCA tests representing a spectrum of break sizes and locations were simulated along with tests to study specific phenomena of interest. The focus of this paper is the SBLOCA tests. The key thermal-hydraulic phenomena simulated in the APEX-1000 tests, and the performance and interactions of the passive safety-related systems that can be investigated through the APEX-1000 facility, are emphasized. The APEX-1000 tests demonstrate that the AP1000 passive safety-related systems successfully combine to provide a continuous removal of core decay heat and the reactor core remains covered with considerable margin for all small-break LOCA events.