• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1361-1364
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• 1990

In order to tackle global environmental problems such as destruction of the ozone layer or climatic changes due to atmospheric temperature increase, the acquisition of plentiful and precise data is necessary. Therefore, a means of conducting long-lasting high-resolution measurements over broad areas is required. A feasibility study has been made on a high altitude (20km), super-pressured helium-filled PLTA (Powered Ligher-than-Air) vehicle as an ideal platform for environmental observation. It has a long service life and carries a larger payload than an artificial satellite. This PLTA platform uses an electric propulsion system to maintain position in space against wind currents. The thruster is driven by solar power acquired from solar cells. For night use, solar energy is stored in regenerative fuel cells. This study focuses on energy balance and structural analysis of the hull and platform. The platform is capable of conducting high resolution remote sensing as well as having the capability to serve as a telecommunications relay. The platform could replace a number of ground-based telecommunications relay facilities, guaranteeing sufficient radio frequency intensity to secure good quality telecommunication transmittal. The altitude at which the platform resides has the lowest wind flow in the lower stratosphere, and permits viewing from the ground within a 1,000km range. Because this altitude is much lower than that required of an artificial satellite, the measuring resolution is a couple of thousand times higher than with artificial satellites. The platform can also be used to chase typhoons and observe them from their sources in tropical regions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.9
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• pp.4144-4165
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• 2018

Software-defined networking (SDN) has emerged as a promising technology for network programmability and experiments. In this work, we focus on virtual network embedding in multiple controllers SDN network. In SDN virtualization environment, virtual SDN networks (vSDNs) operate on the shared substrate network and managed by their each controller, the placement and load of controllers affect vSDN embedding process. We consider controller placement, vSDN embedding, controller adjustment as a joint problem, together considering different quality of service (QoS) requirement for users, formulate the problem into mathematical models to minimize the average time delay of control paths, the load imbalance degree of controllers and embedding cost. We propose a heuristic method which places controllers and partitions control domains according to substrate SDN network, embeds different QoS constraint vSDN requests by corresponding algorithms, and migrates switches between control domains to realize load balance of controllers. The simulation results show that the proposed method can satisfy different QoS requirement of tenants, keep load balance between controllers, and work well in the acceptance ratio and revenue to cost ratio for vSDN embedding.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.333-344
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• 2020

This research has four specific objectives: (1) identifying factors that affect customer satisfaction with less than container load (LCL) cargo services of logistics companies in HoChiMinh City (HCMC), (2) measuring the level of impact of the factors, (3) testing the difference in satisfaction among groups of customers with different characteristics in terms of type of business and time of using LCL cargo services, and (4) proposing some management implications to improve the quality of LCL cargo services. Researchers interviewed 210 customers who enjoyed the LCL cargo service in HCMC for at least the last six months, using the convenient sampling method. SPSS 20 was used to analyze the reliability of the scale through the Cronbach's alpha coefficient, then exploratory factor analysis and multiple linear regression analysis were used. The results identified the six factors that influence positively customer satisfaction of LCL cargo services of logistics companies in HCMC, by decreasing importance: service process, image, resource, price, management, and outcomes. The results show that there is no difference in customer satisfaction with LCL cargo services by types of business as well as time of using services. The research suggests some implications for the management of logistics companies in HCMC to enhance customer satisfaction.

• Safety and Health at Work
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• v.12 no.4
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• pp.462-470
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• 2021

Background: Fatigue is pervasive, under-reported, and potentially deadly where flight operations are concerned. The aviation industry appears to lack a standardized, practical, and easily replicable protocol for fatigue risk assessment which can be consistently applied across operators. Aim: Our paper sought to present a framework, supported by real-world data with subjective and objective parameters, to monitor aircrew fatigue and performance, and to determine the safe crew configuration for commercial airline operations. Methods: Our protocol identified risk factors for fatigue-induced performance degradation as triggers for fatigue risk and performance assessment. Using both subjective and objective measurements of sleep, fatigue, and performance in the form of instruments such as the Karolinska Sleepiness Scale, Samn-Perelli Crew Status Check, Psychomotor Vigilance Task, sleep logs, and a wearable actigraph for sleep log correlation and sleep duration and quality charting, a workflow flagging fatigue-prone flight operations for risk mitigation was developed and trialed. Results: In an operational study aimed at occupational assessment of fatigue and performance in airline pilots on a three-men crew versus a four-men crew for a long-haul flight, we affirmed the technical feasibility of our proposed framework and approach, the validity of the battery of assessment instruments, and the meaningful interpretation of fatigue and work performance indicators to enable the formulation of safe work recommendations. Conclusion: A standardized occupational assessment protocol like ours is useful to achieve consistency and objectivity in the occupational assessment of fatigue and work performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.70-76
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• 2013

Because increased food delivery service and quick delivery service using motorcycle, registration numbers of motorcycles were sharply increased and it could contribute on worsening air quality. In this study, two models(50cc, 125cc) of motorcycle were tested by using three types of engine oil. Two motorcycles were tested with CVS-40 mode for emission characteristics such as CO, THC, NOx, Elemental Carbon(EC), Organic Carbon(OC), sulfate, soot and SOF(soluble organic fraction). Result of according to three types of lubricants which included phosphorus, sulfate ash impacted to particle matters so "C" lubricants is more higher PM than "A", "B" lubricants in this research.

• Journal of Families and Better Life
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• v.16 no.4
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• pp.69-82
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• 1998

As a way to serve housing information providing on internet will be a useful method in the near future in Korea. This study was planned to review the housing information on internet network which provided by U. S. .University CES(cooperative extension service) Comparative analysis was used as a Research method in terms of contents and items about housing information on internet provided by U. S. university CES during two weeks each in August 1997 and July 1998. Findings are as follows; Universities providing housing information and information items had been remarkably increased during one year since August 1997. Most of housing informations except one university CES were free to use in 1997 but three university CES among 12 universities showed only the title of items with charge amounts in 1998. Informations about 'Housing Management' and 'Environment' items were the large parts of the housing information in 1997. In 1998. 'Environment' items were remarkably increased. Items bout insects and mildew removing were large portion of the 'Housing Management'. Items about energy saving water and air quality were large portion of the 'Environment' These findings will be useful to develop items of housing information on internet network with Korean language which should be compensated by the survey research.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.606-609
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• 2015

Lawful Interception (LI)이란 합법적인 형태의 통신내용 및 관련 정보의 수집활동을 말한다. 최근의 4G LTE 기반의 이 기종 통신망에서의 합법적 감청은 전통적인 유선 및 3G 네트워크 중심의 감청기법 이외의 새로운 기법과 표준이 필요한 실정이다. 특히, LTE와 같이 User Equipment (UE)가 네트워크상에서 핸드오버를 통해 자유롭게 이동하거나, 3G와 같은 이 기종 망에서의 연결을 포함한 다른 사업자의 새로운 지역에서의 네트워크 연결이 보장되는 형태의 환경에서의 연속적 감청을 보장하는 것은 합법적 감청분야의 중요한 이슈중의 하나이다. 따라서, 본 논문에서는 국내의 4G-LTE망을 중심으로 기존의 3G 망을 자유롭게 이동하는 네트워크 도메인과 IMS/SIP 기반의 서버의 연속성을 보장하는 서비스 도메인 영역에서의 합법적 감청 기법을 제안한다. 본 논문에서 제안하는 기법은 이 기종 무선망과 유선망이 혼재된 네트워크에서의 IMS/SIP 기반 서비스의 이동성을 감지하여 합법적 감청의 연속성을 보장하기 위한 기법을 포함하고 있다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.10
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• pp.679-686
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• 2010

A proprietary device is adopted to break out the membrane of cell in the rigid polyurethane foam. As it is known, the membrane of cell is hardly tearing-off thoroughly in a mechanical way due to both its elastic characteristic and micro sized pores. In this study, a novel experimental approach is introduced to burst out all gases inside the cells of the rigid polyurethane foam by abrasively grinding micro-cells completely into fine powder. The biggest advantage of this approach is to be capable of releasing all gases out from the cell even in the micro pores. As clearly reflected from the repeatability, the accuracy of the result is highly improved and high confidence in the data sets as well. For the measurements of not only gas composition but partial pressure for each gas simultaneously as well, a precision gas mass spectrometer is used in-line directly to the abrasive grinding device. To control the starting point of the polyurethane foam, all samples were prepared on site in the laboratory. Manufactured time is one of the most critical factors in characterization of cell gas composition because it is known that one of gas composition, especially, carbon dioxide, is diffused out dramatically in a short period of time as soon as it is foamed.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.130-134
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• 2007

This study was carry out to investigate the effect of supplemental lighting on the growth and flowering of Rosa hybrida 'Nobles' in winter. Supplemental lighting was treated during 5 hours at night with sodium lamp and fluorescent lamp, and cut flowers harvested 2 times for the experimental period. After supplemental lighting, air temperature and slab temperature in glasshouse was higher in sodium lamp treatment than control. Realtive humidity was low in sodium lamp treatment. Total nitrogen phosphate, potassium, calcium, and magnesium contents of stem in sodium lamp treatment were higher compare to the other treatment. In sodium lamp treatment, the potassium and magnesium content of leaf in control were lower than the others. Chlorophyll content was not different by source of lighting. Stem length and diameter was longer in sodium lamp treatment. In two times, the yield was highest in sodium lamp treatment. Therefore, supplemental lighting with sodium lamp in winter season was recommended for improving the yield and quality in cut rose 'Nobles'.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.4
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• pp.485-493
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• 2009

The u-City offers diverse u-services, which are integrated with information and GIS technologies, by utilizing an integrated management platform for controlling the city efficiently, increasing convenience of city lift, and improving the quality of lives. An urban control system is a core element of the u-City to connect organically and expand all kinds of information through various u-interfaces. This study presents the implementation of a GIS service module based on the urban control system for the efficient development of u-services, which contributed to the successful execution of GIS service scenarios that include processes of unexpected events, air pollution monitoring, and emergences. The results of the study can be used as basic data for the design and operation of practical u-City services.