• The Journal of Engineering Geology
• /
• v.25 no.1
• /
• pp.131-148
• /
• 2015

The purpose of this study is to analyze and compare the heat transfer efficiency of using copper pipe, stainless pipe and traditional PE pipe commonly used for geothermal heat exchanger, with aims at seeking improved methods. In addition, the varying efficiency of heat transfer from ground heat and groundwater heat was assessed and its applicability was discussed. Design parameters for empirical field study were derived by controlling flow rate, velocity and caliber of pipes of the heat exchanger after the thermal efficiency of the heat exchanger material was evaluated. The heat exchange efficiency and effective thermal conductivity were measured with changing pattern through field thermal efficiency and thermal response test. Experimental results show that the metal material showed higher heat transfer efficiency than the PE pipe. Although the heat transfer efficiency was not high with the increase of the pipe diameter in the flow rate, it was high with the increase of the pipe diameter in the velocity.

• Journal of Satellite, Information and Communications
• /
• v.1 no.2
• /
• pp.32-37
• /
• 2006

ETRI has been developing the Ka-band Antenna subsystem for COMS(Communications, Ocean, and Meteorological Satellite) which will be launched at the end of 2008. The antenna subsystem employs the two parts: East Panel and West panel of spacecraft. ETRI in cooperation with domestic companies are under design phase for the antenna subsystem development. This paper focuses in the Ka-band reflector pointing error analysis to verify the antenna subsystem performance specification, especially EOC gain variation etc. The analysis performed is that induced by reflector surface deformation as a result of thermo elastic distortion. Beam pattern variations are verified by the use TICRA

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.1
• /
• pp.103-111
• /
• 2010

The study was conducted to examine the possible psychological difference in visual preference for natural landscape depending on the residence characteristic of the visitors, with the aim to use as the reference when creating space for natural landscape. Visitors were classified into three groups, namely, urban, suburban, and rural residents, and their preferred type of landscape was surveyed. The result showed that regardless of their residence the highest preference was to the place with superior natural landscape features, and among such features the common preference was toward the landscapes with horizons and those with animals. Urban and suburban residents showed similar preference pattern, and there was artistically significant difference with rural residents. In this respect, the difference in preference for natural landscapes could be induced between urban and rural residents. Rural residents had similar preference with urban residents in that they both preferred the place with superior natural landscape features, but differed in that the former had significantly higher preference toward the landscapes that have mixed artificial elements. From the above research, the following conclusions can be inferred:for regions that need to create natural landscapes, differentiated visual landscape plans and strategies need to be established taking into account, inter alia, the natural richness of the neighborhood natural environment; for regions that need to conserve and manage natural environment and landscapes, the measures to adjust the natural landscape management plans need to be established taking into account the neighborhood environment of the protected areas and the number of visitors to the region.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.15 no.3
• /
• pp.41-50
• /
• 2009

Studies about architectural planning for elderly residences have been carried out to examine various factors including the unit plan, site planning, and size planning. However, no studies have been undertaken that focus on the residents' daily life patterns. This study offers the design guidelines to support the daily life patterns of the elderly through the planning of elderly housing. For this study, elderly residents in Tokyo, Yokohama etc. in Japan were interviewed and surveyed. The results indicate that the changes to the daily life patterns of the residents living in elderly housing are the reduction of household, the increase of free time, and the change of social relationships. The elderly want to utilize their free time and focus on their social relationships. However, the elderly residences that we surveyed pay no consideration to social spaces and programs for their residents except for the cafeteria. To support the daily life patterns of the elderly, elderly housing should set a high value on the location, shared spaces, and unit plans of the residences in order to consider the personal diversity of the residents. Accessibility to public transportation systems and facilities should to be considered in the initial location planning. The revitalization of the public spaces should to be considered during the architectural planning stage. Considerations of personal taste during the unit planning stage are also necessary.

• Journal of the Korean Society for Heat Treatment
• /
• v.19 no.1
• /
• pp.30-36
• /
• 2006

Fretting fatigue behavior of SCM420 steel commonly used in the automotive industry for structural applications was investigated in this study. In addition, the effect of bridge pad on the fretting fatigue test was evaluated from different pad materials and following conclusions were drawn. Simple fatigue limit of SCM 420 steel was determined to be 350 MPa while this value was 225 MPa and 285.5 MPa with SCM420H and with SM45C pad, respectively. Reduction in fatigue limit was, thus found to be 35.7% and 17.9% with SCM 420H pad and SM45C pad, respectively. Results of fracture surface observation revealed that typical striation pattern of fatigue failure existed as well as dimpled and cleavage frature appearance was found in final fractured region. From the EDS compositional analysis, test sample and pad part all had high signals for oxygen and iron, suggesting that worn particles might be iron oxide, although exact chemical composition has to be confirmed. Considerable reduction in fatigue life was apparent in SCM 420 steel under fretting fatigue against simple fatigue. Such reduced fatigue life by fretting damage should be considered as an important factor not only in the viewpoint of repairing but also inevitably in the design stage of structural components.

• Journal of Internet Computing and Services
• /
• v.5 no.4
• /
• pp.63-76
• /
• 2004

For efficient design and operation of a communication network, precise simulation of network characteristics is essential. This issue has been the focus of research by several groups. In this study, we first modeled the HTTP traffic which would be employed on simulation on the level of application using the real collected traffic data. There are two different viewpoints on the characteristics of web traffic pattern, Poisson distribution and self-similar characteristics. In our study, the results show that web traffic characteristics do not depend on only one type of distribution, but the traffic can be modeled as composition of these depending on the size of response of Web server. This implicates that the web traffic can be modeled as the combination of two characteristics. We also found that the characteristics of Web traffic rely on the properties of web servers. This result was deployed as a traffic generator in implementing the network simulator (NetDAS).

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.12
• /
• pp.683-695
• /
• 2007

NAND flash memory-based file systems cannot store their system-related information in the file system due to wear-leveling of NAND flash memory. This forces NAND flash memory-based file systems to scan the whole flash memory during their mounts. The mount time usually increases linearly according to the size of and the usage pattern of the flash memory. NAND flash memory has been widely used as the storage medium of mobile devices. Due to the fact that mobile devices have unstable power supply, the file system for NAND flash memory requires stable recovery mechanism from power failure. In this paper, we present design and implementation of a new NAND flash memory-based file system that provides fast mount and enhanced stability. Our file system mounts 19 times faster than JFFS2's and 2 times faster than YAFFS's. The stability of our file system is also shown to be equivalent to that of JFFS2.

• The Journal of the Korea Contents Association
• /
• v.14 no.2
• /
• pp.387-395
• /
• 2014

The authors reviewed research related to nursing organizational culture in order to determine the direction for future research, as well as the current status of nursing organizational culture. Research that analyzed nursing organizational culture were selected from journal articles in Korea and were reviewed. A total of 30 articles were collected. The number of studies on nursing organizational culture has shown a rapid increase since the late 1990s. Most research studies used a non-experimental design. The most frequently used organizational culture model and instrument was the competing values model defining culture pattern, which consists of relation-oriented, innovation-oriented, hierarch-oriented, and task-oriented culture. Other factors showing correlation with nursing organizational culture included job satisfaction, effectiveness, and so on. These results will be used to provide basic data for nursing leaders. In Korea, the next phase of research on organizational culture will require use of various approaches and research methods.

• 한국연소학회:학술대회논문집
• /
• 2002.06a
• /
• pp.85-94
• /
• 2002

Computational flow dynamics(CFD) has been frequently applied to the waste incinerators to understand the flow performance for various design and operating parameters. Though it needs many simplifications and complicated flow models, the reasonability of its results is not fully evaluated. For example, the inlet condition is calculated from an arbitrarily assumed properties of combustion gas release from the waste bed, since the combustion in the bed is difficult to be predicted. In this study, the computational modeling and calculation procedures of CFD for the grate type waste incinerator were evaluated using comparative simulations. Though the assumption method on the generation of the combustion gas directly affected the temperature and gas species concentrations, the overall flow pattern was dominated by the secondary air jets. The gaseous reaction could be included by assuming the release of the products of incomplete combusion from the bed. However, the reaction effficiency cannot not be directly evaluated from the species concentration, since it is not possible to simulate the actual co-existence of fuel rich or oxygen rich puffs over the bed. In predicting the turbulence, the higher order model, such as Reynolds stress model, gave difference shape of local recirculation zones, but similar results was acquired from the standard $k-{\varepsilon}$ model. Introducing radiation model was required for accurate temperature prediction, but it also caused heat imbalance due to the fixed temperature of the inlet, i.e. the waste bed. Thus, the computational modeling procedures on incinerators and the analysis of the predicted results should be progressed carefully. Though not validated experimentally, current simulation method is capable of comparative evaluation on the flow-related parameters such as the furnace shape and secondary air injection using identical inlet conditions. Quantitative analysis using measures of the residence time and mixing is essential to compare the flow performance efficiently.

• The Journal of the Korea Contents Association
• /
• v.17 no.2
• /
• pp.96-104
• /
• 2017

As new smart devices are evolved into the intelligent agent who can reflect user intention and use context, user experience design for easy and convenient usability becomes a core competitive edge. Under the assumption that human centered natural interaction is necessary for the optimal smart TV experience, this study explores the types of voice interaction which are peculiar to TV watching context. In order to build a model for the users to naturally interact with Smart TV, conversation patterns were collected by requesting key features of Smart TV to intelligent agent. Collected sentences were applied to CfA model and classified by responses to activate features. The classified conversation patterns were divided into feature activation and information search. This study has identified that CfC1 occurred when voice interaction between Smart TV and users was vague and CfC2 occurred when the requests were complex or conditional. In conclusion, Simple Request Type is the most efficient model and voice interaction is more appropriate to use to clarify users' vague requests.