• Korean Journal of Social Welfare
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• v.69 no.3
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• pp.213-240
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• 2017

In the harsh period for young adults to prepare their successful life, this study aimed to understand the specific experiences of independence transition among homeless young adults. Also this article explored how their family perform as a supportive system for their independence. Using in depth interview materials of 19~39 aged 8 young homeless males, the research analyzed their family's weak support; no family members, no economic support and breaking relationship. As to occasion of independence, the participants sometimes experienced loss of house, evacuation by their family or runaway from their home. It was abrupt and unexpected leaving home. Also their process of independence was beyond their capacity that they suffered from instability job and destitute rather than continuous mental trauma and isolation. In the end they faced serious risky situations that they cannot manage without any help. The findings of this study suggest that quality of family relationship would be more important than economic capital from family and transition to adulthood of vulnerable young adults who don't have family support need much alternative supportive system and social capital.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.629-638
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• 2013

The Purpose of this study was to discover type of hope among korean middle-aged adult and to identify the major threads that structure various patterns of hope experienced by them. It is necessary to understand that experiencing hope of middle-aged adult experiencing numerous problems and loss at the transition of life. Q-methodology involves five steps in its approach. Collected Q-statements are 112 from 200 adults through 4 open-ended questions. Among them, 34 statements were decided as a Q-sample, The Q-sorting was carried out in 21 middle-aged adults. Three types of subjective experiences of hope emerged as : (1) Passive Wish Type, (2) Positive Pragmatic Hope Type, (3) Active Internal Value-Oriented Hope Type.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.47-53
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• 2007

The purpose of IEEE 802.16j is to extend coverage and to enhance throughput by using relay station additionally to conventional IEEE 802.16e . The cellular system experiences performance degradation at the cell edge due to pathloss, shadow and multipath fading. We can get advantage of spatial diversity gain by using relays more than two cooperatively in the IEEE 802.16j system. Cooperative relaying using space-time code provides better performance under multipath fading and has more robustness against the shadow fading than single relaying. In this paper, we investigate the performance of IEEE 802.16j using cooperative relaying by link level simulation. We also show that the cooperative relaying system achieves better performance than the conventional single relaying system. We apply realistic shadow model considering correlations between shadow fadings of different relaying paths. It is shown that the performance of the system depends highly on the spatial location of relay stations.

• Journal of Korean Elementary Science Education
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• v.39 no.1
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• pp.54-68
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• 2020

The purpose of this study is to investigate how elementary teachers perceive and practice using Visual Thinking (VT) in science classes. For this, we collected 161 VT teaching materials for science that uploaded on the elementary teacher's online communities, and analyzed the characteristics. Also we interviewed four elementary teachers who have used VT in science class. The results are as follows. First, VT teaching materials shared in teacher's online communities were most often used to review the science concepts that students learned. Most of the materials required 'remember' among the Cognitive Process, and most of them provided layouts for VT activities. Second, the participants were using VT materials to review the science concepts they learned, so that students remember them. Third, the participants were satisfied because of the beliefs of effects as follows: facilitating learning and reviewing what students had learned; increasing students' positive reactions and confidence; learning through the interation among learners; the formation of habits thinking visually; indirect experiences of science class; possibility of class corresponding to learner characteristics. Fourth, the participants had difficulties in preparing for the VT science class, such as the burden of making VT materials, the long preparation time, concerns over overlapping contents, consideration of learners' VT skills, and the themselves' drawing ability. Furthermore, they also had difficulties in proceeding for the class, like different preference among learners about Visualization and loss of objectives in science class using VT. Fifth, the participants needed support as follows: platform to share students' VT results; VT case books and teachers' guidebooks; physical environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.408-422
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• 2000

In this paper, we propose a generalized vector channel model for wireless communication systems using antenna arrays. The proposed channel model reflects path loss. spatial-temporal variation of shadowing, multipath fading , Doppler effect, spatial distribution of local scatterers and delay spread due to remote dominant scatterers. In addition, we use a discrete ray model in which respective ray signal experiences independent shadowing, fading and Doppler shift, and impinges on antenna arrays at a distinct angle. Based on the proposed mode. we derive the relations on the spatial and temporal correlations of the received signals and implement a spatial channel simulator. By comparing the theoretical values with the simulated ones, we verify the effectiveness of the implemented simulator. The simulator is then used to generate an arbitrary channel impulse response and to analyze the channel characteristics under various environments.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.40-46
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• 2013

In the chemical process industries, accidents have a high potential and large effects on catastrophic results. Therefore the safety management for accident prevention plays a crucial role to guarantee the process safety. For these reasons, many systematic methods for safety management system have been widely employed in the fields of chemical processes. PSM (Process safety management) is one of most representative methods. The audit system, which is one of PSM system components, evaluates the performance of PMS system. However, most existing safety audit systems are not systematic and these are performed based on knowledges and experiences of various specialist. Moreover, the safety audit is only performed based on each independent technical component. So, the results of safety audit are not a quantitative index but only a series of commentaries. Finally, it is very difficult to obtain the comparison with other plants or industries. In this study, the novel systematic method and index-based accident database of auditing safety management systems for quantitative assessment are proposed. First, the elements of safety audit replace technical methods to categories of accident database. The F-N curve of each category for accident database is employed to derive the index for quantitative assessment. The Accidental Factor Risk Index (AFRI) is suggested for evaluating the effect of each element in accident database and safety audit system. The safety audit can be modified according to the proposed index.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2298-2306
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• 2014

In this paper, we propose an open loop power control algorithm to control transmission power of the On-The-Move(OTM) Satcom terminal in GEO satellite communication environment. The proposed algorithm identifies the current channel state restricted by an obstacle or an antenna depointing loss based on the received beacon signal strength. On the basis of the determined signal attenuation causes, the OTM Satcom terminal turns off the RF output when an antenna tracking is failed. If the OTM Satcom terminal experiences a channel blockage by an obstacle, the terminal spreads the transmit data to increase data reception probability. To evaluate the performance of the proposed algorithm, we compare an adjacent satellite interference level and an outage probability. The results show the performance of the proposed algorithm is better than that of the conventional algorithm.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.199-208
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• 2009

Recently,IP-based broadcasting systems,such as Mobile-TV and IP-TV, have been widely deployed. These systems require a security system to allow only authorized subscribers access to broadcasting services. We analyzed the Conditional Access System, which is a security system used in the IP-based Pay-TV systems. A weakness of the system is that it does not scale well when the system experiences frequent membership changes. In this paper, we propose a group key distribution protocol which overcomes the scalability problem by reducing communication and computation overheads without loss of security strength. Our experimental results show that computation delay of the proposed protocol is smaller than one of the Conditional Access System. This is attributed to the fact that the proposed protocol replaces expensive encryption and decryption with relatively inexpensive arithmetic operations. In addition, the proposed protocol can help to set up a secure channel between a server and a client with the minimum additional overhead.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.275-280
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• 2007

A turbine stage consists of stators and rotors. The stator provides the required inlet flow conditions so that the rotor can produce the necessary power. Passing wakes generated from the trailing edge of the stator make an interaction with the rotor. In the present study, this flow mechanism is investigated using the numerical analysis. In case of a large gap distance between the stator and rotor, the flow can be solved independently. First, only the stator flow field is solved. Second, the rotor flow field is solved including the passing wake characteristics obtained from the stator analysis. The passing wake experiences the shearing as it approaches to the rotor blade leading edge. And it is chopped when it strikes the rotor blade. After that, the chopped wakes becomes the prolongation as it travels downstream. The flow according to the variation of the gap distance is also studied. Pressure jumps due to the passing wakes result in the pressure and lift loss and it gets stronger with the closer gap distance.

• Archives of Plastic Surgery
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• v.34 no.4
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• pp.485-489
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• 2007

Purpose: The basic vascular anatomy and versatility of the anterolateral thigh flap was reported firstly by Song in 1984 and then by Zhang who introduced the reverse flow pattern of this flap. In this case, the authors reviewed various articles and their experiences with the distally based anterolateral thigh flap and applied it for coverage of bone-exposed wound occurred at the distal of the disarticulated knee stump. We consequently reported the reliability and resourcefulness of this flap in the difficult and limited situation. Methods: A 67-year-old-man who had suffered from arteriosclerotic obliterans inevitably underwent the disarticulation at knee joint due to clinical deterioration. He presented to our clinic with soft tissue necrosis and bone exposure at the stump. We debrided the wound and conducted the distally based anterolateral thigh island flap by transecting proximal portion of descending branch of the lateral circumflex femoral artery and the $14{\times}10cm$ sized flap was transferred to cover the defect. The pedicle measured 14 cm in length with pivot point 7 cm above the patella. Results: The postoperative course was mainly uneventful except early venous congestion for 4 days and subsequent partial skin loss. The wound was healed by secondary intension and no other sequelae had been observed during follow-up period of 12 months. Conclusion: Despite the presence of various reconstructive choices, the distally based anterolateral thigh island flap can be designed to repair soft tissue defects around the knee region, providing its reliable blood supply and long pedicle length, especially in the challenging cases.