• 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 the Korean Institute of Gas
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• v.21 no.6
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• pp.15-22
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• 2017

The pressure safety valve is very important device for securing the safety in the facilities which is operated by high pressure gases. The performance test should be periodically inspected by relate law because the failure of pressure safety valves might be main causes of serious accidents in the industrial fields. Shop test is mainly use for inspecting the performance test of pressure safety valves but the test method is not to be a solution for securing the safety. So, the development of alternative method is required. In this paper, there is a limit to securing the safety if the performance test is with just shop test. The limitation is checked from analysis result based on performance test results of pressure safety valves. The necessity for introducing the in-service test is reviewed to surmount the limitation. As a result, in-service test method should be developed and introduced to improve the inspection efficiency and economical loss. Also, it can be reduce the risk level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2508-2519
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• 1994

In this thesis, two possible schemes for power feeding are considered. The first one is the network power feeding, and the other is the power feeding from the rechargeable battery. Though each scheme has its merits and demerits, the domestic network operator has proposed the latter due to the large deviation of line resistance, high power loss, and safety. This scheme, however, has several problems. The usage is limited by the life of battery leading to the failure of minimal voice service for many hours. The space occupation of that battery is another serious problem. Moreover, the network opeator should have overhead of maintenance and repair. In order to alleviate such the difficulties, the sealing current is introduced through the subscriber loop. Flowing the current into the loop prevents from rusting. This thesis designs a power controller using PEB2025 to control various amount, duration, and period of this sealing current, to achieve the optimum current supply for sealing.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.216-222
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• 2014

Chloride attack to reinforced concrete structures located in seaside can cause a serious problem of durability and maintenance during the service life. Corrosion of reinforced steel bars in concrete decreases the bond strength and finally causes the detachment of concrete cover. Polymer cement mortar is usually adopted to repair the deteriorated RC structures because of its strong bonding property. The recovered load-carrying capacity after the repair was simulated by non-linear FEM analysis. The properties of concrete, repairing materials, bonding materials and reinforced bar were used as input data. Four types of redispersible polymer powders were used as components of polymer cement mortar. Pull-off tests were carried out to examine the bond properties such as rigidity and strength. Effects of a corrosion inhibitor and the loss of reinforced bars due to the corrosion were also considered in this study. FEM modeling and analysis were conducted to propose the universal model. Physical bonding in the relationship between repair materials and steel reinforced bar is more dominant than chemical bonding.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.6
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• pp.535-544
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• 2005

The management of mandibular condyle fractures continues to be a subject of much debate. It is suggested that, if not properly managed, these fractures may give rise to serious problems, such as malocclusion, mouth opening limitation, temporomandibular joint disorders. Treatment planing of mandibular condyle fractures is very important. The aim of this present study was to evaluate the long-term results according to treatment methods in condylar fractures. Also, it was to evaluate results of treatment according to condylar fracture level. We conducted a retrospective analysis of 43 mandibular condyle fractures. 43 patients followed for average period of 9.00 years(mini. 7yr, max. 12yr). All patients underwent a clinical and radiologic evaluation focusing on mouth opening, mandibular movements, TMJ function, change of ramal height, condylar remodelling. If the level of fracture was positioned in high, especially in level II, mandibular movement disability and ramus length loss was more prominent. This results were similar to the cases of treatment of fragment removal. In high level fracture and fragment removal cases, It is thought that more intensive and long term management are needed than other treatment cases using different operation methods. Also, direct fixation by each approach showed good results in mandibular movement, ramal height change and condylar shape. Through this results, accurate reduction of the mandibular condyle fractures was a very important factor in postoperative prognosis.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.58-66
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• 2009

Due to a shortage of professional labor and the stagnant construction industry in recent days, there has been an increasing demand for securing profitability through cost reduction. Though its importance in the cost and its great influence on the safety and durability of structures, the labor intensiveness of rebar work has caused a serious problem of rising cost accompanied by the loss of rebar materials. In the plant manufacturing process, rebar is cut and bent at the automated facilities and conveyed to the construction site, which makes it possible to manufacture higher-quality bars and to reduce the losses from rebar materials. Different from the expectation, however, this type of plant manufacturing still has not been active since its first introduction in 1990s. In this study, a research on the actual condition of rebar manufacturing plant has been implemented and a standardized rebar manufacturing has been provided as a way to activate rebar manufacturing.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.364-374
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• 2016

With vast amounts of spectrum available in the millimeter wave (mmWave) band, small cells at mmWave frequencies densely deployed underlying the conventional homogeneous macrocell network have gained considerable interest from academia, industry, and standards bodies. Due to high propagation loss at higher frequencies, mmWave communications are inherently directional, and concurrent transmissions (spatial reuse) under low inter-link interference can be enabled to significantly improve network capacity. On the other hand, mmWave links are easily blocked by obstacles such as human body and furniture. In this paper, we develop a multi-hop relaying transmission (MHRT) scheme to steer blocked flows around obstacles by establishing multi-hop relay paths. In MHRT, a relay path selection algorithm is proposed to establish relay paths for blocked flows for better use of concurrent transmissions. After relay path selection, we use a multi-hop transmission scheduling algorithm to compute near-optimal schedules by fully exploiting the spatial reuse. Through extensive simulations under various traffic patterns and channel conditions, we demonstrate MHRT achieves superior performance in terms of network throughput and connection robustness compared with other existing protocols, especially under serious blockage conditions. The performance ofMHRT with different hop limitations is also simulated and analyzed for a better choice of the maximum hop number in practice.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.142-152
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• 2013

The network mobility basic support (NEMO BS) protocol has been investigated to provide Internet connectivity for a group of nodes, which is suitable for intelligent transportation systems (ITS) applications. NEMO BS often increases the traffic load and handover latency because it is designed on the basis of mobile Internet protocol version 6 (MIPv6). Therefore, schemes combining proxy MIPv6 with NEMO (P-NEMO) have emerged to solve these problems. However, these schemes still suffer from packet loss and long handover latency during handover. Fast P-NEMO (FP-NEMO) has emerged to prevent these problems. Although the FP-NEMO accelerates handover, it can cause a serious tunneling burden between the mobile access gateways (MAGs) during handover. This problem becomes more critical as the traffic between the MAGs increases. Therefore, we propose a scheme for designing an improved FP-NEMO (IFP-NEMO) to eliminate the tunneling burden by registering a new address in advance. When the registration is completed before the layer 2 handover, the packets are forwarded to the new MAG directly and thereby the IFP-NEMO avoids the use of the tunnel between the MAGs during handover. For the evaluation of the performance of the IFP-NEMO compared with the FP-NEMO, we develop an analytical framework for fast handovers on the basis of P-NEMO. Finally, we demonstrate that the IFP-NEMO outperforms the FP-NEMO through numerical results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11C
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• pp.1498-1509
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• 2004

In this paper, we evaluate the performance of a noncoherent OOK (On-Off Keying) UWB (Ultra Wide Band) system based on power detection with noise power calibration and noise power windowing for ubiquitous sensor network applications in typical indoor wireless channels. Utilizing noise power calibration and noise power windowing, the current noise information can be initially or adaptively provided to determine suitable detection threshold value for signal demodulation. Simulation results show that the noncoherent OOK UWB system using noise power calibration achieves good BER (Bit Error Rate) performance which is favorably comparable to that of the system using the ideal adaptive threshold, while maintaining simple receiver structure. However, despite the serious loss of the data transmission rate, the performance improvement by noise power windowing is not so remarkable. furthermore, these performance results are similarly maintained in BEE 802.15 Task Group 3a UWB indoor channel model, and it is also revealed that the BER performance can be significantly improved by increasing the pulse repetition rate.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.123-135
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• 2014

Earthquakes can cause serious loss of life and significant property damage. Thus, the study of active faults is important in evaluating future fault activity and hazards caused by future earthquake events. Structural mapping and the tracing of active faults are the primary steps in studies of active faults. Until now, active faults in South Korea have been mapped using aerial photography, satellite images, and low-quality DEMs. Lineament analysis as a means of identifying active faults is relatively difficult in Korea due to geological characteristics (weak tectonic activity) and dense vegetation cover. In this paper, we introduce the basic concept of the LiDAR technique (a new prospective remote sensing method) and a data analysis method that can overcome these problems. This paper will contribute to a better understanding of the airborne LiDAR technique and its application to South Korea. Some preliminary results from Korean and USA LiDAR data show the usefulness of this technique for tracing lineaments, active faults, and terraces in South Korea.