• Journal of Korean Society of Transportation
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• v.21 no.6
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• pp.57-65
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• 2003

Traffic congestion on the streets is the major concern of Metropolitan areas in Korea. Especially the signalized intersections are the main spots where traffic congestion is to be created. Currently the subway construction has been on the process in Taegu Metropolitan city. The subway stations are usually located at the intersections where a large number of vehicles and people are moving. During the constructional period, such an intersection creates profoundly a great deal of traffic congestion due to the open-cut constructional method. Under circumstance of the constructional method, the lane configurations should be changed frequently and the surface conditions make drivers uncomfortable. The propose of this study is to propose the improved method of traffic operation at the large circled intersection under the construction. The Signalized Modern Roundabout(SMR) is applied modifying from the modern roundabout. The geometric design and signal operation of SMR is developed in this study. To verify the operation of SMR the comparative study is conducted between the operation of the open-cut method and SMR method using the micro-simulation program, NETSIM. The result of simulation shows that the delay caused by the operation of SMR is not higher than that under the open-cut method. SMR makes also the constructional period shorten, makes the cost of construction lessened and makes drivers more comfortable as well than the method of open-cut. Therefore, the study concludes that the operation of SMR is more efficient, economic and safer method than that of open-cut method at the large circled intersection under construction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.637-652
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• 2012

The protector with the shape of '${\sqcap}$' in cross section can be set up in the tunnel, which can be constructed for enlargement of cross section, to keep traffic flow in the tunnel. It is impossible to install the rockbolt in the side wall of tunnel due to a limited space between the protector and cutting surface of side wall. The objective of this study is to suggest the optimum thickness of shotcrete lining without rockbolt on the side wall and to evaluate the stability of tunnel enlarged. Numerical analysis was performed to evaluate the displacement at the center of tunnel, the convergence of tunnel, and the stress in shotcrete lining in 4-lane NATM road tunnel enlarged from 3-lane NATM road tunnel. The vertical displacement at the center of tunnel and the convergence of crown in the tunnel with rockbolt in the side wall were almost similar to those in the tunnel without rockbolt in the side wall. The convergence of bench/invert and the stress in shotcrete lining without rockbolt on the side wall were greater maximum 0.57 mm and 1,300 kN/$m^2$ than those with rockbolt in the side wall. The increased convergence and the stress in shotcrete lining can be reduced in incerasing of thickness of shotcrete lining about 20% (5 cm) of standard thickness, 25 cm, of shotcrete lining.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.877-888
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• 2021

This study used three types of temporary shelters, tents, and prefabricated houses provided by the Chinese government for victims after the Wenchuan earthquake in 2008 as case study objects. Through literature review, 12 evaluation items were selected from the social, economic, and environmental elements of the sustainability of residential space design to analyze and evaluate three types of temporary shelters, and derive their respective characteristics and problems. The analysis results show that the temporary centralized settlements and tents had problems such as imperfect infrastructure, poor sanitation, narrow living space, no personal space, and inconvenience in life. Prefabricated houses had problems such as high construction costs, non-environmentally friendly building materials, occupation of arable land, low recycling rate of materials, and environmental pollution by waste. The common problem of the three types of shelters was that the government took the lead in the construction and distribution of shelters, and the disaster victims passively accept government support. Therefore, disaster victims were not actively involved in the construction and management of temporary communities. Secondly, the designs of all three types of temporary shelters did not fully consider the psychological needs of the victims, especially the need for safe and hygienic personal space. Finally, this research proposes improvement plans for the problems in the sustainable design of three temporary shelters and the construction and management of temporary communities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.479-493
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• 2023

The need for safety management has arisen due to the increasing number of years of operated underground structures, such as tunnels and utility tunnels, and accidents caused by those aging infrastructures. However, in the case of privately managed underground utility ducts, there is a lack of detailed guidelines for facility safety and maintenance, resulting in inadequate safety management. Furthermore, the absence of basic design information and the limited space for safety assessments make applying currently used non-destructive testing methods challenging. Therefore, this study suggests non-destructive inspection methods using ultrasonic and impact-echo techniques to assess the quality of underground structures. Thickness, presence of rebars, depth of rebars, and the presence and depth of internal defects are assessed to provide fundamental data for the safety assessment of box-type general underground structures. To validate the proposed methodology, different conditions of concrete specimens are designed and cured to simulate actual field conditions. Applying ultrasonic and impact signals and collecting data through multi-channel accelerometers determine the thickness of the simulated specimens, the depth of embedded rebar, and the extent of defects. The predicted results are well agreed upon compared with actual measurements. The proposed methodology is expected to contribute to developing safety diagnostic methods applicable to general underground structures in practical field conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.310-310
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• 2012

최근 전자산업의 발달에 따른 전자제품의 소형화 및 고기능화 요구에 대응하기 위하여 저항(resistor), 커패시터(capacitor), IC (integrated circuit) 등의 수동소자를 개별 칩(discrete chip) 형태로 형성하여 기판의 표면에 실장하는 기술이 일반화되고 있다. 그러나, 수동 소자의 내장 기술은 기판의 패턴 밀도의 급격한 향상과 더불어 수동소자의 내장 공간도 협소해지는 문제점이 있다. 상기의 문제점을 해결하기 위해 개별 칩 형태의 내장형 저항체를 박막 형태의 내장 저항체를 구현하는 기술의 개발이 최근 주목을 받고 있다. 박막 저항체는 기존의 권선저항 및 후막저항과 비교하여 정밀한 온도저항계수를 가지며 이동통신에 적용시 고주파 영역(GHz)에서의 안정성과 주파수 특성이 좋다는 장점들을 가지고 있다. 박막 저항 물질로는 높은 경도와 우수한 열적 안정성을 가지고 있는 TaN (tantalum nitride)이 주로 사용되고 있다. 일반적으로, TaN 박막은 스퍼터링을 사용하며 제조되며 TaN 박막의 성질은 탄탈륨과 질소의 화학정량비, 박막의 결함 정도, 또는 공정압력 및 증착 온도, 플라즈마 파워 등과 같은 공정조건 등의 변화에 민감하게 변화하므로, TaN 박막의 다양한 연구가 더 필요한 실정이다. 본 연구에서는 반응성 마크네트론 스퍼터링을 사용하여 TaN 박막을 Si 기판 위에 증착하였고 TaN 박막의 원하는 특성을 제어할 수 있도록 질소 분압과 total gas volume을 조절하여 공정을 최적화하는 연구를 진행하였다. 또한 tensile pull-off 방법을 이용하여 TaN 박막의 부착강도를 평가하였고, 온도 사이클 및 고온고습 환경에 노출된 TaN 박막들의 열화 특성들에 대하여 연구하였다.

• Fire Science and Engineering
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• v.33 no.6
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• pp.173-180
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• 2019

Oil tank fires need to be suppressed differently from other oil-related fires, due to the high-temperature flames and hot updraft above the tank, in the former case, that cause the destruction of large amounts of foam. We studied high-capacity foam discharge systems based on the standards of the American Petroleum Institute (API), National Fire Protection Association (NFPA), British Standard European Norm (BS EN), and the laws of Japan. The performance of a high-capacity foam discharge system was measured by conducting real fire experiments with model oil tanks. We concluded that lightweight and easily movable high-capacity foam discharge systems should be urgently introduced in domestic operations. Additionally, the obstacles faced by major tanks, such as long-distance installation of large-diameter fire hoses and narrowing of firefighting spaces, should be resolved depending on the conditions of the site.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.74-82
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• 2017

Localized corrosions damages in their structural sections can be occurred affected by installed environment conditions with high temperature as near the coastline and humidity or their poor maintenance situation. In bearing supports of steel bridges, especially, lower web and vertical stiffener in end girder support can be easily corroded because of relatively higher humidity due to the narrow space in the end of girder and the wetted accumulated sediments affected by rain water or antifreezing admixture leaked from expansion joint. It can be related to change in their structural performance. In this study, thus, bearing strength test specimens were fabricated considering corrosion damage in the web and vertical stiffeners and the change in their bearing strengths were experimentally evaluated. From the test results, localized corrosion damage of structural members in the end girder affected the bearing strength of end girder support, especially, localized corrosion damage of the vertical stiffener relatively highly affected their bearing strengths.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.3
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• pp.39-51
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• 2020

This study will examine the social issues and consumer awareness of sharing parking through the method text mining. In this experiment, the topic by keyword was extracted and analyzed using TFIDF (Term frequency inverse document frequency) and LDA (Latent dirichlet allocation) technique. As a result of categorization by topic, citizens' complaints such as local government agreements, parking space negotiations, parking culture improvement, citizen participation, etc., played an important role in implementing shared parking services. The contribution of this study highly differentiated from previous studies that conducted exploratory studies using corporate and regional cases, and can be said to have a high academic contribution. In addition, based on the results obtained by utilizing the LDA analysis in this study, there is a practical contribution that it can be applied or utilized in establishing a sharing economy policy for revitalizing the local economy.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.209-214
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• 2014

Current black boxes have a problem of storing unnecessary imagery data recordings without data classification. For this reason, users have to erase videos every time. This method is inadequate for black boxes with limited memory capacity. In this paper, we design and implement a system that recognizes traffic accident situations and saves these recordings by classifying them according to weighted values. The system was made to save video recorded at a 30-sec interval of every event to black box folders by changing names based on weighted value data under the external environment in a 1:10 scale model car. Based on this, when the tests were performed as a major car accident while driving, the videos were created in w2 folder, and when the tests were performed as a minor car accident while stopped, the videos were created in w1 folder.

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.16-25
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• 2009

In construction industry, the cost related to material is different from each other under the characteristic of projects. However, it has 40% of the whole cost in the composition of prime cost. Recently, While the construction work become bigger, specialized and complex, it is complex to carry in materials because of shortage of space. However, in many cases, material management has been underestimated as well as the material management is depending on experience of site managers so it has been studied about frequently. In this study, I suggest four classification methods of material characteristic ETO, ATO, MTO, MTS. I also analyze what the most efficient supply management of the site materials is through researching the characteristics of the material distribution. In conclusion, I would like to build the material management classification for the characteristics of materials.