• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.187-194
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• 2010

As the design of the pillar width (PW) of the parallel tunnels in downtown area, in which are located in plains zone with deep alluvium compared with mountain tunnels, is directly related with pre-compensation payment and costs of the underground area, it has to be planned as to keep minimum distance while securing the stability of the parallel tunnels. Although PW of downtown road tunnel in Korea is standardized as 1.5D(D: diameter of the tunnels), PW sometimes has to be reduced within 1.5D to adjust the tunnel lines to the city plan in the cases of the inlet and outlet of the tunnels. In this paper, the design and the analyses of optimum PW of the NATM type road tunnel in the downtown area are introduced. The relationship among the tunnel line planning and underground compensation fee, and ground characteristics are evaluated. In the determination of PW distance, the numerical analyses of underground road tunnels were performed, including the use of the strength decrease method and strength/stress ratio method. In the cases of inlet and outlet part of the tunnels where the stability of the pillars is poor due to contiguous construction of the parallel tunnels, the reinforcement methods are recommended for securing the stability. Numerical verification was performed for the reinforcement proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.372-381
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• 2019

In this study, the National Disaster Management System (NDMS) was analyzed to evaluate the disaster impact assessment standards for steep slopes. Problems in the assessment methods and systems were discovered, which could be reasons for poor reliability. The disaster-risk evaluation index needs improvement to evaluate various types of retaining walls, such as concrete/reinforced soil walls and reinforcing stone masonry. Additionally, using the same score for overturning, bulging, and efflorescence could be reasons for poor reliability, and different weighting factors are needed. Assessment methods are needed to subdivide the social influence evaluation index while considering environmental conditions of steep slopes, such as railroads and reservoirs. For the evaluation of steep slopes, standards for start and end points of steep slopes should be created for effective management, and disaster impact assessment needs to be performed after redevelopment from an advanced index for protection and reinforcement. These problems were derived from a current evaluation system, so a disaster impact assessment is necessary to supplement the results of this study.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.470-486
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• 2015

Two-arch tunnels require minimal spacing between the 2 tunnels and thus occupy small amount of land compared to parallel tunnels. But it is rather expensive. The parallel tunnel is not as expensive, but it requires more land than 2-arch tunnels. This may cause a problem when there is a land shortage. The new design is to connect these two types of tunnels by another pair of parallel tunnels where the separation distance is gradually increasing. The applicability of this new design to the cases where rock condition is not even fair has to be verified since the width of the pillar between the connecting tunnels can be quite narrow. Therefore both two and three dimensional numerical analyses were conducted and pillar stability was examined for rock classes IV and V in two different ways. Results showed that this new design is still effective for poor rock conditions if central pillar is properly reinforced by tension bolts as long as overburden is less than five times of the tunnel diameter.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.301-301
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• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.

• Journal of KIBIM
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• v.6 no.2
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• pp.29-38
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• 2016

Road bridges are deteriorating gradually, and it is forecasted that the number of road bridges aging over 30 years will increase by more than 3 times of the current number. To maintain road bridges in a safe condition, current safety conditions of the bridges must be estimated for repair or reinforcement. However, budget and professional manpower required to perform in-depth inspections of road bridges are limited. This study proposes an estimation model for safety rating of road bridges by analyzing the data from Facility Management System (FMS) and Yearbook of Road Bridges and Tunnel. These data include basic specifications, year of completion, traffic, safety rating, and others. The distribution of safety rating was imbalanced, indicating 91% of road bridges have safety ratings of A or B. To improve classification performance, five safety ratings were integrated into two classes of G (good, A and B) and P (poor ratings under C). This rearrangement was set because facilities with ratings under C are required to be repaired or reinforced to recover their original functionality. 70% of the original data were used as training data, while the other 30% were used for validation. Data of class P in the training data were oversampled by 3 times, and Repeated Incremental Pruning to Produce Error Reduction (RIPPER) algorithm was used to develop the estimation model. The results of estimation model showed overall accuracy of 84.8%, true positive rate of 67.3%, and 29 classification rule. Year of completion was identified as the most critical factor on affecting lower safety ratings of bridges.

• Journal of Engineering Education Research
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• v.21 no.1
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• pp.27-36
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• 2018

This study aims to deduce operational implication of R-WeSET program through women students in science & engineering and companies's perception and assessment on the basis of NCS key competency. The significant results are as follows. Firstly, companies and women students in science & engineering share a similar perception on importance of NCS key competencies. The programs should be reviewed and improved for women students who are truly aware of companies' needs. Secondly, the main areas of NCS key competency that are poor in companies' perception are 'positive thinking & drive', 'creativity & challenge spirit', 'communication skills' and 'problem-solving skills'. To enhance these weak skills, activating the actual programs such as "Convergence Design Camp", "Field Adaptability Improvement" and developing the new communication program are required. Lastly, most of women students have attained the satisfying result from "Field Competency Reinforcement Program". Especially, "Industry Field Training" shared the great progresses on all skills of key competency, hence why the progressive model should be developed in the future. This study figures out who's the right person for the 4th Industrial Revolution era, producing a meaningful result in order to change in the higher education system of women students and to grow human resources who will contribute to the community and company.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.9-17
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• 2012

In 1960's, Korea had concentrated on economic development, in the meantime the existing problem which is an avoiding rural settlement phenomenon such as a farming population decrease, an unstabel income, poor surroundings, etc. could intensify. And because of an exodus from agricultural area caused by industrialization and a fall of agricultural farm price as a result of domestic agricultural market opening in accordance with FTA, in 2004 Korean government excuted the integrated rural-village development plan as a measure to provide more support for agricultural villages. The integrated rural-village development plan means that inter-connected with villages which have potnetial and developed it as a unit of small-zone, also we can assume it a Down-up development type because residents participate and lead this plan directly. But, this plan made progress rapidly as a countmeasure of government so, it needs to evaluate for completed project area and make an improvement for a sustainable undertaking. Therefore, this study categorized project contents systematically into two parts of Hardware and Software, after that composed of 4 large-parts, 13 mid-parts and 43 small-parts from Inje-Yongdai zone which was designated for an integrated rural-village development plan in 2004. And a result of analysis for project contents priorities by hierarchy analysis method showed the Regional capability reinforcement is selected for the most important project content by 3 stakeholders who are specialists (514pts.), Korea Rural Community Corporation staffs (694pts.), local government officers (688pts.)

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.9-17
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• 2011

It is possible to set up the Roadside Barrier which is suitable for Performance Evaluation Criteria by domestic standard. But a number of section of expressway roadside have old guardrail that was installed before reform the guideline. These poor performance guardrails threaten driver's life. There is lots of difficult problem to change old guardrails that are installed 2,777km in expressway of whole road side at the same time. Especially budget problem. The purpose of study is to develop performance improvement guardrails by the minimum reinforcement. In this study, guardrail improvement method(SB1, 3, 5 grade) is developed through crash simulation using LS-DYNA 3D and vehicle crash test. And it's expected not only to decrease of collision accident but to increase safe level. Of course one thing that can't be missing is to reduce a lot of budget of guardrail change.

• Information and Communications Magazine
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• v.24 no.4
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• pp.27-35
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• 2007

음성 통신을 할 때 배경 잡음이 존재하게 되면 일반적으로 음질이 저하된다. 이것은 잡음 자체가 듣기 싫다거나 음성을 더 작게 들리게 만들기 때문이기도 하고 음성 코덱이 잡음이 섞이지 않은 깨끗한 음성에 최적화되어 있어서 잡음이 섞인 음성에 대한 코딩 효율이 떨어지기 때문이기도 하다. 이 논문에서는 잡음에 의한 음성 통신의 품질 저하를 막기 위한 방법으로서 음성 향상(speech enhancement) 기술과 음성 강화(speech reinforcement) 기술에 대해 소개한다. 음성 향상 기술이란 전송부의 마이크에서 녹음된 잡음과 음성이 섞인 입력 음성으로부터 깨끗한 음성을 추정하는 기술을 말한다. 음성 향상 기술은 상당히 오랜 기간 동안 연구되어 온 기술이며, 최근에는 각 파라미터의 분포에 의존하는 방법보다 확률 모델에 기반한 방법이 각광을 받고 있으며 인간의 청각 특성을 고려한 음성 향상 방법도 제안되고 있다. 음성 강화 기술이란 수신단에서 주변 잡음에 따라 전송되어 온 음성을 주파수별로 증폭하여 더 잘 들리도록 만드는 기술이다. 음성 향상이 내 주위의 잡음이 상대방에게 들리는 음성에 미치는 영향 혹은 상대방 주변의 잡음이 나에게 들리는 소리에 미치는 영향을 줄여주는 기술이라면 음성 강화는 내 주위의 잡음이 나에게 들리는 음성에 미치는 영향을 상쇄해 주는 기술이다. 이 경우 주변 잡음은 어떤 전자 시스템도 거치지 않고 귀로 직접 들어오기 때문에 잡음 자체를 줄여 주는 것은 힘들고 전송되어 온 음성을 적절히 증폭 혹은 변형함으로써 귀에 들리는 음질 또는 명료성을 개선하게 된다. 이 논문에서는 통계 모델을 기반으로 한 음성 향상 기법과 인간의 청각 특성을 고려한 음성 향상 기법, 그리고 음성 강화 기법에 대해 설명한다.을 시도한 결과 안정적이고 반복 가능한 급성 심부전 모델을 얻을 수 있었다. bench scale실험결과와 같이 AOC는 배수관망에서의 박테리아 증식과 크게 상관관계를 갖고 있는 것으로 밝혀졌다.)', 'have a headache (2.10±0.79)', 'poor memory (2.09±0.83)', 'no appetite (1.99±0.85)', As for the correlation between iron parameter and clinical symptoms related to anemia, the hematocrit rate was negatively correlated with 'get a cold easily', 'pale face', 'feeling blue', 'difficult digestion' (p<0.05). The level of iron was negatively correlated with 'tired out easily', 'get a cold easily' (p<0.05) and TS (%) were negatively correlated with 'tired out easily (p<0.05)', 'get a cold easily (p<0.01). Our study resulted that the prevalence of a iron deficiency of a middle school girl is very high, therefore the guidelines for iron supplementation and nutritional education to improve their iron status should be provided.한 질소제거를 N-balance로부터

• Smart Structures and Systems
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• v.9 no.5
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• pp.393-410
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• 2012

Conventional geotechnical instrumentation techniques available for monitoring of slopes, especially soil-nailed slopes have limitations such as electromagnetic interference, low accuracy, poor longterm reliability and difficulty in mounting a series of strain sensors on a soil nail bar with a small-diameter. This paper presents a slope monitoring system based on fibre Bragg grating (FBG) sensing technology. This monitoring system is designed to perform long-term monitoring of slope movements, strains along soil nails, and other slope reinforcement elements. All these FBG sensors are fabricated and calibrated in laboratory and a trial of this monitoring system has been successfully conducted on a roadside slope in Hong Kong. As part of the slope stability improvement works, soil nails and a toe support soldier-pile wall were constructed. During the slope works, more than 100 FBG sensors were installed on a soil nail, a soldier pile, and an in- place inclinometer. The paper presents the layout and arrangement of the instruments as well as the installation procedures adopted. Monitoring data have been collected since March 2008. This trial has demonstrated the great potential of the optical fibre monitoring system for long-term monitoring of slope performance. The advantages of the slope monitoring system and experience gained in the field implementation are also discussed in the paper.