• International Journal of Highway Engineering
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• v.6 no.1 s.19
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• pp.25-36
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• 2004

The total length of paved roads in Korea is 67,265 Km, and among these roads, about 40% of the national highways and 98% of local roads are paved with asphalt concrete. The major distress to asphalt pavement is rutting and fatigue crack. The permanent deformation including rutting accounts for about 75% of this distress. UTW(Ultra-Thin Whitetopping), which is known for its high-quality performance in asphalt pavement with rutting and cracking, seems to reduce maintenance costs significantly if it is used as the maintenance/repair method for domestic asphalt pavement. In the research, static load test was conducted to establish a behavior of Whitetopping under traffic and environmental condition. It showed that the effect of the thickness of the concrete layer and the temperature change was significant. In addition, the tensile strain as the wheel load position was close to interior and edge of concrete slab were increased up to 75% of maximum tensile strain. It showed that joint spacing must be considered in UTW design procedure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.119-127
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• 2013

In cases of wooden structure and wooden house installed on the outside, metal goods used for basic connection are usually screw bolts, strainless nails and general iron nails. As metal connections on wood are directly exposed to exterior environment, friction resistibility of nails on metal connections declines and continual defects on this are generated and maintenance for it is required. However, experiments and analyses for preparing basic data for improvement of the problems have been not conducted so far and wooden structures with defects are abandoned. Accordingly, by analyzing friction resistibility of connections by each kind of woods and metal goods, the study aims to suggest to use metal goods appropriately by kinds of woods and manufacture conditions with analysis on characteristics of resistibility of extracting nails for solving such problems and to secure basic data for establishing maintenance, repair and reinforcement plans.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.382-382
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• 2022

우즈베키스탄은 수자원의 의존도가 매우 큰 국가이다. 과거로부터 농업이 발달하였으며 하천에서 용수를 취수하여 농업용수로 이용하지만 연간 강수량이 적어 수자원의 대부분은 중앙아시아 공유 하천인 Amudarya강과 Syrdarya강에서 취수하여 사용한다. 이들 하천의 수자원은 하천의 상류에 위치한 키르기스탄과 타지기스탄에서 주로 기원하고 있어 우즈베키스탄은 물안보에 매우 취약한 실정이다. 우즈베키스탄은 물사용량 중 약 90%가 농업용수로 이용되고 있으나 수자원의 양이 부족하고 관개시설의 노후화 및 비효율적인 용수공급으로 농업생산성이 낮다. 우즈베키스탄은 수자원의 관리를 위하여 주요 하천 및 수로지점에 유량관측소를 설치하여 운영하고 있지만 시설의 노후화로 인하여 관측자료의 정확도가 낮으며 수기로 일단위로 측정하여 보고하는 방식으로 인하여 적기에 합리적인 용수배분 의사결정이 어려운 실정이다. 이러한 문제를 해결하기 위한 하나의 방법으로 우즈베키스탄 수자원부는 우즈베키스탄에 수자원 관리 정보화사업을 소개하고 적용하는 것이 필요하다고 판단하였으며, 수자원정보화사업을 우즈베키스탄에 적용하기 위하여 수자원정보화에 있어서 선진국이라 할 수 있는 한국의 기술을 우즈베키스탄에 활용하도록 요청하였다. 이에 따라 2016년부터 "우즈베키스탄 ICT기반의 물관리 마스터 플랜 수립 및 시설기반강화 시범사업"을 수행되게 되었다. 본 사업의 목적은 "수자원정보시스템의 개발 및 역량강화로 수자원정보화 기반을 구축"하는 것으로 우즈베키스탄 전국에 ICT 기반의 수문계측 및 수자원관리 시스템 구축 등 선진화된 수자원 정보 시스템을 개발하고, 향후 지속가능한 유지·보수·관리를 위한 현지 전문가 대상의 역량 강화 사업(수문계측기기, 시스템운영 및 유지보수 등)을 통해 본 사업의 현지정착을 도모하고자 하는 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.637-647
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• 2014

In pressurized water reactors, the upper head of the reactor pressure vessel (RPV) contains numerous control rod drive mechanism (CRDM) nozzles. These nozzles are fabricated by welding after being inserted into the RPV head with a room temperature shrink fit. The tensile residual stresses caused by this welding are a major factor in primary water stress corrosion cracking (PWSCC). Over the last 15 years, the incidences of cracking in alloy 600 CRDM nozzles have increased significantly. These cracks are caused by PWSCC and have been shown to be driven by the welding residual stresses and operational stresses in the weld region. Various measures are being sought to overcome these problems. The defects resulting from the welding process are often the cause of PWSCC acceleration. Therefore, any weld defects found in the RPV manufacturing process are immediately repaired by repair welding. Detailed finite-element simulations for the Korea Nuclear Reactor Pressure Vessel were conducted in order to predict the magnitudes of the repair weld residual stresses in the tube materials.

• Korean Journal of Construction Engineering and Management
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• v.23 no.5
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• pp.23-33
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• 2022

Cracks, which account for the largest proportion of defect lawsuits in apartment buildings, are not clear on the criteria for defect determination, so judgments about defects are mixed. Interlayer cracks, which account for most of the crack defect judgment amount, tend to be judged as defects regardless of the crack width or condition, and repair methods are mostly set uniformly. This starts from the problem that the standards of the Ministry of Land, Infrastructure and Transport and the Construction Appraisal Practice, which the courts use as standards, do not match. It is necessary to establish a defect determination standard that can be applied to all stakeholders through the amendment of laws and the revision of the Court Appraisal Practice. In addition, it is necessary to apply the crack repair method according to the width and condition of the interlayer crack. If the defect determination and the application of the repair method for cracks are rationalized, it could serve as an opportunity to change the current trend of defect disputes that rely only on litigation.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.229-239
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• 2008

This paper compares the load transfer efficiency between precast concrete pavement specimen and typical concrete pavement specimen by means of laboratory and field tests. An experimental method was developed to evaluate the load transfer efficiency of the dowel bars buried in the concrete pocket and grouted with cement mortar. The test results showed that the load transfer efficiency of the specimen for the dowel bars repaired with grout was equivalent to that of the control specimen. In addition, a series of FWD field tests were conducted on the precast pavement to evaluate the joint stiffness. The field test results revealed that the central deflection of the precast slab slightly increased but the load transfer efficiencies at the joints were almost the same as those in the typical concrete pavement slab.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4171-4176
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• 2012

The conventional block systems for railway signaling currently in operation in Korea have not been electrified or integrated and therefore there have been difficulties in terms of construction and maintenance. Two independent systems have been installed for ABS and LEU of ATP system (for speeded-up lines), although they deal with the same signaling information at the same location in order to control the trains. In these conventional ABS and LEU, a number of duplicate modules are installed in each device including lamp detection units and power supply units and it results increased manufacturing costs and maintenance efforts. This paper deals with the prototype development of integrated electronic block system with CPU-based digital control methods in order to overcome the limitations of the conventional ABS. The suggested system is the integration of the conventional ABS with LEU of ATP and it is also applicable for the non-ATP sections as well.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.9-12
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• 2016

본 논문에서는 지진 및 재난상황을 신속하게 대중에게 전파하기 위해 상황실에서의 통제에 따라 정해진 경보방송을 수행하고, 대용량 스피커를 통해 출력할 수 있는 장치를 소개한다. 통신망은 VHF와 위성을 이용하는 이중화로 구성하여 재난발생 시 통신장애에 대한 서비스를 안정화하고, 통신부/제어부/입출력부/앰프부/전원부 등을 유니트로 설계하여 유지보수를 수월하게 할 수 있도록 구성하였다. 야외 환경에서 동작되는 장비는 먼지로부터 보호하고 방수기능이 포함되어 있으므로 밀폐형 함체 내부에 장착된다. 혹한 및 혹서의 날씨에도 장비 운영에 문제가 없도록 장비 내부에 히팅을 하고, 팬을 이용하여 공기 배출을 통해 온도 조절 기능을 수행한다. 배터리를 내장하여 불안정한 상용 전원 공급 조건에서도 안정적으로 운영될 수 있도록 설계하였다.

• Magazine of the Korea Concrete Institute
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• v.10 no.2
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• pp.109-117
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• 1998

중트럭통행으로 인한 철근콘크리트 교량바닥판의 열화는 교량구조물을 유지보수하는데 있어서 심각한 문제중 하나이며, 프리캐스트 바닥판을 이용한 교량바닥판의 시공 및 교체 방법이 실용적이며, 효과적인 방법으로 인식되고 있다. 본 연구에서는 프리캐스트 바닥판 사이 연결부에 대한 정적실험을 수행하여 실험부재의 탄성영역 및 극한 상태하에서 프리캐스트 바닥판 사이 교축직각 방향 연결부의 강성 및 강도를 평가하였다. 정적실험결과, 무수측 모르나트를 채움재로 사용한 프리캐스트 바닥판 사이 교축방향 연결부는 교축방향으로 적정량의 프리스트레스를 도입함으로서 일반 현장타설 철근콘크리트 바닥판에 비해서 균열에 대한 사용성이 향상되는 것으로 나타났다.