• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.201-220
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• 2023

Power cable tunnels is one of the underground structures meant for electricity transmission and are constructed using shield TBM method when transitting across urban and subsea regions. With the increasing shaft depth for tunnels excavation when the shield TBM excavated the rock mass, the review of selecting closed-type shield TBM in rocks becomes necessary. A simplified shield TBM design method is also necessary based on conventional geotechnical survey results. In this respect, design method and related design program are developed based on combined results of full-scale tests, considerable amount of accumulated TBM data, and numerical simulation results. In order to validate the program results, excavation data of a completed power cable tunnel project are utilized. Thrust force, torque, and power of shield TBM specification are validated using Kernel density concept which estimates the population data. The robustness of design expertise is established through this research which will help in stable provision of electricity supply.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.507-515
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• 2008

In this study, a method predicting the displacement response of structures from the measured dynamic strain signal is proposed by using mode decomposition technique. Evaluation of bridge stability is normally focused on the bridge completed. However, dynamic loadings including wind and seismic loadings could be exerted to the bridge under construction. In order to examine the bridge stability against these dynamic loadings, the prediction of displacement response is very important to evaluate bridge stability. Because it may be not easy for the displacement response to be acquired directly on site, an indirect method to predict the displacement response is needed. Thus, as an alternative for predicting the displacement response indirectly, the conversion of the measured strain signal into the displacement response is suggested, while the measured strain signal can be obtained using fiber optic Bragg-grating (FBG) sensors. As previous studies on the prediction of displacement response by using the FBG sensors, the static displacement has been mainly predicted. For predicting the dynamic displacement, it has been known that the measured strain signal includes higher modes and then the predicted dynamic displacement can be inherently contaminated by broad-band noises. To overcome such problem, a mode decomposition technique was used. Mode decomposition technique estimates the displacement response of each mode with mode shape estimated to use POD from strain signal and with the measured strain signal decomposed into mode by EMD. This is a method estimating the total displacement response combined with the each displacement response about the major mode of the structure. In order to examine the mode decomposition technique suggested in this study model experiment was performed.

• Journal of the Korea Institute of Building Construction
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• v.9 no.5
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• pp.79-86
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• 2009

In a steel structure, spray-applied fire resistive materials are crucial in preventing structural strength from being weakened in the event of a fire. The quality control of such materials, however, is difficult for manual workers, who can frequently be in short supply. These skilled workers are also very likely to be exposed to environmental hazards. Problems with construction work such as this, which are specifically the difficulty of achieving quality control and the dangerous nature of the work itself, can be solved to some degree by the introduction of automated equipment. It is, however, very difficult to automate the work process, from operation to the selection of a location for the equipment, as the environment of a construction site has not yet been structured to accommodate automation. This is a fundamental study on the possibility of the automation of spray-applied fire resistive coating work. In this study, the linkability of the cutting-edge RTLS to an automation system is reviewed, and a scenario for the automation of spray-applied fire resistive coating work and system composition is presented. The system suggested in this study is still in a conceptual stage, and as such, there are many restrictions still to be resolved. Despite this fact, automation is expected to have good effectiveness in terms of preventing fire from spreading by maintaining a certain level of strength at a high temperature when a fire occurs, as it maintains the thickness of the fire-resistive coating at a specified level, and secures the integrity of the coating with the steel structure, thereby enhancing the fire-resistive performance. It also expected that if future research is conducted in this area in relation to a cutting-edge monitoring TRS, such as the ubiquitous sensor network (USN) and/or building information model (BIM), it will contribute to raising the level of construction automation in Korea, reducing costs through the systematic and efficient management of construction resources, shortening construction periods, and implementing more precise construction

• Korean Journal of Heritage: History & Science
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• v.42 no.2
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• pp.86-109
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• 2009

Mireuksa Temple was founded during the reign of King Mu of Baekje(AD 600-641). The circumstance of the construction of this temple is documented in "Memorabilia of the Three Kingdoms (Samgukyusa)". The pagoda named stone pagoda at Mireuksaji temple stands outside the main sanctuary of the western area. The south and west sides of the stone pagoda have completely collapsed, leaving only the eastern facade of six of its levels intact. Through the recent discovery of sarira reliquary we can see that the erection of this pagoda was in 639. So owing to accumulation of excavation results about Baekje temple site and vigorous academic exchange, it is possible that architecture of western pagoda at Mireuksaji temple can be understood in connection with the architectural development of wooden pagoda from 6th to early 7th century in East Asia. So this study is on the consideration of building of this pagoda putting first structure of upper part and cross-shaped space in 1st floor. It was considered that the material characteristics as stone could be applied to the temple pagoda architecture of large scale. The results are as follows. First, it had been built in recognition that the outer and inner part of pagoda should be separated. As it is the expression of structural system in temple pagoda architecture of large scale at that time. In pagoda there was a self-erected structure and the members of outer part of it were constructed additionally. Second, in Mireuksaji stone pagoda there is central column with stones. With inner part of pagoda it can be regarded as mixed structural system that constitutes central contral column and inner structural part. And it could be a kind of middle step to more developed structure of whole as wooden pagodas in Japan. Third, as the sarira reliquary was in central column on the first floor, the cross-shaped space could be made. The formation of this space was so on the natural meaning of sarira that the concept as memorial service of graves could be apllied to the pagoda. The style of tomb in Baekje was expressed to the space of 1st floor in pagoda where Sarira had been mstalled. That was not only effective presentation of symbolic space but also easier method in the use of same material.

• 주택과사람들
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• no.54 s.71
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• pp.185-206
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• 1996

1.건설제도의 국제화와 경쟁기반 구축 $\bullet$건설산업을 기획$\cdot$설계$\cdot$시공$\cdot$감리$\cdot$사후관리 등 전 분야에 걸쳐 경쟁력 있는 산업으로 육성-기획$\cdot$설계$\cdot$시공$\cdot$감리$\cdot$유지관리 등 건설산업 전반에 관한 기본사항을 법제화-대규모 공사의 경우 발주자를 대신하여 건설공사의 기획$\cdot$설계$\cdot$발주$\cdot$감리$\cdot$시공관리 등 업무의 전부 또는 일부를 종합적으로 조정$\cdot$관리하는 $\lceil$건설사업관리$\rfloor$제도를 도입 $bullet$건설공사 $\lceil$현장실명제$\rfloor$도입을 통한 하도급제도의 정비-전문건설업자로부터 하도급, 위탁, 고용 등의 형태로 공사에 참여하는 현장근로자를 신고 받아 권익을 보호하고 시공책임도 부과하는 $\lceil$현장실명제$\rfloor$도입 $\bullet$공사완성보증제, 손해배상보증제도를 도입하고, 신용상태 $\cdot$시공능력에 따라 보증 요율 등을 차등화 하여 부실업체를 배제 $\bullet$건설공사관련 각종 계약서와 시방서 등 제기준을 정비하여 발주자$\cdot$시공자 등 건설주체간의 역할과 책임을 명확화$\bullet$건설분쟁을 신속하고 객관적으로 조정$\cdot$중재하기 위하여 $\lceil$건설분쟁중재원$\rfloor$으로 확대 개편 2. 건설인력의 육성과 고용안정$\bullet$경쟁력 제고의 관건인 우수인력 확보를 위하여 대학교육 제도의 개선을 포함한 건설 인력 수급대책을 추진 - 대학의 건설관련 학과 정원을 2000년까지 매년 일정규모로 증원하여 고급기술 인력을 배출 현재 50$\%$에 불과한 건설관련 국가기술자격자를 2000년에 70$\%$까지 제고 - 감리 등 전문인력을 양성하고, 선진외국 감리 회사를 활용하여 국내 업계와의 경쟁을 유도 $\bullet$건설현장의 최일선에서 품질을 담당하고 있는 건설기능공의 고용안정과 복지향상을 위한 획기적인 대책을 마련 - 건설기능공의 자긍심과 사회적 책임의식을 고취하기 위해 기능공이 여러 현장을 전전하여 근무하더라도 경력관리, 공제금 등의 합산 관리가 가능하도록 $\lceil$건설 근로자 복지카드$\rfloor$제도를 도입 *$\lceil$건실시연구단$\rfloor$을 구성$\cdot$구체적인 운영방안을 수립 - 건설 업체 실정에 맞는 현장위주의 기능검정제도 도입 $\cdot$자격증이 현장에서 요구되는 기능수준과 숙련도를 제대로 반영할 수 있도록 검정방법을 현장 실기위주로 개선하고 자격검정업무도 건설협회 등의 자격 검정능력을 향상시켜 위탁$\cdot$시행하는 방안을 검토 3. 공사시행기관의 전문성과 책임성 제고 $\bullet$시장이 개방되어 건설공사가 국제적인 관행에 따라 이루어질 것에 대비하여 시행기관에 계약$\cdot$공사관리 등 전문직공무원을 집중 교육하여 양성 $\bullet$ 조달청이 대행하여 공사계약을 하는 경우라도 설계변경은 발주기관이 자체적으로 할 수 있도록 허용 $\bullet$ 기술직 공무원의 기술향상을 위하여 관련 공무원의 확충, 해외연수, 현장교육 강화 등을 지속적으로 추진 $\bullet$ 충분한 사전조사를 거쳐 사업계획을 수립하도록 $\lceil$건설공사 시행절차$\rfloor$를 규정 $\bullet$ 공사기간 3년 이상의 공사에 대하여는 최대한 계속비사업으로 편성토록 계속비제도의 운영을 활성화 4. 건설현장의 품질관리체제 구축 $\bullet$ 현장배쳐플랜트 설치를 확대하여 레미콘의 품질관리를 일원화하고 현장에서 레이콘을 배합하는 건식공법을 채택 - 현장레미콘생산시설(B/P)설치 확대로 콘크리트 하자에 대한 책임한계 일원화 유도 - 레미콘 재료인 골재$\cdot$시멘트$\cdot$물을 공장에서 혼합하여 공급하는 현행 습식배합 대신에 물만을 현장에서 혼합하는 건식 배합방식을 도입 $\bullet$철강재$\cdot$철구조물의 품질을 보증하기 위하여 일정기술을 갖춘 공장에서만 제작토록 하는$\lceil$공장인증제$\rfloor$를 도입 - 제작시설과 품질관리 등을 심사하여 제작공장을 등급화하고 등급에 따라 철강재 등의 제작업무 범위를 차등화 $\bullet$시설물에 대하여도 시공업체가 제작공장을 등급화하고 등급에 따라 철강재 등의 제작업무 범위를 차등화 $\bullet$시설물에 대하여도 시공업체가 사후관리를 일괄 책임질 수 있도록 $\lceil$시공 및 유지관리 일괄계약제도$\rfloor$를 도입 - 대형교량$\cdot$소각로$\cdot$하수처리장 등 유지관리에 전문성이 요구되는 분야부터 시범적으로 도입 $\bullet$건설자재의 표준화$\cdot$정보화사업을 조속히 추진 5. 건설업체에 대한 지원 강화 $\bullet$일부 공공사업자의 경우 관행화되어 있는 대금일부의 어음 또는 채권지급방법을 단계적으로 축소 $\bullet$매월 감독이나 감리원의 기성확인에 의하여 시공자에게 공사대금을 직접 지급토록 하는 등 대금 지급절차를 간소화 6. 민간 건축물에 대한 안전확보 $\bullet$충실한 설계가 이루어지도록 제도를 개선 - 설계도서 작성기준을 제정하고 다중이용시설에 대하여는 건축심의단계에서 구조검토 등 설계심의를 의무화 $\bullet$대형다중이용시설에 대한 감리 강화 - 감리전문회사 수준의 감리체제로 전환하고 감리대가도 공공수준으로 인상하고 적용요율대로 지도$\cdot$감독 강화

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.509-517
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• 2020

This study evaluated the importance of technical characteristics in manufacturing street furniture using 3D printing technology to suggest the direction of development of high priority 3D printing technology. The importance was analyzed by the QFD, quantified by scores and the priority of the items was summarized. As a result, the 'output size', 'shrinkage of material', and 'output angle' were derived as technical elements that should be prioritized in development and research. For verification, the design of atypical street furniture was made into a large 3D printed output and the development direction was suggested by applying the technical elements of priority during the manufacturing process. Street furniture should be designed based on functionality and stability, as well as economic efficiency, productivity, and aesthetics. Therefore, the 'output size' ensured stability by minimizing the division of parts, and the 'contractability of materials' satisfied the aesthetic and productivity by minimizing the error of form. Finally, the 'output angle' was verified by improving the quality of the output and selecting an angle with efficient and structural stability through various output angles.

• Journal of the Korea Institute of Building Construction
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• v.20 no.6
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• pp.489-495
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• 2020

Whereas the control of the hydration heat in mass concrete has been important as the concrete structures enlarge, many conventional strategies show some limitations in their effectiveness and practicality. Therefore, In this study, as a solution of controling the heat of hydration of mass concrete, a method to reduce the heat of hydration by controlling the hardening of cement was examined. The reduction of the hydration heat by the developed Phosphate Inorganic Salt was basically verified in the insulated boxes filled with binder paste or concrete mixture. That is, the effects of the Phosphate Inorganic Salt on the hydration heat, flow or slump, and compressive strength were analyzed in binary and ternary blended cement which is generally used for low heat. As a result, the internal maximum temperature rise induced by the hydration heat was decreased by 9.5~10.6% and 10.1~11.7% for binder paste and concrete mixed with the Phosphate Inorganic Salt, respectively. Besides, the delay of the time corresponding to the peak temperature was apparently observed, which is beneficial to the emission of the internal hydration heat in real structures. The Phosphate Inorganic Salt that was developed and verified by a series of the aforementioned experiments showed better performance than the existing ones in terms of the control of the hydration heat and other performance. It can be used for the purpose of hydration heat of mass concrete in the future.

• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.292-302
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• 2008

The purpose of this study was to analyze the trophic structures and the energy flows in the lower reaches of the Nakdong River using the Ecopath model (Walter et al., 1997). The sampling and analyses were carried out at 6 sampling sites of the lower reaches of the Nakdong River on May and November in 2007. Total of 9 groups detritus, macrophytes, phytoplankton, zooplankton, zoobenthos, Cyprinus carpio, Hemibarbus labeo, Micropterus salmoides and other fishes were considered to assess the trophic relationship, energy flows and interactions among them in the study. As a result, it was concluded that the lower reaches of the Nakdong River was consisted of producers (Detritus, Macrophytes, Phytoplankton), primary consumers (Zooplankton, Zoobenthos, Cyprinus carpio, Hemibarbus labeo, Other fishes) and secondary consumer (Micropterus salmoides). The total system throughput was estimated at 2.7 kg m$^{-2}$ year$^{-1}$ including a consumption of 52%, exports of 9.1%, respiratory flows of 18.0% and flows into detritus of 20.9%. MTI (mixed trophic impacts) analysis demonstrated that Pseudobagrus fulvidraco had positive impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. On the other hand, other fishes had negative impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. Also, all the functional groups except detritus had a negative impact on themselves.

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.187-197
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• 2009

This paper presents a systematic approach for estimating fragility curves and damage probability matrices for different frequencies. Fragility curves and damage probability indicate the probabilities that a structure will sustain different degrees of damage at different ground motion levels. The seismic damages are to achieved by probabilistic evaluation because of uncertainty of earthquakes. In contrast to previous approaches, this paper presents a method that is based on nonlinear dynamic analysis of the structure using empirical data. This paper presents the probability of damage as a function of peak ground acceleration and estimates the probability of five damage levels for prestressed concrete (PSC) bridge pier subjected to given ground acceleration. At each level, 100 artificial earthquake motions were generated in terms of soil conditions, and nonlinear time domain analyses was performed for the damage states of PSC bridge pier structures. These damage states are described by displacement ductility resulting from seismic performance based on existing research results. Using the damage states and ground motion parameters, five fragility curves for PSC bridge pier with five types of dominant frequencies were constructed assuming a log-normal distribution. The effect of dominant frequences was found to be significant on fragility curves.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.276-290
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• 2020

Purpose: The construction history of domestic port facilities has been more than 100 years, and until recently, modern facilities have been continuously built and expanded. However, it is not easy to keep the required performance conditions at the time of initial construction due to changes in the marine environment and increase in volume. In particular, in the case of harbor structures that have a long service life, safety performance and function management are becoming very important due to the increase in the size of ships, the increasing frequency of use, and the increase in the scale of natural disasters. Method: Therefore, this study investigates the state change by structural type of port facilities and analyzes the rehabilitation activities and the history that contribute to the performance improvement and life extension activities. Result: Through this, we distinguished between performance improvement cost (CAPEX) and repair maintenance activity (OPEX) that can be used to establish port facility maintenance strategy, and suggested cost model that can be used to establish maintenance strategy. Conclusion: These studies are expected to contribute greatly to mid- to long-term investment decisions.