• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.705-714
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• 2003

Even though Korean peninsula is located in regions of moderate seismic risks, current seismic design provisions of the roadway bridge design code have adopted the AASHTO code which is based on the requirements for high seismic regions. The objective of this research is to investigate the seismic performance of circular reinforced concrete (RC) bridge piers with limited ductility, which may be desirable in low or moderate seismic regions, such as in Korea. Four test specimens were designed and constructed. The reference specimen was designed with longitudinal steel ratio as 1.01% and the confinement reinforcement ratio as 0.13% without considering earthquake, and three other test specimens were designed in accordance with a limited-ductility concept as 0.3% for the confinement steel ratio. This confinement ratio is 0.32 times of minimum lateral reinforcement specified in current seismic design provisions, and 2.3 times of lateral reinforcement required in nonseismic design provisions. The pseudo-dynamic test was carried out to evaluate the seismic performance of full-scale specimens in size of 1.2m diameter and 4.8m height. Judging from the experiment, the reference specimen was not satisfactory for the demand displacement ductility ${\mu}$=5.0, but three limited-ductility specimens appeared to have the displacement ductility of more than 5.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.789-795
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• 2002

To evaluate the bind rate and behavior of two types chloride ion-one is the chloride ion added in mixture when un-washed sea sand is used as fine aggregate, one is the chloride ion admitted in the new version of concrete standard specification, pore solution extracted in cement paste were analyzed. The results are follow. 1 As passing the time, the chloride concentration in the pore solution decreases with the Increase in the chloride content absorbed by the hydrate products. As compared with chloride contents in mixing water, the bound ratio of chloride at 49 days is 64∼90％. 2. The bound ratio of chloride in cement paste considering evaporable water as pore solution is obtained. In case of Pl∼P3(added chloride content wt of cement 0.046∼0.16 ％), the bound ratio of chloride is 91.8∼93.5 ％. P4(added chloride wt of cement 0.3％) is 89.1％, but P5(added chloride wt of cement 0.617％) bound is only 77％. 3. The bound ratio of chloride to wt of cement is 0.015∼0.475％ with adding chloride. In case chloride added over 0.091 ％ wt of cement, the bound chloride content increases 1.7∼1.8 times in spite of added chloride increase twice. The bound ratio of chloride to wt of cement decreased with the increase in the chloride content. 4. The more increase added chloride content, the more increase the bound ration of chloride. But the absolute value of chloride content in pore solution increased.

• Journal of Korean Society of Steel Construction
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• v.20 no.3
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• pp.399-407
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• 2008

The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on temperature variables despite the break of the pin tail. In this study, the tension of torque shear bolts were compared with two types of high-strength hexagon bolts by temperature parameters from ${-10^{\circ}C}$ to ${50^{\circ}C}$. Torque shear bolts showed that the average clamping force increased to 20kN as the temperature increased. In case of galvanized high-strength hexagon bolts, the average clamping forces at $0^{\circ}C$, $20^{\circ}C$, $50^{\circ}C$ were recorded over standard bolt tension, 178kN, and the worst standard deviation was 50kN. In case of high-strength hexagon bolts, ave rage clamping forces increased as the temperature went up, and the worst standard deviation was 33kN lower than that of galvanized high-strength hexagon bolts. As for the turn-of-the-nut method, at nut rotation of ${90^{\circ}}$, two types of high-strength hexagon bolts did not met the intended design bolt in tension, 162kN.it is neccessary to re-evaluate the range of turn of nut, ${120^{\circ}{\pm}30^{\circ}}$.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.111-122
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• 2005

The data on the pile load tests performed on 35 large drilled shafts are analyzed to investigate the load-settlement characteristics of large drilled shafts embedded in bed rocks. Generally, the settlement of large drilled shafts embedded in bed rocks is too small to determine the ultimated load with application of the regulation in design code for either the total settlement or the residual settlement. Therefore, to determine the yield load of large drilled shafts embedded in bed rocks, p(load)-logS (settlement) curve method, which has been proposed originally for the driven pile, was applied to the investigation on the data of the pile load tests. This technique shows that the yield load can be determined accurately and easily rather than other conventional techniques such as P-S, logp-logS, S-logt, and P-S curve methods. An empirical equation is proposed to represent the relationship between pile load and settlement before the yield loading condition. And the settlement of piles was related with the depth embedded in rock as well as rock properties. Based on the investigation on the data of pile load tests, the resonable regulations f3r both the total settlement and the residual settlement are proposed to determine the yield load of large drilled shafts embedded in bed rocks.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.49-58
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• 2008

Generally, steel corrosion occurs in concrete structures due to carbonation in down-town area and underground site and it propagates to degradation of structural performance. In general diagnosis and inspection, only carbonation depth in sound concrete is evaluated but unsound concrete such as joint and cracked area may occur easily in a concrete member due to construction process. In this study, field survey of carbonation for RC columns in down-town area is performed and carbonation depth in joint and cracked concrete including sound area is measured. Probability of durable failure with time is calculated through probability variables such as concrete cover depth and carbonation depth which are obtained from field survey. In addition, service life of the structures is predicted based on the intended probability of durable failure in domestic concrete specification. It is evaluated that in a RC column, various service life is predicted due to local condition and it is rapidly decreased with insufficient cover depth and growth of crack width. It is also evaluated that obtaining cover depth and quality of concrete is very important because the probability of durable failure is closely related with C.O.V. of cover depth.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.87-96
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• 2023

There are a lot of difference between the surface settlement and the differential settlement measured at the Busan New Port, where the dredged and reclaimed clay layer exists and below the clay is originally thickly distributed. To find the cause and solution of this, the actual conditions of each differential settlement used for the soft ground improvement, characteristics, installation method, measurement frequency, measurement data management, and data analysis of each type were considered. In the deep soft ground improvement work where large deformation occurs, the bending deformation of the screw-type differential settlement gauge is less than that of other types of measuring instruments, so there is less risk of loss, and the reliability of data is relatively high as the instruments are installed by drilling for each stratum. Since the greater the amount of high-precision settlement measurement data, the higher the settlement analysis precision. It is necessary to manage with higher criteria than the measurement frequency suggested in the standard specification. For the data management of the differential settlement gauge, it is desirable to create graphs of the settlement and embankment height of the relevant section over time, such as surface, differential, and settlement of pore water pressure gauge for each point. In the case of multi-layered ground with different compression characteristics, it is more appropriate to perform settlement analysis by calculating the consolidation characteristics of each stratum using a differential settlement data.

• Korean Journal of Heritage: History & Science
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• v.49 no.2
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• pp.56-69
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• 2016

Flame resistant treatment has been applied since 1973 for fire prevention in historical wooden buildings, but several problems, such as whitening and discoloration are constantly occurring in some Dancheong, in spite of evaluation criteria. It is supposed that these phenomena are caused by the stability issue of flame retardant, Dancheong production methods, the residue of chemicals, which were applied in the past, building location environments, etc., but no evaluation and cause inspection has been performed. Therefore, this study aims to verify the effect of flame retardant on Dancheong by producing Pseudo-samples and setting spatial and temporal environment conditions. Pseudo-samples of Dancheong were produced using three methods; the method specified in the Standard Specification of Properties; the method, which is generally used in the site and the traditional method. For different environment conditions of pseudo-samples, the areas were classified into a coastal area and an inland area and the places were classified into a sunny place and a wetland. After applying a flame retardant, annual variations were inspected for 12 months and change aspects were observed through scan and regular observation. In annual variation inspection, various variations like whitening, decolorization, dissolution and exfoliation were found and especially, whitening was most dominant. When the effect of flame retardant depending on the production methods was analyzed, whitening occurred in all the three production methods. It is supposed that this is because calcium(Ca) was contained in the coloring material of each production method and it reacted with phosphorous(P) of flame retardant. When the effect of flame retardant depending on the environment conditions was analyzed, whitening occurred more in the coastal area than in the inland area and it reduced in the building in a sunny place, which was constructed using the traditional method. It is supposed that this results from the humidity change and the difference of glue used in each production method. In conclusion, for using a flame retardant containing phosphorous(P), there is a need to check if calcium components including Oyster Shell White were used in Dancheong in advance and to conduct various preliminary studies on place conditions and Dancheong construction conditions.

• 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