• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.1-12
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• 2019

The purpose of this study is to enhance the seismic performance of exposed column-base plate weak-axis connections for small-sized steel buildings. According to the site inspection for the small-sized building construction, the arbitrary connection details in steel buildings have been applied at the job site, which is considered to be insufficient to guarantee structural safety and stability considering the increased seismic risk in Korea. Therefore, a series of test programs had been done to develop enhanced connection details in order to ensue the adequate seismic stability and safety of small-sized steel buildings. From the test results, It was found that the exposed column-base plate weak-axis connections commonly used in Korea shows very poor seismic behavior due to the "Rocking" phenomena caused by the residual plastic deformation of anchor bolts between anchor plate and concrete. A series of hysteretic tests for finding that solution were conducted to reduce the "Rocking" phenomena of the column-base plate connections, and local buckling of webs in H-column. Finally the enhanced stable seismic behavior was obtained by reinforcing at least 8 anchor bolts with good bonding strength and stiffeners to the webs in H-column.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.19-25
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• 2003

산업현장에서 에어를 사용함으로써 나타나는 소음에 작업자가 노출되면, 그 소음 강도에 따라 작업자로 하여금 건강장애, 소음성난청 등을 유발하는 여러 가지 문제점이 심각하게 나타나고 있는 실정이다.(중략)

• Fire Science and Engineering
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• v.25 no.2
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• pp.107-113
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• 2011

This paper presents the results of artificially accelerated aging characteristics of the rate of rise spot type heat detectors. This experiment carried out to investigate the detector's operating characteristics when a fire was broken out or the regular tests were performed. The result showed that the delay of operating time or no-operation of heat detector which was made by company B and used in the field for 5 years may be occurred even at the $100^{\circ}C$. This result is due to the leakage of inflated air from heat chamber. However the operating display LED was not out of order, even if the temperature was increased up to $160^{\circ}C$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.421-435
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• 2012

Rock excavation (removal) tests are performed with effective parameters using an abrasive waterjet. For verification of the field rock excavation capabilities, the removal performance and level of efficiency are analyzed for hard granite rock in terms of the water pressure, exposure time of the jet, and the standoff distance. In particular, experimental tests are performed with a long standoff distance required condition in the real excavation field. The rock removal performance level changes according to the rock properties. In this study, various rock specimens are used and P-wave velocities are measured in order to determine the correlation between the removal performance and the P-wave velocity. As a result of the experimental study, the effect of waterjet parameters on rock removal is analyzed.

• 보존과학연구
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• s.33
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• pp.69-83
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• 2012

Field experiments for Conservation damage on selected spots were carried out prior to direct conservation treatments for Bangudae Petroglyphs in Ulsan. It was found that there is a big difference in treatment effects according to the treatment technique and application rather than on the treatment material use. Based on the results of this study, a plan for the conservation treatment of Bangudae Petroglyphs will be suggested by providing new materials and application techniques for cracks, adhesive application and consolidation by conducting artificial weathering tests and continued monitoring.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.17-20
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• 2010

기존의 무량판 구조와 동일한 이방향 슬래브구조인 TVS(two-way void slab)공법은 구조적 하중지지 성능이 불필요한 슬래브 단면상의 중앙부 콘크리트를 제거하여 슬래브의 자중을 줄이고 무량판 구조의 단점을 보완하여 장점을 극대화시킨 구조형식이다. 그러나 이러한 장점을 보유한 공법을 현장적용하기 위해서는 내화성능평가를 통해 화재안전성을 확보하여야 하므로, 이에 대한 화재 실증실험을 수행하여 현장적용을 위한 최소 요구내화 시간에 따른 내화성능 확보방안의 도출이 제시되어야 한다. 이에 본 연구에서는 TVS공법의 실제 스팬길이로 슬래브 피복두께에 따른 화재거동 영향성 분석을 위하여 화재실험을 수행하였다. 하중조건은 고정하중과 적재하중을 고려하여 실험체에 등분포 조건으로 사전재하하였으며, 표준화재조건으로 재하가열 실험을 수행하였다. 슬래브의 화재가열 노출면으로부터의 깊이별 온도변화와 처짐변형 특성을 측정하였으며, KS F 2257-1 평가기준에 의거하여 슬래브의 내화성능을 평가하였다. 실험결과 피복두께 50 mm를 확보할 경우, EPS중공체로 제작한 실험체의 경우 약 2시간정도의 내화성능을 확보할 수 있는 것으로 나타났다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.421-424
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• 2010

최근 노후한 기존 구조물의 교체 및 건물 증축으로 인하여, 도심지 내 공사 현장 및 주변 지반에 매설된 지중 배관은 차량 이동 하중 및 건설 장비 하중 등의 진동에 노출이 되어있는 실정이다. 이러한 장비하중이 매설배관에 미치는 영향을 분석, 예측하기 위하여 실증 실험 결과를 토대로 모델을 검증하고 수치해석을 수행하였다. 그 결과 최대 발생 응력은 외관은 $270^{\circ}$에서, 내관은 $180^{\circ}$에서 발생 하였으며, 이는 폴리우레탄 보온재의 하중 분산 효과로 설명 할 수 있다.

• Journal of the Society of Disaster Information
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• v.9 no.1
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• pp.22-29
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• 2013

Warm mix asphalt(WMA), which is produced at lower temperatures than hot mix asphalt, has advantages in reductions of fuel consumption and greenhouse-gas emission. In this study, field tests such as skid resistance, rutting(permanent deformation), and roughness were conducted for analysis of long-term field performance of modified warm mix asphalt pavement. Skid resistance after 20 months represents the result similar to initial performance results but rutting and roughness decreased somewhat depending on the period of performance. Measurement results of permanent deformation and roughness could be acceptable because measured pavement location is bus lane that a lot of buses pass and stop. There were no cracks after 11 months, but some minor cracks were observed after 20 months. These results were influenced by increased crack resistance due to fiber addition.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.812-816
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• 2012

본 논문은 산사태 감지 및 붕괴예측을 위한 현장에 USN(Ubiquitous Sensor Network)을 적용한 실시간 모니터링 시스템 모델을 개발하였다. 이 시스템의 성능을 검증하기 위해 USN기반의 상시모니터링시스템모델을 제작하고 실험적 평가를 수행하였다. 성능평가는 지표변위 센서모듈 동작특성 실험적 평가, USN은 Data 수집 전송 효율성 실험적 평가, 개발한 상시감시모니터링 프로그램 동작성능 실험적 평가 등을 수행하였다. 성능평가 결과 지표변위 측정센서모듈은 변위각도에 일치성을 확인하고, USN은 지표변위 센서모듈로부터 측정된 Data를 상시모니터링시스템에 오류 없이 전송되는지를 확인하였으며, 개발한 상시모니터링 프로그램 동작기능은 실시간 모니터링 그래프, 임계동작 알고리즘, 위험성 통보 문자서비스(SMS)기능, 알람서비스기능, 현장 감시카메라 등 동작기능의 우수성을 실험으로 증명하였다. 따라서 본 연구에서 개발된 산사태 감지 예측을 위한 USN기반 실시간 모니터링 시스템 모델은 산사태위험성노출 지역에 원격 실시간 모니터링 시스템으로 널리 사용될 것으로 사료된다.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.43-53
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• 2008

Because the torque control method, which is also caled the clamping method in domestic construction sites, is affected by a variation of the torque coefficient, quality control of the torque coefficient is essential. This study was focused to evaluate the effects of several environmental factors and errors when installing bolts while tightening high-strength bolts. Conditioning environmental parameters include wet, rusty and exposure-to-air-only conditions. In addition, because of errors in workability such as instalation of two washers, upset washers are selected. During the tests, torque, torque coefficient, tension and angle of nut rotation were obtained using a bolt testing machine. Test specimens of four types of bolts (High-Strength Hexagon bolt on KS B 1010, Torque Shear Bolt on KS B 2819, High-Strength Hexagon bolt coated with zinc, and ASTM 490 bolt) were recomended. Based on test results, the tightening characteristics subjected to environmental parameters were investigated and compared with the results in normal condition.