This study presents code-compliant seismic details by addressing dry mechanical splices for precast concrete (PC) beam-column connections in the ACI 318-19 code. To this end, critical observations of previous test results on precast beam-column connection specimens with the proposed seismic detail are briefly reported in this study, along with a typical reinforced concrete (RC) monolithic connection. On this basis, nonlinear dynamic models were developed to verify seismic responses of the PC emulative moment-resisting frame systems. As the current design code allows only the emulative design approach, this study aims at identifying the seismic performances of PC moment frame systems depending on their emulative levels, for which two extreme cases were intentionally chosen as the non-emulative (unbonded self-centering with marginal energy dissipation) and fully-emulative connection details. Their corresponding hysteresis models were set by using commercial finite element analysis software. According to the current seismic design provisions, a typical five-story building was designed as a target PC building. Subsequently, nonlinear dynamic time history analyses were performed with seven ground motions to investigate the impact of emulation level or hysteresis models (i.e., energy dissipation performance) on system responses between the emulative and non-emulative PC moment frames. The analytical results showed that both the base shear and story drift ratio were substantially reduced in the emulative system compared to that of the non-emulative one, and it indicates the importance of the code-compliant (i.e., emulative) connection details on the seismic performance of the precast building.

PURPOSES : Advancements in science and technology caused by industrialization have led to an increase in particulate matter emissions and, consequently, severity of air pollution. Nitrogen oxide (NOx), which accounts for 58% of road transport pollutants, adversely affects both human health and the environment. A test-bed was constructed to determine NOx removal efficiency at the roadside. TiO2, a material used to reduce particulate matter, was used to remove NOx. It was applied to a vertical concrete structure using the dynamic pressurized penetration TiO2 fixation method, which can be easily applied to vertical concrete structures. This study was conducted to evaluate the NOx removal efficiency of the dynamic pressurized-penetration TiO2 fixation method in a test-bed under real roadside conditions. METHODS : A test-bed was constructed in order to determine the NOx removal efficiency using the dynamic pressurized penetration TiO2 fixation method on the roadside. The dynamic pressurized-penetration TiO2 fixation method was applied by installing a vertical concrete structure. NOx was injected into the test-bed using an exhaust gas generator. By installing a shading screen, the photocatalytic reaction of TiO2 was suppressed to a maximum concentration of 1000 ppb along the roadside. The removal efficiency was evaluated by measuring NOx concentrations. In addition, illuminance was measured using an illuminance meter. RESULTS : From the results of the analysis of the NOx removal efficiency in the test-bed which the dynamic pressurized type TiO2 fixation method was applied to, an average removal efficiency ranging from 18% to 40% was achieved, depending on the illuminance. Similarly, according to the results of the evaluation of the NO removal efficiency, an average of removal efficiency ranging from 20% to 62% was achieved. Thus, the NOx removal efficiency increased when the illuminance was high. CONCLUSIONS : From the results of the experiment conducted, the efficiency of NOx removal per unit volume was obtained according to the illuminance of TiO2 concrete along an actual road. Field applicability of the dynamic pressurized-penetration-type TiO2 fixation method to vertical concrete structures along roads was confirmed.

Conditional spectra (CS) are applied to the seismic fragility assessment of a nuclear power plant (NPP) containment building for comparison with a relevant conventional uniform hazard response spectrum (UHRS). Three different control frequencies are considered in developing conditional spectra. The contribution of diverse magnitudes and epicentral distances is identified from deaggregation for the UHRS at a control frequency and incorporated into the conditional spectra. A total of 30 ground motion records are selected and scaled to simulate the probability distribution of each conditional spectra, respectively. A set of lumped mass stick models for the containment building are built considering nonlinear bending and shear deformation and uncertainty in modeling parameters using the Latin hypercube sampling technique. Incremental dynamic analysis is conducted for different seismic input models in order to estimate seismic fragility functions. The seismic fragility functions and high confidence of low probability of failure (HCLPF) are calculated for different seismic input models and analyzed comparatively.

최근 국내 지진 발생 빈도 및 강도가 증가함에 따라 지진 발생시 건물 주요 구조부에 대해서는 내진설계 및 내진 구조기술이 적용되어 지진에 대비하고 있으나, 비구조 요소인 커튼월과 창호에 대해서는 내진에 대비한 충분한 고려가 이루어지지 못하고 있다. 본 연구에서는 동적 내진성능 기준을 만족할 수 있는 커튼월을 개발하기 위해 동적 지진파 인가 시 커튼월이 파손 없이 대응 가능한 지진 변위 대응 패스너를 적용하여 동적 내진성능실험을 통해 이를 규명하고자 한다. 동적 내진성능실험을 수행한 결과, 본 연구에서 제시한 3축 이동형 패스너를 활용한 커튼월이 실제 지진파에 대응 가능하다는 것을 확인할 수 있었다.

본 연구에서는 동맥스핀라벨링을 이용하는 비 조영증강 기법인 4D TRANCE으로 동정맥기형 환자를 진단함에 있어 기존에 사용하고 있는 4D TRAK과 조영증강 3D TOF으로 얻는 진단적 정보의 재현성과 유용성을 알아보고자 하였다. 연구방법 은 동정맥기형 추적검사를 하는 환자 14명을 대상(남자 4명, 여자 10명)으로 하여 뇌혈관 영상을 각각 4D TRANCE, 4D TRAK, 조영증강 3D TOF를 순서로 획득하였다. 영상의학과 전문의 2명이 3 영상의 진단적 평가와 영양동맥(feeding artery, FA)과 배출정맥(draining vein, DV)을 비교 평가하였고, 동일한 부위의 병소(nidus)와 내경동맥에 대한 대조도 잡음비를 비교 분석하였다. 정성평가는 4D TRANCE는 진단적 정확도 3.93(3.89~4.04), FA 3.75(3.55~3.95), DV 1.96(1.77~2.16) 으로 모든 구간에서 4D TRAK과 비교하여 통계적으로 유의하였으나(p＜0.001), 유일하게 DV에서 유의하지 않았다. 정량 분석에서는 4D TRANCE와 3D TOF의 대조도 잡음비에 따른 독립표본 T검정 결과, 조영증강되는 병소에서는 4D TRANCE가 3D TOF에 비해 15.50의 차이로 높았으며, 통계적으로 유의하였다. 본 연구는 동정맥기형 추적검사에 대해 4D TRANCE는 4D TRAK보다 다소 저하된 영상품질을 보여주었으나, 3D TOF와 비교했을 때 혈관 해부학 및 혈류역학 정보를 제공하기 때문에 더 신뢰할 수 있는 정보를 제공하여 임상 영상 평가에 유용하게 사용할 수 있다.

PURPOSES : For compaction control on the subgrade layer, the simple and economical test DCPT (Dynamic Cone Penetrometer Test) is being applied to the Korea Pavement Design Guide. However, compaction control is now difficult and to conduct in the field and is not performed in practice because the compaction degree is evaluated via the field density test as a pretreatment step when the compaction management process is evaluated by DCPT at the same time. Therefore, this study tried to propose a method considering an evaluation for the compaction degree using DCPT, via laboratory tests and field tests. METHODS: The in-situ DCPT tests were conducted according to the types of subgrade soils in the field. Afterward, the field density tests for the compaction degree (R) of field samples and the experiments using DCPT were performed simultaneously in a self-made test container in the lab. RESULTS: Through the DCPT test, compaction degree evaluation from the correlations proposed in this study was determined to be possible. Additional field tests could verify the proposed correlations between compaction degree with DCPT PR on the subgrade. CONCLUSIONS: For the evaluation of the subgrade compaction degree using dynamic CPT, the correlations between compaction degree and DCPT PR on the subgrade layer are proposed from laboratory tests and field tests using DCPT and field density tests.

Recently, the occurrence frequency of earthquake has increased in Korea, and many cultural assets have been damaged. Cheomseongdae is a valuable cultural assets that must be preserved historically and culturally. But, the masonry structure such as Chemseongdae is vulnerable to lateral forces. Therefore, in this study, structural modeling and dynamic analysis are performed to reflect the ground state and structural form of Cheomseongdae. Also, discrete element analysis technique is applied and dynamic behavior characteristics are analyzed according to earthquake load. For this purpose, displacements and stresses according to locations are reviewed and then swelling and distortion are analyzed.

화력발전소 구조물 중 하나인 보일러 강구조물은 물탱크가 올라가게 되는 중요한 설비지만 그 중요성이 비해 지진에 대한 안전성 평가에 대한 연구가 미비하다. 본 연구에서는 취약도 곡선을 도출하고자 16개의 지진파에 12개의 PGA값을 선정하고 포 항지진을 포함해 총 200회의 동적 비선형 해석을 수행하였다. 강재의 인장, 압축응력과 강구조물의 상대변위를 측정하였다. 강재 재료적 특성의 경우 변형은 발생하였으나 파괴는 발생하지 않았고, 상대변위의 경우 한계점에 못 미치는 변위가 발생하였다. 취약도 곡선 도출결과 국내의 지진구역 구분 및 지역계수를 기준으로 강재의 재료적 변형(400MPa)에서는 인장이 38%, 압축이 62.5%로 변형이 발생하였고, 상대변위는 0%의 확률로 한계점을 넘었다. 이러한 보일러 강구조물에 대한 취약도 곡선은 대상구조물에 대한 한 계상태를 판별하는 정량적 근거와 지진에 대한 안전설계시 활용될 수 있다.

Yangjindang house, which is located in Sang-ju province of South Korea, is one of the special Hanok structures dated back to Joseon dynasty. This study aims to examine structural safety of the Yangjindang wood frame building considering dynamic parameters such as the natural frequency and damping ratio. The numerical model of the wood frame building is implemented using Midas Gen, especially the wood joint where column and beam were connected. The behavior of the actual frame building was compared with the modeling results. In addition, structure responses such as shear force, axial force, flexural moment and deflections were calculated and compared with the allowable limits. Numerical results show that, generally, despite of some local members shear failure, Yangjindang’s structural response does not exceed the limitation according to current standards.

본 연구는 간편화된 소성 접선 곡선을 적용하여 노측용 가드레일 시스템의 충격 성능을 평가하기 위한 유한요소 충돌해석을 수행하였다. 충돌해석은 Cowper-Symond 모델을 적용하여 변형률 속도 영향에 대한 결과의 정확성을 향상시켰다. 수치 해석 결과는 소성 접선 곡선을 고려한 향상된 모델의 중요성을 보여준다. 다양한 매개변수에 대한 해석 결과는 서로 다른 모델에 대하여 동적 응답 및 탑승자 안전지수를 중심으로 비교 검증하여 도출하였다.

이 연구는 운항자가 항해 중 위험을 느끼는 고정 및 이동 물표에 대한 해상교통위험성평가에 대한 것이다. 이를 위해 선박 길이와 속력, 선박조종성능이 고려된 동적선박영역을 기초로 한 충돌위험평가식을 구하였다. 특히, 동적선박영역과 충돌위험평가식을 하이브리드 결합하여 자선의 크기, 속력 등의 영향을 정량적으로 지표화한 항해위험성평가모델을 검토 및 개선하고자 한 것이다. 기존 항해위험성평가 모델에 적용이 부족한 속장비(speed length ratio) 즉, 선박의 길이와 속력에 대한 비가 고려된 새로운 형태의 해상교통위험성평가 모델을 제안하고자 한다. 그 결과 무차원 속력 즉, 속장비가 클수록 CJ 값이 크며, CJ 값은 속장비에 의해 잘 표현되고 있다. 또한, 속장비가 크면 속장비가 작은 경우보다, 보다 먼 거리에서부터 [주의], [경계], [위험] 또는 [매우위험]상태에 도달한다. 이 연구의 결과는 위험항로 회피 또는 최적항로 구축, 방파제폭이나 교량경간 등을 포함한 항로나 항만개발, 연안항해용 안전해도 개발 및 향후 자율운항선박과 같은 스마트선박의 운항 중 충돌방지와 최적항로 선정에 자료로 사용될 수 있을 것이다.

계면동전위(electrokinetic potential)로 불리는 제타전위(zeta potential)란 표면 전하적 특성을 정량화한 값으로, 전기동역학적 현상으로 인하여 발생하는 전기적 유동층을 통과하는 전위차를 말한다. 이러한 제타전위는 표면화학분야의 기초, 응용적인 연구에서 중요하다. 제타전위는 용액 내에서 표면 전하 특성 정보를 얻을 수 있다. 이를 측정하는 방법으로는 계면동전위효과(electrokinetic effects)를 이용한다. 현재 위 효과를 이용하여 제타전위 측정 기기로 측정이 쉽게 가능하고, 많은 연구가 진행되어왔다. 본 연구에서는 계면동전위의 원리, 측 정, 결과 등을 제시하면서 분리막 표면 특성평가에 관한 내용을 제시하였다.

Dynamic numerical simulation of pile-supported slab track system embedded in a soft soil and embankment was performed. 3D model was formulated in a time domain to consider the non-linearity of soil by utilizing FLAC 3D, which is a finite difference method program. Soil non-linearity was simulated by adopting the hysteric damping model and liner elements, which could consider soil-pile interface. The long period seismic loads, Hachinohe type strong motions, were applied for estimating seismic respose of the system, Parametric study was carried out by changing subsoil layer profile, embankment height and seismic loading conditions. The most of horizontal permanent displacement was initiated by slope failure. Increase of the embedded height and thickness of the soft soil layer leads increase of member forces of PHC piles; bending moment, and axial force. Finally, basic guidelines for designing pile-supported slab track system under seismic loading are recommended based on the analysis results.

Current seismic design provisions such as ASCE 7-10 provide criteria for selecting ground motions for conducting response history analysis. This study is the sequel of a companion paper (I – Ground Motion Selection) for assessment of the ASCE 7-10 criteria. To assess of the ASCE 7-10 criteria, nonlinear response history analyses of twelve single degree of freedom (SDF) systems and one multi-degree of freedom (MDF) system are conducted in this study. The results show that the target seismic demands for SDF can be predicted using the mean seismic demands over seven and ten ground motions selected according to the proposed method within an error of 30% and 20%, respectively

For estimating the seismic demand of buildings, most seismic design provisions permit conducting linear and nonlinear response history analysis. In order to obtain reliable results from response history analyses, a proper selection of input ground motions is required. In this study, an accurate algorithm for selecting and scaling ground motions is proposed, which satisfies the ASCE 7-10 criteria. In the proposed algorithm, a desired number of ground motions are sequentially scaled and selected from a ground motion library without iterations.