• Earthquakes and Structures
• /
• 제20권3호
• /
• pp.337-351
• /
• 2021

On September 12, 2016, the Gyeongju earthquake occurred in the south-eastern region of the Korean peninsula. The event was ranked as the largest magnitude earthquake (=5.8) since instrumental recording was started by the Korean Metrological Administration (KMA) in 1978. The objective of this study is to provide information obtained from the 2016 Gyeongju earthquake and to propose a procedure estimating seismic risk of a typical old RC building for past and potential earthquakes. Ground motions are simulated using the point source model at 4941 grid locations in the Korean peninsula that resulted from the Gyeongju earthquake and from potential future earthquakes with the same hypocenter considering different soil conditions. Nonlinear response history analyses are conducted for each grid location using a three-story gravity-designed reinforced concrete (RC) frame that most closely represents conventional old school and public buildings. Then, contour maps are constructed to present the seismic risk associated with this building for the Gyeongju earthquake and potential future scenario earthquakes. These contour maps can be useful in the development of a mitigation plan for potential earthquake damage to school and public buildings at all grid locations on the Korean peninsula.

• 한국터널지하공간학회 논문집
• /
• 제19권1호
• /
• pp.11-27
• /
• 2017

서울시 등의 국내 주요 도심은 지역적 팽창에 따라 도로망 체계가 급격하게 발전하였고 도시민이 안락하고 풍요로운 생활을 영위하도록 전력, 통신, 상수도, 하수도, 냉 난방관로, 가스관 등이 무분별하게 개별 매설되었으며 비효율적으로 개별 관리되고 있다. 국토계획법에서는 Life-Line을 공동 수용함으로써 도로의 반복 굴착을 줄이고 도시 미관의 개선, 포장 내구성 향상에 따른 주행성능 향상 그리고 원활한 교통소통 등을 기대하는 도시계획 시설물로 공동구를 정의하고 있다. 최근 기존 도심지의 재정비 측면에서 쾌적한 도시공간 조성, 지하공간 이용 효율과 도로관리 효율 향상, 지진 및 도로함몰에 대한 재난안전성, 스마트 그리드와 전기자동차 보급과 같은 미래 생활환경 변화에 대한 신속한 대응 등을 기대할 수 있는 기존 도심지의 공동구 설치 필요성이 증가하고 있으나 국내에 설치된 모든 공동구는 신도시 개발에 따라 계획된 Life-Line을 모두 수용하도록 설치한 개착식 공동구 형태이다. 기존 도심지에서는 현재 가동중인 모든 Life-line을 모두 수용할 수 없으므로 도심지 유형별 공동구 설치 타당성 평가시스템을 활용한 설계용량 최적화 등의 새로운 연구가 필요하다. 본 연구는 신도시 공동구를 탈피하고 기존 도심지를 대상으로 평가지표에 의한 정량적 평가모델을 제시 하는 등 유형별 타당성 평가시스템을 세분화하며 정량적 평가시스템의 구현이 가능한 프로그램을 개발해 궁극적으로 도심지 공동구 활성화에 기여하고자 한다.

• Geomechanics and Engineering
• /
• 제4권3호
• /
• pp.173-190
• /
• 2012

With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

• 한국간호교육학회지
• /
• 제4권1호
• /
• pp.7-14
• /
• 1998

The use and need of health and nutrition information on the PC communication and internet among university students at Chungbuk area were investigated. The data from 167 students from two different universities were collected and analyzed from March to May, 1998. The results are as follows. 1. Male students were 27.5% and female students were 72.5%. 2. Sixty percent and 74.7% of the students had ever used PC communication and internet, respectively. Higher proportions of male students had experiences in PC communication and internet use than fe male students. The main reasons to use PC communication and internet were 1)to obtain information and knowledge(67.4%) 2)to enjoy(10.5%), 3)to make friends or to talk(5.3%) 3. About 40% of the experienced students of the PC communication of internet obtained health or nutrition information. However, only 25% of the experienced students obtained the nutrition information from the internet. Only 10% of the students agreed that the information from the PC communication and internet was very useful. The reasons not to use the information from the PC communication and internet were 'lack of expertise of the information' and 'long response time'. Many students thought that the information provided through the computer should be improved in terms of variety and applicability to the real situation. 4. Among the 33 topics of the health and nutrition information given on the questionnaire, both male and female students had the greatest interest in stress management. The next topics in which female students had interests were diet for weight control, health problems related to menstration, dietary assessment, and cancer prevention. In male students, dietary assessment, infant nutrition management, hypertention diet were the main interests. On the basis of these results an information system on health and nutrition management during the lifecycle for Korean women will be constructed on the internet.

• Earthquakes and Structures
• /
• 제8권4호
• /
• pp.859-887
• /
• 2015

Structural health monitoring (SHM) has gained in popularity in recent years since it can assess the performance and condition of instrumented structures in real time and provide valuable information to the asset's manager and owner. Operational modal analysis plays an important role in SHM and it involves the determination of natural frequencies, damping ratios and mode shapes of a constructed structure based on measured dynamic data. This paper presents the operational modal analysis and seismic response characterization of the Tsing Ma Suspension Bridge of 2,160 m long subjected to different earthquake events. Three kinds of events, i.e., short-distance, middle-distance and long-distance earthquakes are taken into account. A fast Bayesian modal identification method is used to carry out the operational modal analysis. The modal properties of the bridge are identified and compared by use of the field monitoring data acquired before and after the earthquake for each type of the events. Research emphasis is given on identifying the predominant modes of the seismic responses in the deck during short-distance, middle-distance and long-distance earthquakes, respectively, and characterizing the response pattern of various structural portions (deck, towers, main cables, etc.) under different types of earthquakes. Since the bridge is over 2,000 m long, the seismic wave would arrive at the tower/anchorage basements of the two side spans at different time instants. The behaviors of structural dynamic responses on the Tsing Yi side span and on the Ma Wan side span under each type of the earthquake events are compared. The results obtained from this study would be beneficial to the seismic design of future long-span bridges to be built around Hong Kong (e.g., the Hong Kong-Zhuhai-Macau Bridge).

• Structural Engineering and Mechanics
• /
• 제60권6호
• /
• pp.1021-1038
• /
• 2016

Considerable part of reinforced concrete building has suffered from destructive earthquakes in Turkey. This situation makes necessary to determine nonlinear behavior and seismic performance of existing RC buildings. Inelastic response of buildings to static and dynamic actions should be determined by considering both flexural plastic hinges and brittle shear hinges. However, shear capacities of members are generally neglected due to time saving issues and convergence problems and only flexural response of buildings are considered in performance assessment studies. On the other hand, recent earthquakes showed that the performance of older buildings is mostly controlled by shear capacities of members rather than flexure. Demand estimation is as important as capacity estimation for the reliable performance prediction in existing RC buildings. Demand estimation methods based on strength reduction factor (R), ductility (${\mu}$), and period (T) parameters ($R-{\mu}-T$) and damping dependent demand formulations are widely discussed and studied by various researchers. Adopted form of $R-{\mu}-T$ based demand estimation method presented in Eurocode 8 and Turkish Earthquake Code-2007 and damping based Capacity Spectrum Method presented in ATC-40 document are the typical examples of these two different approaches. In this study, eight different existing RC buildings, constructed before and after Turkish Earthquake Code-1998, are selected. Capacity curves of selected buildings are obtained with and without considering the brittle shear capacities of members. Seismic drift demands occurred in buildings are determined by using both $R-{\mu}-T$ and damping based estimation methods. Results have shown that not only capacity estimation methods but also demand estimation approaches affect the performance of buildings notably. It is concluded that including or excluding the shear capacity of members in nonlinear modeling of existing buildings significantly affects the strength and deformation capacities and hence the performance of buildings.

• Clinical and Experimental Reproductive Medicine
• /
• 제48권2호
• /
• pp.163-173
• /
• 2021

Objective: This study aimed to characterize a validated model for predicting oocyte retrieval in controlled ovarian stimulation (COS) and to construct model-based nomograms for assistance in clinical decision-making regarding the gonadotropin protocol and dose. Methods: This observational, retrospective, cohort study included 636 women with primary unexplained infertility and a normal menstrual cycle who were attempting assisted reproductive therapy for the first time. The enrolled women were split into an index group (n=497) for model building and a validation group (n=139). The primary outcome was absolute oocyte count. The dose-response relationship was tested using modified Poisson, negative binomial, hybrid Poisson-E_max, and linear models. The validation group was similarly analyzed, and its results were compared to that of the index group. Results: The Poisson model with the log-link function demonstrated superior predictive performance and precision (Akaike information criterion, 2,704; λ=8.27; relative standard error (λ)=2.02%). The covariate analysis included women's age (p<0.001), antral follicle count (p<0.001), basal follicle-stimulating hormone level (p<0.001), gonadotropin dose (p=0.042), and protocol type (p=0.002 and p<0.001 for short and antagonist protocols, respectively). The estimates from 500 bootstrap samples were close to those of the original model. The validation group showed model assessment metrics comparable to the index model. Based on the fitted model, a static nomogram was built to improve visualization. In addition, a dynamic electronic tool was created for convenience of use. Conclusion: Based on our validated model, nomograms were constructed to help clinicians individualize the stimulation protocol and gonadotropin doses in COS cycles.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제34권3호
• /
• pp.215-234
• /
• 2020

AI 시대의 함께 교육에서도 AI 활용의 필요성이 제기된다. 본 연구의 목적은 예비수학교사가 인식하는 미래 수학교육에서 AI의 필요성과 AI 활용에서 교사의 역할을 조명하는 것이다. 연구 결과, 교수 측면에서 예비교사들은 학교 수학에 AI 활용이 시대적 요구이며, 다양한 유형의 수업 구현과 정확한 지식 및 정보를 전달할 수 있지만, 인지적·감정적 상호작용에 한계가 있다고 하였다. 학습 측면에서 AI는 개별화 학습을 제공하고, 학교 수업 외 보충학습에 활용할 수 있고, 학습 흥미를 자극할 수 있지만, 학생들의 주체적 사고 능력을 저해할 수 있다고 하였다. 평가의 측면에서 AI는 객관적이고 공정하며 교사의 업무를 감소할 수 있지만 서·논술형 문항과 과정 중심 평가에서 한계가 있다고 하였다. AI 활용에서 예비교사들이 생각하는 교사의 역할은 수업, 감정적 상호작용, 비정형화된 평가, 상담이었고, AI의 역할은 개별화 학습, 기계적 학습, 정형화된 평가와 행정 업무로 나타났다.

• 대한토목학회논문집
• /
• 제39권6호
• /
• pp.743-750
• /
• 2019

하천을 수원으로 하는 상수도 시설은 강수량 및 하천 유량과 같은 모니터링 설비가 없는 곳이 대부분이며, 갈수기 등 하천 유량 감소기에도 취수량 조절과 같은 가뭄대응을 위한 판단 기준이 없어 사전 대응이 곤란한 실정이다. 또한, 실제 가뭄 업무를 일선에서 처리하는 지자체 공무원 등이 지금까지 제시된 가뭄지수(SPI, PDSI 등) 및 확산 모델 등을 사전 대응에 활용하기에는 한계가 있는 것으로 나타났다. 이에 따라 본 연구에서는 장기유출모형(SWAT)의 매개변수 검·보정을 통해 장기간의 일단위 유출량을 추정하였으며, 감수곡선식을 도출하였다. 또한, 일단위 취수량과 감수곡선식의 관계분석을 통해 취수가능일수를 정량적으로 산정하였으며, 이를 용수공급 네트워크에 대입하여 읍면동 단위 적용 가능 범위를 제시하였다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권2호
• /
• pp.597-601
• /
• 2016

Background: Components of the systemic inflammatory response, combined to form inflammation-based prognostic scores (mGPS, NLR, PLR, PI, PNI) have been associated with overall survival. The aim of the present study was to compare various prognostic factors including many previously established parameters and such systemic inflammation-based prognostic scores in a series of incurable stage IV colorectal cancer (CRC) patients. Materials and Methods: Patients (n=167) with stage IV CRC undergoing surgical procedures between 2005 and 2013 were enrolled. Preoperatively (7-30 days before surgery), routine laboratory examinations were performed on the same day. We calculated scores using these data and analyzed the association with cancer specific survival (CSS) statistically. Results: Univariate analysis revealed significant associations between CSS and WBC, albumin, CRP, CEA values, mGPS, PNI, and PI values among preoperative factors. On multivariate analysis, high mGPS and high CEA independently predicted shorter CSS (p=0.001 and p=0.018). A new scoring system was constructed using mGPS and CEA. When patients were separated into three categorized using this system, the new score accurately predicted CSS (p < 0.001). Conclusions: The present study indicates that a new scoring system, consisting of mGPS and CEA, is a simple and useful tool in predicting the survival of patients with incurable stage IV CRC, and should be included in the routine assessment of these patients for decision making of appropriate treatment.