• Computers and Concrete
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• 제21권5호
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• pp.547-557
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• 2018

This paper measures the mechanical response of precast pavement joints under moving axle loads using the finite-element method, and the models were validated with results of field tests. In order to increase the ability to use the non-linear FE analysis for design and assessment of precast pavement subjected to moving axle load, this paper investigated the effects of different load transfer between the slabs using the ABAQUS finite-element package to solve the nonlinear explicit model equations. The assembly of the panels using dowels and groove-tongue keys has been studied to assess the efficiency of keyway joint system. Concrete damage plasticity model was used to calculate the effects of permanent damages related to the failure mechanisms. With aggregate interlock as the only load transferring system, Load transfer efficiency (LTE) is not acceptable when the axle load reaches to slab joints. The Finite-element modelling (FEM) results showed that keyway joints significantly reduced tensile stresses developed at the mid-slab. Increasing the thickness of the tongue the LTE was improved but with increasing the height of the tongue the LTE was decreased. Stresses are transferred to the adjacent slab efficiently when dowels are embedded within the model. When the axle load approaches joints, tensile damage occurs sooner than compressive damage, but the damage rate remains constant, then compressive damage increases significantly and become the major form of distress under the dowels.

• 터널과지하공간
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• 제5권2호
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• pp.104-113
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• 1995

Shear strength of the discontinuity on which the pre-failure of rock slope was occurred during surface excavation was measured through the direct shear test using core samples obtained in-situ. Internal friction angle was increased as the roughness of discontinuity surface(JRC) was increased. Results of the tilt test using core samples of higher JRC also showed very similar trend as those of the direct shear test. When the samples replicated from natural cores were used int he tilt test, results of friction angles showed almost perfect continuation of the residual friction angles from the direct shear test. However, when the gouge material existed in the discontinuity the internal friction angle strongly depended upon the rate of filling thickness to the height of asperity irrespective of the JRC. Based on the results of both direct shear test and tilt test internal friction angle and cohesion of discontinuity, which reflect the in-situ conditions fo pre-sliding failure and also can be used for the optimum design of support system, were assessed. Two kinds of support measures which were expected to increase the stability of rock slope were considered; lowering of slope face angle and installation of rock cable. But, it was found that the first method might lead to more unstable conditions of rock slope when the cohesion of discontinuity plane was negligibly low and in that case the support systems of any kind which could exert actual resisting force were needed to ensure the permanent stability of rock slope.

• ETRI Journal
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• 제37권6호
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• pp.1154-1164
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• 2015

This paper proposes a fully sensorless driver for a permanent magnet synchronous motor (PMSM) integrated with a digital motor controller and an analog pre-driver, including sensing circuits and estimators. In the motor controller, a position estimator estimates the back electromotive force and rotor position using a sliding-mode observer. In the pre-driver, drivers for the power devices are designed with a level shifter and isolation technique. In addition, a current sensing circuit measures a three-phase current. All of these circuits are integrated in a single chip such that the driver achieves control of the speed with high accuracy. Using an IC fabricated using a $0.18{\mu}m$ BCDMOS process, the performance was verified experimentally. The driver showed stable operation in spite of the variation in speed and load, a similar efficiency near 1% compared to a commercial driver, a low speed error of about 0.1%, and therefore good performance for the PMSM drive.

• Steel and Composite Structures
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• 제46권5호
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• pp.621-635
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• 2023

The combination of replaceable and repairable properties in structures has introduced new approach called "Low Damage Design Structures". These structural systems are designed in such a way that through self-centering, primary members and specific connections neither suffer damage nor experience permanent deformations after being exposed to severe earthquakes. The purpose of this study is the seismic assessment of steel moment resisting frames with the aid of rigid rocking cores. To this end, three steel moment resisting frames of 4-, 8-, and 12-story buildings with and without rocking cores were developed. The nonlinear static analysis and incremental dynamic analysis were performed by considering the effects of the vertical and horizontal components of 16 strong ground motions, including far-fault and near-fault arrays. The results reveal that rocking systems benefit from better seismic performance and energy dissipation compared to moment resisting frames and thus structures experience a lower level of damage under higher intensity measures. The analyses show that the interstory drift in structures equipped with stiff rocking cores is more uniform in static and dynamic analyses. A uniform interstory drift distribution leads to a uniform distribution of the bending moment and a reduction in the structure's total weight and future maintenance costs.

• 대한의용생체공학회:의공학회지
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• 제44권4호
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• pp.264-274
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• 2023

Purpose: The objective is to extract insights that can contribute to the formulation of harmonized international policies and support measures for innovative medical devices and management systems. This study aims to propose effective strategies for future medical device innovation and healthcare delivery. Results: It investigates technological advancements, regulatory approval systems, insurance policies, and successful commercialization cases in South Korea, the United States, and the European Union. In 2018, the FDA implemented insurance coverage for Software as a Medical Device (SaMD) and recognized insurance coverage for Digital Therapeutics (DTx). Germany is a country that ensures permanent reimbursement for healthcare applications since 2020, making it the first country to provide legal health insurance coverage for fostering a digital ecosystem. Conclusion: The findings of this research highlight the importance of cultivating a supportive regulatory and environmental framework to facilitate the adoption of innovative medical devices. Continuous support for research and development (R&D) efforts by companies, along with the validation of clinical effectiveness, is crucial.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.188-189
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• 2020

In the field of architecture, concrete and steel bars are the most common and popular combinations. The relationship between the two in a structure is a complementary good that increases in utility when consuming both materials at the same time. However, the combination of the two, which has been perceived as semi-permanent, often faces repairs or reconstruction without its lifespan reaching decades. There are a number of deterioration factors at work for the reason for this phenomenon. Among them, the neutralization of concrete in particular refers to the process in which calcium hydroxide inside concrete reacts with carbon dioxide and loses alkalinity, which creates a corrosive environment for rebars inside concrete, causing serious damage to concrete. In this study, we intend to use a multi-physical analysis program using finite element analysis method to analyze the degree of carbonation according to the internal temperature and concentration of carbon dioxide in concrete, thereby contributing to the prediction of long-term neutralization of concrete and the research related to measures for neutralization of concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.167-168
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• 2022

Recently, starting with the permanent suspension of Gori 1 in Korea, the importance of the disposal of concrete structures in nuclear power plants has emerged, and environmental and safety are required to be proved accordingly. Safe radioactive waste disposal technology that immobilizes harmful radioactive elements, which are by-products of nuclear power, inside a solid matrix and recycling measures are needed to secure an efficient waste disposal space. This study was conducted to confirm whether recycled cement generated in the process of radioactive concrete treatment can be used as a solidifying material for radioactive waste treatment. In order to simulate the concrete exposed to radiation, aqueous solutions of Di-water, CsCl 1M, and CoCl₂ 1M were used as blending water at W/B 0.5. Tricalcium phosphate and Prussian blue were substituted with 5 wt.% based on the weight of recycled cement as a binder to improve solidification performance, and their hydration characteristic was analyzed.

• 대한안전경영과학회지
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• 제25권4호
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• pp.105-115
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• 2023

The purpose of this study is to identify psychological anxiety factors related to firefighters' field activities and suggest improvement measures. To investigate the actual status of psychological anxiety factors, a survey was conducted on approximately 3,500 current firefighters, and the responses of 505 people who participated in the survey were analyzed. As a research method, frequency analysis and cross-analysis were conducted according to the general characteristics of the participants to determine the actual level of psychological anxiety in each work field and the results were analyzed. As a result of the analysis, it was statistically confirmed that firefighters feel a lot of psychological burden due to legal and institutional inadequacies during dispatch, return, or field activities, and frequent friction with civil servants is also a major cause of psychological anxiety. Therefore, based on the results of this study, it is proposed to establish a permanent legal support team in each city and province, designate and operate a hospital dedicated to psychological treatment, and establish a special provision for traffic accidents during the return of fire trucks so that firefighters can concentrate on their duties without psychological anxiety. do.

• 한국치위생학회지
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• 제23권6호
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• pp.485-492
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• 2023

Objectives: The purpose of this study is to identify factors related to unmet dental care needs among Korean youth, enhance the utilization of dental services by adolescents, furnish basic data for youth-oriented dental projects, and improve access to medical care. Methods: The analysis utilized combined data from the basic and oral databases from the 6th (2013-2015), 7th (2016-2018), and 1st year of the 8th (2019) National Health and Nutrition Examination Survey. Results: The factors influencing unmet dental care needs were gender, age, household income level, and health insurance. Statistically significant results were observed in relation to the type of dental clinic, recent visits to a dental hospital, experiences of toothache within the past year, subjective oral health status, occurrences of permanent dental caries, and engagement in orthodontic treatment. Conclusions: When formulating future national policies and projects, it is imperative to consider the factors and underlying reasons for the unmet dental care needs of adolescents. It is also necessary to establish oral health policies and institutional measures tailored to the dental care of adolescents.

• 기록학연구
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• 제22호
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• pp.77-114
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• 2009

알권리(right to know)는 법 제도를 만들거나 개선하는 것만으로는 충족될 수 없다. 알권리는 제도보다 문화의 문제이기 때문이다. 그럼에도 불구하고 지속적인 제도개선요구가 필요하다. 알권리와 관련해서는 여러 법령이 있을 것이다. 특히 정보공개법, 공공기록관리법, 대통령기록관리법 등이 핵심이라고 할 수 있다. 공공기록관리와 대통령기록관리와 관련한 제도가 알권리가 깊은 관련이 있다는 것은 2004년 이후 기록관리혁신을 추진하면서 공유되었고, 그 결과 '국가기록관리혁신로드맵'이 채택되었다. 또, 2007년 '참여정부'의 '취재지원시스템선진화방안' 발표 이후 정부와 언론단체 등이 참여하여 구성한 '정보공개제도개선T/F'의 다수 의견이 반영된 정보공개법 개정안에는 그동안 제기된 문제들에 대한 제도 개선안을 마련하였다. 이런 개선방안이 제도를 개선하는 데에는 이르지 못하였다. 이 글에서는 그동안 제기되었으나 논의에 반영되지 않은 것들을 중심으로 몇 가지 제도 개선 사항을 제안하였다. 정보 비공개의 개념을 공개유예의 개념으로 전환, 정보공개기준을 구체적으로 비치하고 공개, 비공개대상 개인정보의 구체화, 내부검토를 이유로 비공개하는 정보의 구체화와 엄밀한 적용, 사유없는 속기록의 비공개 조항삭제, 비공개 상한 기한 설정 등이 그것이다. 그동안의 제도 개선 추진의 가장 큰 성과는 알권리가 정보공개제도에 한정하는 것이 아니고 기록관리라는 '원인'이 체계적 과학적이어야 한다는 것을 인식하게 된 것이다. 이것은 알권리가 내부고발과 같은 우연적 요소가 아닌 기록의 생산, 유통, 보존, 활용의 체계화라는 필연적 요소로 확보됨을 공유하게 되었다는 것이다. 기록정보의 공개와 관련해서는 더 많은 연구가 필요하다. 특히 국가기록원 등 영구기록관리기관에서의 기록 열람 문제, 그 과정에서 발생하는 저작권 문제 등 여전히 해결해야 할 난제들에 대해 학계와 해당 기관의 지속적인 연구가 필요하다.