• Journal of Magnetics
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• 제18권3호
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• pp.348-351
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• 2013

Inconel 600 alloy, Ni base alloy, is widely used for steam generator tubings where sensitization occurs at grain boundaries and sensitization will induce tubing failures. This alloy has usually paramagnetic property, however, it transforms into ferromagnetic property along grain boundaries when sensitization occurs: this means NDE using magnetism for sensitization is possible. Therefore, in this study, Inconel 600 alloys were heat treated at 873 K from 0 to 400 hours so as to generate sensitization and their magnetic properties were investigated in detail. The saturation and the residual magnetization increase with increasing heat treatment time and take a maximum. On the other hand, the coercive force decreases with the increase in time of heat treatment. We confirmed that characteristics at only grain boundaries change into ferromagnetic phase by a MFM observation. As a trial for industrial application, heat treated Inconel 600 alloy was scanned by a magnetic field sensor, and the variations in magnetization were obtained nondestructively. The results indicate a feasibility of magnetic NDE for sensitization of Inconel 600 alloy.

• 한국공간구조학회논문집
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• 제20권4호
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• pp.177-184
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• 2020

This study evaluates safety assessment before and after repair of Seonamsa temple seungseon bridge, which refer to the representative Hongye bridge in Korea. In this approach natural frequency of the structure were considered in the modeling procedure. Trial & error method is applied to obtain the approximate natural frequency before and after retrofit construction. Stiffness of the actual structure was examined to account for the dynamic characteristics of Hongye bridge measured in the field and adjusting parameters in computer modeling. The safety and usability of the stone structure in terms of load bearing capacity and displacement were examined.

• 대한한방내과학회지
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• 제41권6호
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• pp.959-966
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• 2020

Objectives: To examine the fundamental characteristics of interventional clinical trials registered in the CRIS (Clinical Research Information Service) database. Methods: We systematically analyzed the status of Korean medical interventions using the search function of the CRIS database. Results: From 2010 to January 2020, 267 Korean medicine-related clinical trials were registered with CRIS. The studies, which included many randomized trials (80.14%), focused primarily on demonstrating the effectiveness and safety of acupuncture and Korean herbal remedies. Most of these studies were government-sponsored and researcher-led clinical trials, but a few were company-sponsored trials. All trials were small and need improvement. Conclusion: This study reviews the current status of clinical trials in the field of Korean medicine and the basic data that can be used to create evidence-based Korean medicine.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.565-578
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• 2022

Among Generation IV reactors, the sodium-cooled fast reactor (SFR) is attracting attention as a system having great potential for commercial use. Gas entrainment is a thermal-hydraulic issue related to the safety problem of the reactor core in the SFR. Typically, a dipped plate or baffles are installed under the free surface to suppress gas entrainment. However, these approaches can cause gas entrainment in other locations and require many trial-and-error and verifications. In this study, a new strategy using magnetohydrodynamics to suppress gas entrainment in the SFR is proposed. In a counter-flow model, a judgment criterion of gas entrainment occurrence was developed for both water and liquid metal. Moreover, the gas entrainment can be completely suppressed by applying a magnetic field.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.238-239
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• 2021

This study presented the development of a user centered school facility fire safety evaluation model that would support fire safety evaluation, which is globally recognized as being important in terms of school safety, to be more efficiently implemented in the school field mainly by students. The study consisted of five steps. First, actual condition survey tools were developed based on the major fire safety evaluation items derived through literature review. Second, the characteristics of domestic school facilities in terms of fire safety were developed using the survey tools. Third, an evaluation model at a level utilizable by students was developed based on the foregoing characteristics. Fourth, the applicability of the model was verified through a trial application of the model to elementary school students. Finally, legal and institutional improvement plans and fire safety education materials were presented through a policy proposal.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2020년도 추계학술대회
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• pp.151-152
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• 2020

운영 중인 터미널을 대상으로 운영 정책을 변경하기 위한 계획 및 실행 과정에서 현장 적용 결과 실패 가능성이 있어, 시행착오를 줄이기 위해 많은 시간과 노력이 요구된다. 터미널 운영 정책을 변경하기 위한 계획 단계에서 시뮬레이션 기술을 활용하여 의사결정을 지원할 수 있다. 본 연구는 시뮬레이션 기술 중 가상화 터미널 시스템을 활용한 사례를 제시한다.

• Geomechanics and Engineering
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• 제37권5호
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• pp.499-510
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• 2024

In northern China, abundant summer rainfall and a higher water table can weaken the soil due to salt heave, collapsibility, and increased moisture absorption, thus the chlorine saline soil (silty clay) needs to be stabilized prior to use in road embankments. To optimize chlorine saline soil stabilizing programs, unconfined compressive strength tests were conducted on soil treated with five different stabilizers before and after soaking, followed by field compaction test and unconfined compressive strength test on a trial road embankment. In situ testing were performed with the stabilized soils in an expressway embankment, and the results demonstrated that the stabilized soil with lime and SH agent (an organic stabilizer composed of modified polyvinyl alcohol and water) is suitable for road embankments. The appropriate addition ratio of stabilized soil is 10% lime and 0.9% SH agent. SH agent wrapped soil particles, filled soil pores, and generated a silk-like web to improve the moisture stability, strength, and stress-strain performance of stabilized soil.

• 한국과학교육학회지
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• 제9권1호
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• pp.53-67
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• 1989

General Physics CAI Program was developed for university science and engineering student. The program was restricted in the field of mechanics and was mainly aimed for individual tutorial. This project was supported by Government. Department of Education, physics attending their general physics classes in university. The program was written in BASIC and constructed by frame, 4 professors and 6 graduate students were involved in the project. Summary of this study is as follows. 1. The theory of CAI was illuminated from a new point of view to enhance usefullness of CAI. Also the structure of frame type CAI was studied. 2. The program was developed as follows 1) The program consisted of main program, pretest routine, tutorial routine, final test routine, and several other routines for program control. Whole program was written in BASIC. 2) 20 problems for pretest, 90 problems and subsequent hints and solutions for tutorial, 20 problems for final test were developed. 3) According to student's pretest result, tutorial course was routed through several different courses which contain different number of problems 4) The expected rate of achievment for final test was set to 75%. 5) Data of students response to problems including number of tries and time used were recorded for the purpose of achievment analisys 3. 22 students went through whole course and the results were as follows. 1) Pretest marks were widly distributed from 20 points to 100. It means that achievement of high school physics course were not enough. 2) Throughout tutorial course, students who had got higher mark in pretest answered correctly in the first trial at a higher rate of 78 %. Overall rate of correct answer in the second trial was distributed appropriatly. 3) Average mark of final test was 78.8 points, rather a higher rate of achievement than expected. This means that the program was constructed well.

• 융합신호처리학회논문지
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• 제12권4호
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• pp.322-332
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• 2011

본 논문에서는 한일공동VLBI상관기(Korea-Japan Joint VLBI Correlator, KJJVC)의 핵심 구성시스템인 VLBI상관서브 시스템(VLBI Correlation Subsystem, VCS) 본제품의 1차 성능시험에 대해 기술한다. VCS 본제품의 1차 성능시험의 주요 목적은 현장에 설치하기 전에 제작사에서 다양한 시험항목을 대상으로 시험을 수행하여 문제점을 확인 후 전체 시스템의 완성도를 높이는 것이다. 이번 성능시험에서는 VCS 시작품에서 발견된 FFT 재양자화의 유효비트 부족으로 인한 오버폴로어 문제점을 포함한 기능적인 시험을 수행하였다. 이번 VCS 본제품의 공장시험을 통하여 2008년 VCS 시작품의 성능시험에서 발견한 FFT 의 재양자화 문제점이 완전히 해결되었으며 VCS 본제품에 지연추적, 지연보상, 주파수 묶음 등의 중요 기능도 추가되었다. 그리고 실제 관측 데이터(광대역/협대역)를 이용한 상관처리 시험에서도 예측되는 상관결과가 출력되는 것을 확인하였다.

• Smart Structures and Systems
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• 제9권5호
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• pp.393-410
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• 2012

Conventional geotechnical instrumentation techniques available for monitoring of slopes, especially soil-nailed slopes have limitations such as electromagnetic interference, low accuracy, poor longterm reliability and difficulty in mounting a series of strain sensors on a soil nail bar with a small-diameter. This paper presents a slope monitoring system based on fibre Bragg grating (FBG) sensing technology. This monitoring system is designed to perform long-term monitoring of slope movements, strains along soil nails, and other slope reinforcement elements. All these FBG sensors are fabricated and calibrated in laboratory and a trial of this monitoring system has been successfully conducted on a roadside slope in Hong Kong. As part of the slope stability improvement works, soil nails and a toe support soldier-pile wall were constructed. During the slope works, more than 100 FBG sensors were installed on a soil nail, a soldier pile, and an in- place inclinometer. The paper presents the layout and arrangement of the instruments as well as the installation procedures adopted. Monitoring data have been collected since March 2008. This trial has demonstrated the great potential of the optical fibre monitoring system for long-term monitoring of slope performance. The advantages of the slope monitoring system and experience gained in the field implementation are also discussed in the paper.