• 콘크리트학회지
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• 제7권3호
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• pp.187-198
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• 1995

본 연구는 RC 박스거더교 상부구조의 체계신뢰성 해석과 체계신뢰성에 기초한 내하력 평가를 위하여 실용적이고 실제적인 신뢰성 모델 및 방법을 제안하였다. 시스템으로서 교량의 보유내하력을 정확히 예측한다는 것은, 특히 교량이 높은 여용성을 갖고 있고 열화손상이 심각한 경우에는 더욱 어려운 문제이다. 본 연구는 교량의 체계신뢰성에 상응하는 교량시스템강도로서 정의도리 수 잇는 등가의 시스템가동의 항으로 교량의 보유내하력을 평가하는 새로운 접근방법을 제안하였다. 즉, 이 방법은 체계신뢰성지수의 FOSM(Fdirst Order Second Moment)형태에서 유도된 등가시스템저항강도로서 보다 실제적이고 합리적인 극산시스템저항강도 평가방법이다. 본 연구에서 제안된 RC박스거더교를 위한 강도한계상태모형은 휨 및 전단강도에 기초하였다. 그리고 박스거더 상부구조의 체계신뢰성 문제는 주요 파괴 메카니즘이나 각거더의 한계파괴상태에 기초한 FMA(Failure Mode Approach) 로부터 획득한 직-병렬 혼합모델로서 정식화하였다. 제안된 모형의 신뢰성해석에는 AFOSM(Advanced First Order Second Moment) 과 IST(Importance Sampling Technique) 시뮬레이션 알고리즘을 사용하였다.

• 대한치과기공학회지
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• 제19권1호
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• pp.91-111
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• 1997

An aim of this study is to find out influenced factors of satisfaction degree on the clinical practice for the dental technology student and it can be provided the basic necessary data for the educational planning of the curriculum for the clinical practice. The target of study are selected form 7 junior health college students and colleges are located in around seoul form 14 junior health college throughout the nation. The questionnaries were distributed between 24th Feb to 30th July in 1997 to the 100 dental technicians who finished clinical practice and entered profession in 1997. All collected data were analysed by using SPSS/PC, Technical Statistic, One-Way ANOVA, Ttest, Person Correnlation Coefficient, Chrobach Alpha Coefficient and the result of the study is follow. 1) The satisfaction degree were classificated as 7 aspect and overall average score was 3.042. During that period satisfaction of personal relation aspect(M=3.737) shows highest level. Satsfiaction of clinical parctice(M=3.571) shows as second, Satisfiaction of environment(M=3.028), Satisfaction of guidance(M=2.915), satisfaction of subject are ordered of their scores. According to above study satisfaction's degree of subject show lowest level. 2) According to the result of verification of study. general character of student and satisfiaction degree has not much relation with sex, location of college, religion, period for enrolling college, teaching method of clinical practice. But the result show similar relation with following items. Satisfaction if subject and satisfaction of clinical practice(P=0.000), place of clinical practice and satisfaction of clinical practice(P=0.002), Academic record of college and satisfaction of clinical practice(P=0.000). 3) The relation of satisfaction(Subject, method of teaching, environment, period, rating, personal relation) of clinical practice and age of investigation's target Older student show higher satisfaction(P=0.040). Also method of teaching, environments, period, rating, personal relation has similarities with satisfaction. Therefore student who has higher satisfaction of clinical practice they also have higher rate for subject, environment, period, personal relation. 4) The result fo investigation, most interesting subject was crown & bridge and most difficult factor was too many simple-works to the student. One of ideal factor was discussing with counselor before they choose place for clinical practice. Third grade and first semester is most efficient time for clinical practice and 8 week is proper period for clinical practice. Clinical practice is absilutory mecessary and we find out most student rated positively. However we need more specific study about satisfcation of each subject. Because it shows lowest level and we need more pay attention for planning of clinical practice.

• 한국강구조학회 논문집
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• 제11권2호통권39호
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• pp.213-222
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• 1999

ALFD방법은 연속합성판형교의 과재하중과 최대하중에 대한 강도검토에 있어서 실제적인 거동을 나타낼 수 있는 탄소성해석법이다. 주어진 하중으로 인한 최대 정, 부모멘트단면에서의 항복은 활하중이 통과한 후에 잔류하는 소성회전을 일으킨다. 또한 제조시의 잔류응력으로 인하여 이론적인 항복모멘트 이하에서도 소성변형을 일으킨다. 이러한 국부항복은 다음에 작용되는 과재하중하에서 탄성화되어 정의 자생모멘트를 유발한다. 본 연구에서는 지점과 최대 정모멘트 단면에서의 단위소성회전각으로 인한 자생모멘트를 공액보법과 3연모멘트법에 의하여 구하였고, 9개의 설계경간을 지점단면을 감소시켜가면서 본 연구에서 개발한 전산프로그램에 의하여 연속관계와 모멘트-비탄성회전각 실험곡선과 일치하는 자생모멘트를 구하였다. 또한 한국도로교시방서에 준하여 비조밀단면을 갖는 3경간 연속합성판형교의 평가를 수행하였다.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.1-15
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• 2020

The aim of this paper is to simply present live load factor calculation methodology formulation with the addition of a simple new future load projection procedure to previously proposed two methods. For this purpose, Oregon Weigh-in-Motion (WIM) data were used to calculate live load factors by using WIM data. These factors were calculated with two different approaches and by presenting new simple modifications in these methods. A very simple future load projection method is presented in this paper. Using four different WIM sites with different average daily truck traffic (ADTT) volume, and all year data, live load factors were obtained. The live load factors, were proposed as a function of ADTT. ADTT values of these sites correspond to three different levels which are approximately ADTT= 5,000, ADTT = 1,500 and ADTT ≤ 500 cases. WIM data for a full year were used from each site in the calibration procedure. Load effects were projected into the future for the different span lengths considering five-year evaluation period and seventy-five-years design life. The live load factor for ADTT=5,000, AASHTO HS20 loading case and five-year evaluation period was obtained as 1.8. In the second approach, the methodology established in the Manual for Bridge Evaluation (MBE) was used to calibrate the live load factors. It was obtained that the calculated live load factors were smaller than those in the MBE specifications, and smaller than those used in the initial calibration which did not convert to the gross vehicle weight (GVW) into truck type 3S2 defined by AASHTO equivalents.

• 전력전자학회논문지
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• 제7권1호
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• pp.30-40
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• 2002

본 논문은 250w 메탈 할라이드 램프용 전자식 안정기의 개발에 관한 연구로써 안정기의 입력 역율은 PFC IC를 이용하여 개선하였고, 벅 Type의 DC-DC 컨버터를 회로에 삽입하여 인버터회로에서 램프의 정격전압만을 공급할 수 있도록 함으로써 인버터 스위칭소자의 스트레스를 줄이게 되었다. 인버터의 형태는 풀 브릿지로 하였고 램프 점등을 구형 저주파에 고주파 성분을 첨가하는 방식으로 음향공명현상을 제거하였다. 또한 LC 회로를 이용한 간단 한 점화기 회로를 개발하였다. 벅 컨버터의 출력 전압을 조절하여 램프의 전압이 가변되는 원리를 이용하여 조광 제어를 할 수 있으며 계절별 및 시간대별로 점등시간과 조도조절이 가능토록 하였다. 벅 컨버터 출력 전압의 조절과 무부하 보호 및 과전류 보호 기능은 마이크로프로세서의 프로그램을 개발하여 수행하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.240-263
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• 2021

One of the biggest challenges that the software industry is facing today is to create highly efficient applications without affecting the quality of healthcare system software. The demand for the provision of software with high quality protection has seen a rapid increase in the software business market. Moreover, it is worthless to offer extremely user-friendly software applications with no ideal security. Therefore a need to find optimal solutions and bridge the difference between accessibility and protection by offering accessible software services for defense has become an imminent prerequisite. Several research endeavours on usable security assessments have been performed to fill the gap between functionality and security. In this context, several Multi-Criteria Decision Making (MCDM) approaches have been implemented on different usability and security attributes so as to assess the usable-security of software systems. However, only a few specific studies are based on using the integrated approach of fuzzy Analytic Network Process (FANP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) technique for assessing the significant usable-security of hospital management software. Therefore, in this research study, the authors have employed an integrated methodology of fuzzy logic, ANP and TOPSIS to estimate the usable - security of Hospital Management System Software. For the intended objective, the study has taken into account 5 usable-security factors at first tier and 16 sub-factors at second tier with 6 hospital management system softwares as alternative solutions. To measure the weights of parameters and their relation with each other, Fuzzy ANP is implemented. Thereafter, Fuzzy TOPSIS methodology was employed and the rating of alternatives was calculated on the foundation of the proximity to the positive ideal solution.

• 한국수자원학회논문집
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• 제30권6호
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• pp.671-678
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• 1997

전자파를 이용한 하천수 표면 유속계를 하천 유량 측정에 사용하여 실용성과 문제점을 분석하였다. 표면 유속계의 평가는 선박 실험용 선형수조를 이용하여 수행하였다. 그 결고, 수직각을 20$^{\circ}$, 35$^{\circ}$, 45$^{\circ}$로 하였을 때 유속측정 평균값의 오차는 5.5% 이하였다. '95년 8월 26일 8~10시 사이에는, 남한강 여주대교 지점에서 홍수 유속을 측정하였다. 500m 길이의 교량에 대하여 23개 지점에서 측정한 결과, 표면 유속값은 약 2~4m/s였다. 수심평균 유속 환산계수를 0.85로 하고, 유량을 환산한 결과는 약 10,500 ㎥/s였다. 환산유량값은 수위-유량식이나 부정류 계산에 의한 값과 $\pm$2% 이내의 편차를 보였다. 자료 사용 간격을 40m 또는 60m로 변경하여 유량을 환산하여도 별다른 차이가 없었다. 평상시의 유량측정은 '96년 하반기에 대청교 지점에서 수행하였다. 대청댐의 방류량을 기지값으로 하여 수심평균 유속 환산계수를 추정한 결과 0.83~0.87의 범위에 있었다. 계기 자체의 미세오차와 바람의 영향은 계속 연구되어야 하지만, 하천의 홍수 유량측정에 표면유속계를 사용하는 것은 간편하고 실용적인 대안이 될 수 있음을 확인하였다.

• Journal of Korean Neurosurgical Society
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• 제60권2호
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• pp.225-231
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• 2017

Objective : Solid bone fusion is an essential process in spinal stabilization surgery. Recently, as several minimally invasive spinal surgeries have developed, a need of artificial bone substitutes such as demineralized bone matrix (DBM), has arisen. We investigated the in vivo bone growth rate of DBM as a bone void filler compared to a local autologous bone grafts. Methods : From April 2014 to August 2015, 20 patients with a one or two-level spinal stenosis were included. A posterior lumbar interbody fusion using two cages and pedicle screw fixation was performed for every patient, and each cage was packed with autologous local bone and DBM. Clinical outcomes were assessed using the Numeric Rating Scale (NRS) of leg pain and back pain and the Korean Oswestry Disability Index (K-ODI). Clinical outcome parameters and range of motion (ROM) of the operated level were collected preoperatively and at 3 months, 6 months, and 1 year postoperatively. Computed tomography was performed 1 year after fusion surgery and bone growth of the autologous bone grafts and DBM were analyzed by ImageJ software. Results : Eighteen patients completed 1 year of follow-up, including 10 men and 8 women, and the mean age was 56.4 (32-71). The operated level ranged from L3/4 to L5/S1. Eleven patients had single level and 7 patients had two-level repairs. The mean back pain NRS improved from 4.61 to 2.78 (p=0.003) and the leg pain NRS improved from 6.89 to 2.39 (p<0.001). The mean K-ODI score also improved from 27.33 to 13.83 (p<0.001). The ROM decreased below 2.0 degrees at the 3-month assessment, and remained less than 2 degrees through the 1 year postoperative assessment. Every local autologous bone graft and DBM packed cage showed bone bridge formation. On the quantitative analysis of bone growth, the autologous bone grafts showed significantly higher bone growth compared to DBM on both coronal and sagittal images (p<0.001 and p=0.028, respectively). Osteoporotic patients showed less bone growth on sagittal images. Conclusion : Though DBM alone can induce favorable bone bridging in lumbar interbody fusion, it is still inferior to autologous bone grafts. Therefore, DBM is recommended as a bone graft extender rather than bone void filler, particularly in patients with osteoporosis.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.496-500
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• 2010

Objective : Surgical treatment of lumbosacral foraminal stenosis requires an understanding of the anatomy of the lumbosacral area in individual patients. Unilateral facetectomy has been used to completely decompress entrapment of the L5 nerve root, followed in some patients by posterior lumbar interbody fusion (PLIF) with stand-alone cages Methods : We assessed 34 patients with lumbosacral foraminal stenosis who were treated with unilateral facetectomy and PLIF using stand-alone cages in our center from January 2004 to September 2007. All the patients underwent follow-up X-rays, including a dynamic view, at 3, 6, 12, 24 months, and computed tomography (CT) at 24 months postoperatively. Clinical outcomes were analyzed with the mean numeric rating scale (NRS), Oswestry Disability Index (ODI) and Odom's criteria. Radiological outcomes were assessed with change of disc height, defined as the average of anterior, middle, and posterior height in plain X-rays. In addition, lumbosacral fusion was also assessed with dynamic X-ray and CT. Results : Mean NRS score, which was 9.29 prior to surgery, was 1.5 at 18 months after surgery. The decrease in NRS was statistically significant. Excellent and good groups with regard to Odom's criteria were 31 cases (91%) and three cases (9%) were fair. Pre-operative mean ODI of 28.4 decreased to 14.2 at post-operative 24 months. In 30 patients, a bone bridge on CT scan was identified. The change in disc height was 8.11 mm, 10.02 mm and 9.63 mm preoperatively, immediate postoperatively and at 24 months after surgery, respectively. Conclusion : In the treatment of lumbosacral foraminal stenosis, unilateral facetectomy and interbody fusion using expandable stand-alone cages may be considered as one treatment option to maintain post-operative alignment and to obtain satisfactory clinical outcomes.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.61-71
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• 2010

기 수행된 1, 2종 교량에 관한 정밀안전진단 등의 많은 사례를 분석해 보면, 실제로 많은 경우 외관상태가 교량의 대표등급 결정에 지배적인 요인이 되는 것을 볼 수 있다. 본 연구는 기 시행된 점검 및 진단 자료를 학습사례집합으로 인공지능 분야의 귀납적 학습법을 활용하여 철근 콘크리트 교량 바닥판의 상태평가를 지배하는 상태속성들의 교량등급에 대한 계층적 영향도와 구조적 연관성을 분석하였다. 이는 세부적으로 목표속성은 평가등급으로, 평가속성은 1방향균열, 2방향균열, 백태, 박락 및 층분리, 재료분리 등 7가지로 구성하고, 엔트로피 분석을 통해 주요 속성의 정보량, 정보기대값 및 정보 이득을 산정하고 범주별 상태 등급 분포를 분석하였다. 이를 위해 본 논문은 먼저 6개 교량에 대한 안전진단보고서를 토대로 상태등급 평가 과정에서 각 속성이 미치는 간접적 영향을 개관하고 정보공학적 분석의 동기를 부여하였다. 아울러 본 연구는 정보 변별력에 대한 순서로 평가를 지배하는 주 속성 및 조건별 하위 속성 연관성을 의사결정트리 형태로 나타내어 계층적 영향 및 속성간의 구조적 연관성을 보임으로써 손상에 대한 이해도를 높이고 차후 상태평가를 위한 합리적 접근을 지원할 수 있도록 하였다.