• 한국디지털건축인테리어학회논문집
• /
• 제12권4호
• /
• pp.117-124
• /
• 2012

The importance of the digital architecture is increasing more ever. Currently, CAD and 3D programs are used as design fields, but the BIM (building information modeling) is gradually interested. BIM is mandatory on the project more than 50 billion won ordered by the government since 2012, it will be expanded to a total of government orders by 2016. University needs to evaluate teaching methods and computer-aided design environments such as CAD and BIM. In this paper, we surveyed computer-aided design environments and teaching methods for 73 students at the J University of Department of architectural engineering. Main results are as follows: 1. Hardlock is uncomfortable but necessary program for the computer management. 2. The desk placement considering the behavior of the design students results in higher satisfaction. 3. Because a CAD subject was a difficult course content and progress is fast, students thought it is difficult to follow. Especially, first-year students answered it is difficult to learn program and understand the structure of the building at the same time. 4. First-year students want to learn CAD more. Second-, third-, fourth-year students want to learn Photoshop more. Supplement for these classes is required. 5. Students answered that a teaching method of a CAD subject would be good to their own practice after the professor demonstrates for students. The senior's assistance is also a high effective way in the class. 6. During class, students' activities such surfing the web and Kakao Talk on a smartphone disrupt the class, there is a need to regulate by a rule such as disconnect computers from a network and against using smartphone. Although the Internet with the popularization of smartphones confers a benefit on modern life, it causes damage to us. This is a hard part for a salaried workers as well as students studying equally. The self management is required and a professor needs to control and restraint in a university classroom. The professor's continuing interest to students can increase the effectiveness of learning.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제25회 추계학술대회논문집
• /
• pp.353-357
• /
• 2005

본 연구는 30톤급 엔진 개발에 필요한 실물형 가스 발생기를 개발하는 과정에서 분사기 LOx post에 발생한 손상에 대해 기술하였고 손상에 대한 원인 분석에 대해 논의하였다. 4분사기, 실물형 가스발생기 및 1차 재설계된 분사기에 대한 연소시험 결과를 기술하였고 이에 대한 원인으로 연소 불안정, 종단시 purge, LOx 분무의 낮은 모멘텀, 작은 recess number, 적은 LOx 분사기 유량, 큰 분무 각도 등이 주원인임을 알 수 있었다. 이 분석 결과에 따라 recess number를 증가, 분사기 LOx 및 연료 분무각 증가, LOx post 외벽과 연료막 사이 간격 축소, LOx post 벽 두께 증가의 방향으로 분사기에 대한 재설계가 이루어졌다.

• Animal cells and systems
• /
• 제9권2호
• /
• pp.79-85
• /
• 2005

Oxidized abasic residues arise as a major class of DNA damage by a variety of agents involving free radical attack and oxidation of deoxyribose sugar components. 2-deoxyribonolactone (dL) is a C1'-oxidized abasic lesion implicated in DNA strand scission, mutagenesis, and covalent DNA-protein cross-link (DPC). We show here that mammalian cell-free extract give rise to stable DPC formation that is specifically mediated by dL residue. When a duplex DNA containing dL at the site-specific position was incubated with cell-free extracts of Po ${\beta}-proficient$ and -deficient mouse embryonic fibroblast cells, the formation of major dL-mediated DPC was dependent on the presence of DNA polymerase (Pol) ${\beta}$. Formation of dL-specific DPC was also observed with histones and FEN1 nuclease, although the reactivity in forming dL-mediated DPC was significantly higher with Pol ${\beta}$ than with histones or FEN1. DNA repair assay with a defined DPC revealed that the dL lesion once cross-linked with Pol ${\beta}$ was resistant to nucleotide excision repair activity of cell-free extract. Analysis of nucleotide excision repair utilizing a model DNA substrate containing a (6-4) photoproduct suggested that excision process for DPC was inhibited because of DNA single-strand incision at 5' of the lesion. Consequently DPC mediated by dL lesion may not be readily repaired by DNA excision repair pathway but instead function as unusual DNA damage causing a prolonged DNA strand break and trapping of the major base excision repair enzyme.

• 한국구조물진단유지관리공학회 논문집
• /
• 제15권3호
• /
• pp.106-115
• /
• 2011

본 연구에서는 비선형 지진응답해석을 이용하여 유도된 전단 및 휨파괴형 부재가 혼합된 저층 철근콘크리트(RC) 건물의 비선형 요구내력스펙트럼을 수식화하여, 특정 연성률 별로 지진입력수준과 내진성능잔존률을 산정하여, 건물의 지진손상정도를 정량적으로 평가 가능한 새로운 내진성능 평가법을 제안하였다. 또한 저층 RC 건물을 대상으로 본 연구의 내진성능 평가법을 적용하여 평가한 결과와 보다 정밀한 부재수준의 비선형 동적해석을 실시하여 그 결과를 각각 비교 검토함과 동시에, 내진진단기준에서 입력지진동 0.2g 수준에 대해서 구조체에 대규모이상의 지진피해를 막기 위한 임계값으로 설정한 내진성능판정지표값 (Es=0.6)과의 상관관계를 분석하여 본 연구에서 제안한 내진성능 평가법의 타당성 및 그 적용가능성을 검증하였다. 본 평가법은 비선형해석 또는 능력스펙트럼법 등의 상세 내진성능 평가법을 수행하지 않고도 대상건물에 대한 연성률 단계별의 입력지진 수준, 지진손상도를 정량적으로 평가할 수 있다. 향후 전단 및 휨파괴형 부재가 혼합된 저층 RC 건물의 내진성능을 효과적으로 평가하기 위한 자료로서 활용이 가능하다고 판단된다.

• Childhood Kidney Diseases
• /
• 제24권2호
• /
• pp.107-114
• /
• 2020

Purpose: The purpose of this study was to evaluate the prevalence, clinical characteristics, and long-term clinical effects of hypertension in Korean childhood-onset systemic lupus erythematous (SLE) patients. Methods: The medical records of SLE patients, diagnosed by 2019 SLE European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria, who visited Samsung Medical Center from January 2009 to May 2019 were reviewed. Disease activity and long-term damage were evaluated using the Modified Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the Pediatric Systemic Lupus International Collaborating Clinics/ACR Damage Index (Ped-SDI), respectively. The sex-, age- and height-blood pressure standards recommended by the American Academy of Pediatrics 2017 guideline was used to define hypertension. Results: A total of 32 patients were enrolled in this study. The median follow-up duration was 7.3 years and females were predominant. The median ages at SLE and hypertension diagnoses were 14.2 and 14.3 years, respectively. The biopsy-proven lupus nephritis was detected in 90.6% and 37.5% were class IV. During the follow-up, 12 patients (37.5%) had hypertension. Among them, 2 patients had 3 episodes of posterior reversible encephalopathy syndrome and 5 patients had left ventricular hypertrophy (LVH). Univariate analysis showed baseline hypertension was significantly correlated with a lower estimated glomerular filtration rate, higher body mass index and SLEDAI at baseline. The development of hypertension during the follow-up was significantly correlated with obesity, LVH, and higher Ped-SDI. Conclusion: Our study revealed that hypertension in pediatric SLE is associated with obesity and renal function at SLE diagnosis and could affect long-term damage.

• Composites Research
• /
• 제22권1호
• /
• pp.22-31
• /
• 2009

최근 화석 연료가 고갈됨에 따라 대체 에너지 개발 연구가 활발히 진행되고 있다. 여러 대체 에너지들 중 풍력 발전기는 바람의 에너지를 전기적 에너지로 바꾸어 주는 시스템으로 매우 친환경적이기 때문에 다양하게 연구되고 있다. 따라서 본 연구의 목표는 500W급 소형 풍력 발전용 블레이드의 개발로서 외국에 비하여 상대적으로 풍속이 낮은 국내와 같은 지역에 적용할 수 있도록 설계 되어야 한다. 본 논문에서는 피로수명을 고려한 고효율 경량화 블레이드의 공력설계 및 구조설계 방법이 제안되었으며, 구조해석으로 선형 정적해석, 좌굴해석, 진동모드해석이 수행되었다. 또한 풍력 발전 시스템에 발생할 수 있는 유체충돌해석을 모사하였다. 해석결과들은 유압시험장비를 이용한 구조시험 빛 성능시험의 결과와 비교되었고, 비교적 잘 일치하여 설계결과의 안전성을 확인하였다.

• Journal of Periodontal and Implant Science
• /
• 제36권2호
• /
• pp.515-529
• /
• 2006

Periodontal regeneration refers to the restoration of bone, cementum and periodontal ligament to their original levels before damage from periodontal disease process. Various surgical techniques to the promotion of periodontal regeneration have been used. Bone graft and guided tissue regeneration have used for the regeneration of furcation involvements which caused by periodontal disease. Fibrin adhesive is agents that have been shown to be effective in periodontal regeneration and biological carrier. Calcium sulfate which is one of the resorbable barrier materials has used for guided tissue regeneration. The purpose of this study was to compare the clinical effects between bone graft using fibrin adhesive and calcium sulfate barrier in the mandibular class II furcation involvement. For the study, twenty-six class II furcation involved teeth were surgically treated. 13 furcation defects(test group) were treated with bonegraft and fibrin adhesive and the others(control group) were treated with bone graft and calcium sulfate barrier. Pocket depth, clinical attachment level and gingival recession were measured at baseline, postoperative 3 and 6 months. The results of the study are as follows: 1. The change of pocket depth and clinical attachment level in both groups was decreased significantly at 3, 6 months than at baseline(p<0.05). 2. The change of gingival recession in both groups was increased significantly at 3, 6 months than at baseline(p<0.05). 3. The change of pocket depth and clinical attachment level in both groups was decreased at 3, 6 months, and the change of gingival recession in both groups was increased at 3, 6 months but there were no statistically or clinically significant differences with both groups. 4. The significant reduction of the pocket depth and clinical attachment level exhibited marked changes at 3 months in both groups. In conclusion, the results of this study suggest that there are no statistically or clinically significant differences between fibrin adhesive and calcium sulfate barrier in the treatment of class II furcations using xenograft.

• 한국지진공학회논문집
• /
• 제22권3호
• /
• pp.175-184
• /
• 2018

In this paper, comparative analysis of the 9.12 Gyeongju and 11.15 Pohang earthquakes was conducted in order to provide probable explanations and reasons for the damage observed in the 11.15 Pohang earthquake from both earthquake and structural engineering perspectives. The damage potentials like Arias intensity, effective peak ground acceleration, etc observed in the 11.15 Pohang earthquake were generally weaker than those of the 9.12 Gyeongju earthquake. However, in contrast to the high-frequency dominant nature of the 9.12 Gyeongju earthquake records, the spectral power of PHA2 record observed in the soft soil site was highly concentrated around 2Hz. The base shear around 2 Hz frequency was as high as 40% building weight. This frequency band is very close to the fundamental frequency of the piloti-type buildings severely damaged in the northern part of Pohang. Unfortunately, in addition to inherent vertical irregularity, most of the damaged piloti-type buildings had plan irregularity as well and were non-seismic. All these contributed to the fatal damage. Inelastic dynamic analysis indicated that PHA2 record demands system ductility capacity of 3.5 for a structure with a fundamental period of 0.5 sec and yield base shear strength of 10% building weight. The system ductility level of 3.5 seems very difficult to be achievable in non-seismic brittle piloti-type buildings. The soil profile of the PHA2 site was inversely estimated based on deconvolution technique and trial-error procedure with utilizing available records measured at several rock sites during the 11.15 Pohang earthquake. The soil profile estimated was very typical of soil class D, implying significant soil amplification in the 11.15 Pohang earthquake. The 11.15 Pohang earthquake gave us the expensive lesson that near-collapse damage to irregular and brittle buildings is highly possible when soil is soft and epicenter is close, although the earthquake magnitude is just minor to moderate (M 5+).

• 대한토목학회논문집
• /
• 제43권5호
• /
• pp.543-553
• /
• 2023

이 연구는 국내 공용 중인 교량 형식 중 건설 빈도가 가장 높은 RC 슬래브 교량의 공용내하력을 간단하게 평가할 수 있는 방안에 관한 것이다. 다수의 RC 슬래브 교량이 오랜 공용기간으로 인해 상당한 노후화가 진행된 상태지만, 교량의 규모 상 1, 2종 시설물에 포함되지 않아 그동안 안전 관리에 소홀한 측면이 있다. 기존의 이론적 선행연구에서는 실측 처짐 및 실측 고유진동수에 의해 도출된 처짐응답비와 강성저하율의 관계를 이용한 RC 슬래브 교량의 손상도 평가 프로세스(안)이 제시된 바 있다. 이 연구에서는 손상도 평가 프로세스(안)의 적정성을 검토하기 위해 실 교량에 대한 평가 결과를 시설물 안전법의 안전등급 및 Matsui의 노후도 지수와 비교·검토하였다. 또한 손상도 평가 프로세스(안)의 현장적용성을 향상시켜 실측 고유진동수만으로 개략적인 공용내하력을 평가하는 개선된 방안을 제시하였다. 연구결과, 10% 정도의 공용내하력 평가 결과의 오차를 허용하는 경우, 이 연구에서 제시된 방법은 노후화된 RC 슬래브 교량의 안전성 평가 및 유지보수 우선순위 산정 등에 효율적으로 활용될 수 있을 것으로 판단되었다.

• 한국세라믹학회지
• /
• 제49권4호
• /
• pp.287-294
• /
• 2012

Ceramic Matrix Composites (CMCs) represent a class of non-brittle refractory materials for harsh and extreme environments in aerospace and other applications. The quasi-ductility of these structural materials depends on the quality of the interface between the matrix and the fiber surface. In this study, a manufacture route is described where in contrast to most other processes no additional fiber coating is used to adjust the fiber/matrix interfaces in order to obtain damage tolerance and fracture toughness. Adapted microstructures of uncoated carbon fiber preforms were developed to permit the rapid infiltration of molten alloys and the subsequent reaction with the carbon matrix. Furthermore, any direct reaction between the melt and fibers was minimized. Using pure silicon as the reactive melt, C/SiC composites were manufactured with an aim of employing the resulting composite for friction applications. This paper describes the formation of the microstructure inside the C/C preform and resulting C/C-SiC composite, in addition to the MAX phases.