Effect of Impact Load on Splice Length of Reinforcing Bars

Hyeon?Jong Hwang,Fan Yang,Li Zang,Jang?Woon Baek,Gao Ma 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.5

Impact loading damage of reinforced concrete (RC) members deteriorates bond strength of reinforcing bars. To understand the effect of strain rate on the bond strength of reinforcing bars in RC beams under impact load, drop hammer test was performed on twenty-four simply supported RC beams with lap spliced bars at the mid-span. The test parameters were reinforcing bar diameter, splice length, drop height, and hammer mass. The dynamic responses including the impact load history, mid-span deflection history, crack distribution, and strain history of reinforcing bar were evaluated. Although the designed bar development length was 31–69% of the requirement of current design codes under static load, the tensile strength of bar splices was greater than the dynamic yield strength when subjected to large impact energy under impact load. On the basis of the test results, existing design equations for the bar development length under static load were modified to consider the impact loading effect on the bond strength. Factors related to the strain rate effect of materials, impact damage, and impact energy loss were proposed. The prediction of the proposed method agreed well with the tensile strength of bar splices under impact load.

Overexpression of Zoysia ZjCIGR1 gene confers cold stress resistance to zoysiagrass

Yang‑Ji Kim,Dae‑Hwa Yang,Mi‑Young Park,Hyeon‑Jin Sun,Pill‑Soon Song,Hong‑Gyu Kang,Seok‑Cheol Suh,Yong‑Eok Lee,이효연 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.1

Zoysia japonica Steud. is a warm-season lawn grass popular in Korea and elsewhere. They are cultivated in many places such as river banks, roadside, and play grounds. However, there still is a disadvantage of frequent mowing, and the grass grows poorly under the chilly conditions. To develop a grass variety that circumvents these drawbacks, we cloned the chitininducible gibberellins-responsive1 gene (CIGR1) from zoysiagrass. The full length of the ZjCIGR1 (Zj; Zoysia japonica Steud.) gene was obtained by 5′/3′ RACE PCR and the phylogenetic tree showed that it belonged to the CIGR1-subgroup in the PAT1-group of GRAS protein family. Expression of the ZjCIGR1 in wild-type plants was confirmed in roots, meristems, leaves, and flowers, especially high in the flowers. The transgenic zoysiagrass was confirmed by PCR using gene-specific primers, phosphinothricin-acetyl-transferase (PAT) strip test, and Southern blot analysis. ZjCIGR1-overexpressing plants acquired tolerance to cold stress displaying morphological phenotypes characteristic of stress resistance. In addition, in the transformants, expression of the ZjCIGR1 as well as cold-regulated (COR) gene was increased compared to the wild-type plants under cold stress condition. These results suggest that ZjCIGR1 gene is an important candidate for regulating cold stress resistance.

암 환자의 우울과 통증 : 일 예비적 연구

양문정,전양환,한상익,한치화,엄현석 대한신경정신의학회 2000 신경정신의학 Vol.39 No.6

연구목적 : 암 환자에서 우울과 통증의 정도, 우울과 통증에 영향을 줄 수 있는 요인들을 조사하고, 우울과 통증사이에 어떤 연관이 있는지 알아보고자 하였다. 방 법 : 종양내과에 입원한 암 환자 25명(남자 : 10명, 여자 :15명)을 대상으로 하여 내과 병록지 거모, 환자 및 가족과의 면담을 시행하였다. 정신과적 진단은 DSM-IV진단 기준에 의하였으며, 우울의 정도는 Hamilton Rating Scale for Depression(HRSD)로 평가하였고 통증의 유무를 평가한 뒤, 통증이 있는 경우 Brief Pain Inventory(BPI)를 시행하여 통증의 강도(최대, 최소,평균,현재), 통증에 의한 기능 방해 정도, 진통제에 의한 호전정도를 점수로 평가하였다. 결 과 : 전체 환자중 주요 우울증이 32%(8명), 경도 우울증이 16%(4명), 적응장애가 16%(4명)이었다. HRSD점수는 통증의 최대강도, 평균강도, 현재강도, 통증에 의한 기능방해정도와 유의한 상관관계가 있었으나, 통증의 최소강도, 진통제에 의한 호전 정도와는 유의한 상관관계가 없었으며, 이환 기간과 HRSD점수 및 통증 점수 사이에도 유의한 상관관계가 없었다. 성별, 종교, 암의전이여부,병황의 인식 여부에 따라 HRSD점수와 통증 점수에 차이가 없었으나, 현재 미혼 또는 사별 상태에 있는 환자들에서 결혼하여 배우자가 있는 환자들보다 HRSD점수와 통증의 최소강도, 평균강도가 유의하게 높았다. 결 론 : 암환자에게서는 우울증과 통증이 있는 경우가 많았다. 우울증과 통증간에 밀접한 상관관계가 있음을 알수 있었다. 본 연구의 결과는 암 환자에서 우울증과 통증에 대한 보다 적극적인 평가와 개입이 이루어져야 함을 시사하는 것이다. Objective : This study was designed to evaluate how much depression and pain symptoms could be shown, what kink of factors affect them, and whether the correlation between them could be or not in patients with cancer. Methods : The subjects were composed of 25 patients with cancer who admitted a the department of oncology(male:10, female :15). We reviewed the medical record and interviewed patients and their family. A psychiatric diagnosis was made according to the criteria of the DSM-IV, and depressive symptoms were evaluated by Hamilton Rating Scale for Depression(HRSD). The intensity of pain(maximal, minimal, mean, present), disability due to pain, te effects of analgesics were measured by Brief Pain Inventory(BPI). Results : 32% of patients had major depressive disorders, 16% of patients had depressive disorders, NOS and 16% of the patients had adjustment disorders. The score of HRSD was significantly correlated wit the maximal intensity, mean intensity and present intensity of pain and disability due to pain, but not with minimal intensity and the effects of analgesics. Depression and pain were not correlated with duration of illness. Scores of depression and pain did not differ in sex, religion, metastasis, and the knowledge of illness. The widowed or unmarried patients showed significantly higher scores than patients living with the spouse in HRSD, minimal intensity and mean intensity of pain. Conclusion : In patients with cancer, depression and pain were highly prevalant. The relationship between depression and pain was shown in patients with cancer. These results suggest that more active evaluation and intervention of depression and pain should be carried out in patients with cancer.

충격하중을 받는 Al 박육부재의 에너지흡수 제어특성

양용준,황우채,서현경,김정호,심재기,양인영 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

In this study, concerns the crashworthiness of the widely used vehicle structure, square thin-walled tubes, which are excellent on the point of the energy absorbing capacity. An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by axial loading to develop the optimum structural members. The impact velocity was tested in the rage 4.698~8.2m/s. To efficiently review the collapse characteristics of these sections, the simulation have been carried out using explicit FEM package, LS-DYNA. The solutions compared with results the impact collapse experiment. Here, the controller are introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. To predict and control the energy absorption, we designed it in consideration to the it's influence, height, thickness, wide ratio in this study. When the controller used, the experimental results of crushing of square tubes controlled by the controller's elements showed a good candidate for a controllable energy absorption capability in impact axial crushing.

디젤엔진 발전기 세트의 저소음화에 관한 연구

주현돈,양승호 진주여자전문대학 2002 論文集 Vol.25 No.-

Diesel engine generator sets in heavy industry plants and residential/official buildings can cause serious noise problem. In this paper, a low noise diesel engine generator set is developed through constructing an acoustic enclosure with ventilation duct silencers that effectively block the acoustic flow but guarantee good thermal flow. Acoustic design of the enclosure which is initially layout by rule of thumb, is evolved systematically through numerical reanalysis procedure, based on indirect boundary element method(IBEM) with a commercial acoustic analysis code. The acoustic and cooling performances of the developed low noise diesel engine generator set are confirmed by the experiment.

UPFC를 이용한 전력계통의 융통전력 증대방안에 관한 연구

김재현,김양일,정성원,한양주 국립7개대학공동논문집간행위원회 2004 공업기술연구 Vol.4 No.-

Recently electrical industry has been rapidly restructured by deregulation in the developed countries. This paper focuses on the evaluation of UPFC control on available transfer capability(ATC) enhancement. Technical merit of UPFC technology on ATC boosting are analyzed. More effective control means for line flow and bus voltage are required for appling UPFC. The function of UPFC is to control the active and reactive powers and the voltage magnitude simultameously. This paper demonstrate enhancement of ATC by application of UPFC at IEEE 57-bus system.

Ni-Cr-Mo鋼의 熱處理에 따른 機械的 性質과 衝擊靭性에 關한 硏究

秋現植,梁權承,崔秉起 조선대학교 기초과학연구소 1987 自然科學硏究 Vol.10 No.1

The influence of heat treatment on the mechanical properties and the charpy impact toughness of Ni-Cr-Mo Steel in austenitizing temperature range between 750℃~1100℃ and tempering temperature range between 250℃~500℃ was studied. The results obtained from this study are summarized as follows; 1) The most impact energy is obtained at about 900℃ of austenitizing temperature, and at the temperature of more than 900℃, impact energy decreased. That was seen to be caused from coarse of martensite structure. 2) As the austenitizing temperature increased, strength and elongation decreased. As tempering temperature increased, strength and hardness decreased, but elongation increased. 3) When the tempering temperature was 350℃, the impact energy was lowest and as the temperature was high, the impact energy increased. 4) As the austenitizing time under constant austenitizing temperature was long, hardness and impact toughness decreased.

골결손과 치주질환 유도 후 성견 절치의 실험적 함입이동시 치주조직의 반응

황현식,박양수,최홍란 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.3

치주질환에 이환된 성인환자에서 상악전치의 치간공간과 아울러 정출이 발생된 경우 기능 및 심미의 회복을 위해서는 함입이동이 필요하다. 본 연구는 골하치주낭 즉, 수직적 골결손이 있는 절치의 함입이동시 치주조직 반응을 살펴보기 위하여 시행되었다. 상악 좌우 측절치에 골결손과 함께 치주질환을 유발시킨 성견 4마리를 실험대상으로 하여 양측 모두에 치주수술을 시행하고 결손부 최하방 치근면에 notch를 형성한 2주후 우측 제2측절치는 4주간 함입이동 후 4주간 보정을 시행한 실험측으로, 좌측 제2측절치는 구강위생관리만 시행한 대조측으로 사용한 바 조직소견을 통하여 다음과 같은 결론을 얻었다. 1. 함입이동없이 치주수술만 시행한 대조측의 조직소견은 치주낭 깊이의 감소를 보였으나 notch 부위부터 치주낭 기저부까지 긴 접합상피 상태를 보였으며 신생백악질이 형성된 일부에서만 결합조직 부착의 양상이 보였다. 2. 함입이동을 시행한 실험측은 대조측에 비하여 상피부착이 줄어든 반면 보다 넓은 신생 결합조직 부착 소견을 나타내었다. 3. 대조측과는 달리 실험측 notch 근처의 결합조직내에는 다수의 세포가 관찰되었으며, 신생 백악질 생성 역시 대조측 보다 많이 관찰되었다. 이상의 결과는 치주질환으로 인하여 정출된 치아에서도 철저한 염증조절과 구강위생이 유지되고 적절한 크기의 힘에 의하여 순수한 함입이동이 적용된다면 바람직한 치료결과가 가능함을 시사하였다. While periodontal disease results in the extrusion of upper incisors with interdental spacing in adult patient, the intrusive movement should be executed for the rehabilitation in terms of esthetics and function. The present study was performed to investigate the periodontal response following orthodontic intrusion of teeth with infrabony pocket. Bone defect and periodontal disease were produced adjacent to the both maxillary second lateral incisors in four adult dogs. Four weeks later, a flap operation was performed to eliminate inflammation and a reference notch was made on the root surface at the level of bottom of each defect. Two weeks after periodontal surgery, 4 weeks of intrusion and subsequent another 4 weeks of retention was executed on the right side of incisors while left incisors served as the control. Through the histologic analysis, following results were obtained. 1. Histologic section of control side showed the reduction of pocket depth after flap operation. However, the status of long junctional epithelium was observed while new connective tissue attachment occurred in a small area adjacent newly formed cementum. 2. Epithelial attachment was less around the intruded incisor while new connective tissue attachment was much more compared to the control side. 3. Plenty of cells were observed in the connective tissue around the reference notch of the intruded incisor and the degree of the new cementum formation was higher in the intruded incisor than the control. The results of the present study suggested that an orthodontic intrusion of periodontally involved and extruded incisors could be carried out with a desirable periodontal response, provided that inflammation is under control.

火災時 非常發電機 稼動에 관한 硏究

朱賢暾,梁承浩 진주여자전문대학 1996 論文集 Vol.19 No.-

Recently it has become particularly to be concerned with low noise emergency generator because generator sets caused noise affecting seriously people in buildings. In this study, I investigated the working of the low noise emergency generator at fire eruption, relation with fire equipment, and changing time from electric power to emergency power. I simultaneously estimated the changing time from electric power to emergency power at emergency.

경계요소법과 유한요소법에 의한 흡음판을 가진 구조물의 소음해석

주현돈,양승호 진주여자전문대학 2001 論文集 Vol.24 No.-

In many practical problems, the use of finite elements to discretize the fluid region leads to large stiffness and mass matrices. But, since the acoustic boundary element discretization requires to put elements only on the surface of structure, the size of matrices is reduced considerably. Here, we developed a numerical analysis program for the structural-acoustic coupling problems of the multi-region cavity, using boundary elements for the fluid regions and finite elements for the structure. By considering sound transmission through layered systems placed in a cavity, the accuracy of the coupled acoustical-structural finite element model has been verified by comparing its transmission loss predictions with analytical sloutions. Example problems are included to investigate the characteristics of the multi-region structural-acoustic coupling system with porous material.