• 한국강구조학회 논문집
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• 제22권4호
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• pp.313-324
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• 2010

본 연구에서는 반강접 접합부 배치에 따른 구조물 거동특성을 파악하기 위하여 KBC2005 건축구조설계기준으로 비가새 5층 철골 구조물을 설계하여 모든 접합부를 완전 강접합부와 반강접 접합부로 이상화한 경우 그리고 반강접 접합부를 수직배치 및 수평배치한 경우에 대하여 비탄성 시간이력 구조해석을 실시하였다. 철골 보 및 기둥의 모멘트-곡률 관계는 화이버모델을 이용하여 확인하였으며 반강접 접합부의 모멘트-회전각 관계는 3-매개변수 파워모델 그리고 철골 보, 기둥 및 접합부의 이력거동은 3-매개변수 모델을 이용하여 나타내었다. 4개 지진파에 대한 재현주기 2400년 위험수준에 해당하는 최대지반가속도와 5% 층간변위에 대한 푸쉬오버 구조해석의 최대밑면전단력 발생 최대지반가속도에 대하여 시간이력 구조해석을 실시하여 밑면전단력, 지붕층 변위, 층간변위, 접합부 요구연성도, 기둥, 보 및 접합부의 최대휨모멘트 그리고 소성힌지 분포 등을 확인하였다. 반강접 접합부를 수직적으로 외부에 배치할수록 최대밑면전단력과 층간변위는 감소하며, 수평적으로 상부층에 배치할수록 접합부 요구연성도가 감소하였다. 푸쉬오버 구조해석과 시간이력 구조해석에서 최대층간변위 발생 위치가 다르고 크기는 푸쉬오버 구조해석에서 과대평가되었다. 밑면전단력, 층간변위 및 접합부 요구연성도를 위한 가장 바람직한 반강접 접합부 배치는 수직적으로 외부에 배치하는 것이다.

• 대한치과교정학회지
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• 제27권2호
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• pp.231-243
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• 1997

본 연구는 거대 편도를 가진 기능성 III급 부정 교합자의 구대 편도 절제술 전후의 인두강, 설골, 두부 위치의 변화 양상에 대해 알아보기 위해 단국 대학교 부속 치과 병원 교정과에 내원한 남녀 환자 42명을 대상으로 연구하여 다음과 같은 결론을 얻었다. 1. Enlarged tonsil을 보이는 기능성 3급 부정교합자는 1급 부정교합자보다 혀는 전방에 위치하고 설골은 하방에 위치한다. 2. Tonsillectomy 후에 편도 절제술전과 비교하여 혀는 후방에 위치하고, nasopharynx은 증가 양상을 보이며, 설골은상, 후방에 위치하며 counterclockwise rotation 양상을 보인다. 3. Tonsillectomy 후에 nasopharynx depth변화와 하악 전치 경사도, 혀의 수직적 변화와 cranial base에 대한 hyoid axis, hyoid의 수직적, 수평적 변화와 두경부 경사도, 두경부 경사도와 하악 전치간에 95% 유의수준으로 상관성을 보인다. 4. Tonsillectomy 후에 설골 장축의 counterclockwise rotation시 hya-NL의 감소와 nasopharyx의 증가를 보이고, 혀의 거상시 hya-NL의 감소를 보이며, 혀의 후방위치시 h-h1의 증가와 hya-ba-n의 감소를 보인다.

• 대한치과기공학회지
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• 제30권1호
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• pp.121-130
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• 2008

The purpose of this research project is to assess students' stress during clinical rotations and to suggest strategies for enhancing professional skills as well as the quality of clinical rotations among the students of dental technology. The participants included 200 sophomores and juniors from dental laboratory college located in Daegu and Jeju. Data was collected December 7, 2007, and March 7, 2008, by survey samplings. A total of 185 completed surveys were obtained and analyzed for this study. Findings from the study are summarized below. When age and stress were compared, it was found that younger students had higher levels of stress related to their environment, role, and activities. Regarding grade level and stress, students in lower levels were slightly (p<.01) more likely to have stress (Sophomore =2.91, junior =2.49). When the stress level was compared with students' satisfaction with their major, the less students were satisfied, the higher their level of stress was. The study found a slight (p<.05) difference between groups [satisfaction group (M=2.44), group in between satisfaction and dissatisfaction (M=2.58), and dissatisfaction (M=2.82)) in the relationship between satisfaction with the major and overall stress. Again, it appears that stress levels increase as satisfaction with the chosen major decreases. Third, the intensity of stress was affected by the environment in which students practiced, classmate relationships, roles, goals and values, and activities, and areas of performance. It showed that the groups unsatisfied and in-between with the quality of practice have more intensified stress than the group with satisfaction. The study showed a slight (p<.01) difference amongst groups [(satisfaction group (M=2.17), group in between satisfaction and dissatisfaction (M=2.68), and dissatisfaction (M=2.96)) in the relationship between satisfaction with the quality of the clinical rotation and overall stress. It appeared that higher levels of stress were seen with lower satisfaction with the major. Overall, students' level of stress was correlated with age and grade level, level of satisfaction in the major and the quality of the clinical rotation. Furthermore, schools need to focus on improving the environment where students practice, classmate relationships, roles, goals and values, and activities, and areas of performance. Dental laboratory colleges should concentrate on the basic case with the quality of clinical rotation and the chosen major. More skillful teaching and properly assigned clinical rotations and classes, along with a strong practical knowledge base applicable to clinical rotations will be needed in order to address these sources of dissatisfaction.

• Journal of Welding and Joining
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• 제29권6호
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• pp.56-64
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• 2011

Friction stir spot welding between 5454 aluminum alloy sheets with the different thicknesses of 1.4 and 1.0 mm was performed. In the welding process, the tool for welding was rotated ranging from 500 to 2500, and plunged to the depth of 1.8 mm under a constant tool plunge speed of 100 mm/min. And then, the rotating tool was maintained at the plunge depth during the dwell time ranging from 0 to 7 sec. The pull-out speed of the rotating tool was 100 mm/min. The increase of tool rotation speed resulted in the change of the macrostructure of friction-stir-spot-welded zone, especially the geometry of welding interface. The results of the tensile shear test showed that the total displacement and toughness of the welds were increased with the increase of the tool rotation speed, although the maximum tensile shear load was decreased. However, the change in the dwell time at the plunge depth of the tool did not produce the remarkable variation in the macrostructure and mechanical properties of the welds. In all cases, the average hardness in friction-stir-spot-welded zone was higher than that of the base metal zone. By the friction stir spot welding technique, the welds with the excellent mechanical properties than the mechanically-clinched joints could be obtained.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.106-109
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• 2006

Over the years, many researches have been performed to create 3D digital maps. Nevertheless, it is still time-consuming and involves a high cost because a large part of 3D digital mapping is conducted manually. To compensate this limitation, we propose methodologies to represent 3D objects as 3D symbols and locate these symbols into a base map automatically. First of all, we constructed the 3D symbol library to represent 3D objects as 3D symbols. In the 3D symbol library, the attribute and geometry information are stored, which defines factors related to the types of symbols and related to the shapes respectively. These factors were used to match 3D objects and 3D symbols. For automatic mapping of 3D symbols into a base map, we used predefined parameters such as the size, the height, the rotation angle and the center of gravity of 3D objects which are extracted from Light Detection and Ranging (LIDAR) data and 2D digital maps. Finally, the 3D map in urban area was constructed and the mapping results were tested using aerial photos as reference data. Through this research, we can identify that the developed the algorithms can be used as effective techniques for 3D digital cartographic techniques

• 대한구순구개열학회지
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• 제14권1_2호
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• pp.1-18
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• 2011

Skeletal malocclusion is the result of abnormal dimension and alignment of each skeletal component. Understanding on these mechanisms may help to elucidate the etiology of skeletal malocclusion and to establish population-oriented treatment plans. Attempts to subdivide the Angle's classification have been performed for Class III malocclusion, while few studies have been conducted for Class II malocclusion despite recent growing interests in Class II malocclusion. 200 adults (88 male, 112 female) with skeletal Class II malocclusion were collected and subdivided using cluster analysis, using the measurements representing the dimension and the alignment of each facial skeletal component. The properties of each cluster was grouped within the subjects and a comparison between the subjects and the control group (38 male, 35 female) with normal occlusion was performed. Six clusters were finally recognized in each male and female groups. The clusters in both genders were mainly characterized by the cranial base alignment, dimension of the posterior cranial base, dimension of the mandibular ramus and the degree of mandibular rotation. The results implicate that active treatment of mandible rather than the nasomaxillary complex may be primarily considered for the correction of Korean Class II skeletal pattern.

• 치과방사선
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• 제23권1호
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• pp.103-114
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• 1993

The purpose of this study was to determine whether any difference existed in craniofacial morphology between parents of children with cleft lip and/or palate and parents of children without cleft lip and/or palate as well as the characteristics of craniofacial morphology in parents of children with cleft lip and/or palate. Thirty three measurements of the various regions of cranium and face were obtained from lateral cephalometric radiograms in parents of 28 children with cleft lip and palate, 18 children with cleft lip, and 22 children with cleft palate. There were 28 couples and 40 single parents in this sample. There were 92 individuals including 41 males and 51 females. The measurements were compared with those in control subjects, including 40 adult males and 40 adult females, who had no history of craniofacial abnormalities. The total sample was compared for the sex independently. The obtained results were as follows. 1. In the cranium, both parents of cleft children had significantly shorter posterior cranial base length(S-Ba). 2. In the upper face, a significantly shorter anteroposterior length of maxilla(A'-Ptm'), particularly in the anterior region (A'-K), anterior facial depth(A-SBaL), posterior facia! height(Ptm'-SNL) and relation of subnasale to the cranial base (∠BaN'Sn) were noted in fathers of cleft children. But, all measurements were not found to be significantly different between experimental group and control group in all mothers. 3. In the lower face, both parents of cleft children showed a significantly greater Y axis angle(∠NSGn) and ramal plane angle(∠SNL-RP) in fathers of cleft children. Thus both patents showed a posteriorly rotation of mandible. The thickness of the lower lip(B-B') was significantly thicker in fathers of cleft children. 4. In the facial profile, a significantly shorter posterior facial height(S-Go) and greater angle of soft tissue facial convexity (∠BaN'Pog') were noted in the fathers of cleft children. But, all measurements were not found to be significantly different between experimental group and control group in all mothers.

• Journal of Welding and Joining
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• 제29권2호
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• pp.72-79
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• 2011

The scope of this investigation is to evaluate the effect of joining parameters on the microstructural features and mechanical properties of dissimilar aluminum alloys, 1mm-thickness fixing AA6K31 at the top position and fixing AA5J32 at the bottom position. The friction stir lap welds were studied under various welding conditions, rotation speed of 1000, 1250, 1500rpm and welding speed of 100, 300, 500, 700mm/min, respectively. Mechanical test has been investigated in terms of tensile shear test and hardness test. The results showed that three type nugget shapes such as onion ring, zigzag type, hooking with the void, have been observed with revolutionary pitch. All welding conditions fractured at the HAZ of top plate, A6K31 and also the strength compare with base metal of lap joints were low efficiency, 52~63%. The thickness of fractured position was decreased with the lower heat input conditions. The relationships were excellent due to linear between the effective thickness of fractured position and peak load. The fractured position was the interface between joint area and not joint area. Also the strength efficiency compared with base metal was lower than decreasing rate of thickness because the hardness was decreased at fractured position due to softened material.

• Journal of Yeungnam Medical Science
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• 제8권1호
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• pp.32-41
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• 1991

비호흡 장애 아동에서 인두편도의 절제가 치조안면골격에 미치는 영향을 연구하기 위해 비호흡 장애 아동 24명의 인두편도 절제전과 절제 1년후의 두부방사선 계측사진과 정상교합 아동의 1년전과 후의 두부방사선 계측사진을 비교분석함으로 다음과 같은 결과를 얻었다. 1. Cranial base variables 두 group간에 유의차가 나타나지 않았다. 2. Craniofacial variables 실험군에서 1년간 성장경향을 보면 Brachyfacial pattern으로 변했지만 대조군에서의 변화는 특정한 경향이 발견되지 않았다. 3. Maxillary variables 실험군에서 1년간 palatal plane의 경사가 평탄해졌고 그 외의 항목에서는 유의차가 발견되지 않았다. 4. Mandibular variables 두 group간에 1년간 성장량의 유의치는 mandibular plane angle과 gonial angle에서 나타났고 특히 실험군에서 감소가 일어났다. 5. Facial height variables 실험군에서 1년간 성장 변화가 하악골의 수평성장회전을 일으켰다. 전항목에서 통계적인 유의차를 나타냈다.

• Computers and Concrete
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• 제20권4호
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• pp.369-380
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• 2017

The effects of the vertical component of a ground motion on the earthquake performances of semi-ductile high-rise R/C structures were investigated in the present study. Linear and non-linear time-history analyses were conducted on an existing in-service R/C building for the loading scenarios including and excluding the vertical component of the ground motion. The ratio of the vertical peak acceleration to the horizontal peak acceleration (V/H) of the ground motion was adopted as the main parameter of the study. Three different near-source earthquake records with varying V/H ratio were used in the analyses. The linear time-history analyses indicated that the incorporation of the vertical component of a ground motion into analyses greatly influences the vertical deflections of a structure and the overturning moments at its base. The lateral deflections, the angles of rotation and the base shear forces were influenced to a lesser extent. Considering the key indicators of vertical deflection and overturning moments determined from the linear time-history analysis, the non-linear analyses revealed that the changes in the forces and deformations of the structure with the inclusion of the vertical ground motion are resisted by the shear-walls. The performances and damage states of the beams were not affected by the vertical ground motion. The vertical ground motion component of earthquakes is markedly concluded to be considered for design and damage estimation of the vertical load-bearing elements of the shear-walls and columns.