• 구강회복응용과학지
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• 제24권3호
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• pp.231-242
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• 2008

본 연구의 목적은 전부 도재관 시스템에서 코어-비니어 결합계면에서의 결합 강도를 평가하는데 있다. 본 연구에서 사용되어진 전부 도재관 시스템은 IPS Empress2 with IPS Eris, IPS e.max Press with IPS e.max Ceram과 IPS e.max ZirCAD with IPS e.max Ceram이다. 제조사의 지시에 따라 코어(N=36, N=12/system, 직경: 10mm, 두께: 3mm)를 제작하였고 초음파 세척을 시행하였다. 특별히 제작된 스테인리스 스틸 몰드를 이용하여 코어 상부에 비니어(직경: 3mm, 두께: 2mm)를 축성한 후 소성하였다. 소성 후, 초음파 세척을 시행하고 아크릴릭 레진에 매몰하였다. 제작된 시편은 $37^{\circ}C$의 증류수에 1주일간 보관하였다. 만능시험기(Z020, Zwick, Germany)로 시편의 전단결합강도를 측정하였고, 하중이 코어-비니어 계면에 가능한 가깝게 가해지도록 시편을 위치시키고, 파절이 일어날 때까지 1.00mm/min의 crosshead speed로 하중을 가하였다. 측정된 각 군의 평균전단결합강도($MPa{\pm}SD$)에 대한 통계적 유의성을 검증하기 위해 일원 분산분석을 시행하였으며, 사후검정은 Tukey test를 이용하였다(p=0.05). 또한 파절된 시편을 주사전자현미경(JSM-6360,JEOL, Japan)으로 파절양상을 관찰하였다. 파절양상은 코어 내에서의 응집성 파절, 비니어 내에서의 응집성 파절, 혼합형 파절 혹은 접착성 파절로 분류하였다. 코어와 비니어 계면에서의 평균전단결합강도($MPa{\pm}SD$)는 IPS-e.max Press가 $32.85{\pm}6.75MPa$, IPS Empress 2가 $29.30{\pm}6.51MPa$, IPS e.max ZirCAD가 $28.10{\pm}4.28MPa$로 나타났다. 통계적 분석 결과 각 시스템 간에서 유의한 차이가 없었다(P>0.05). 어떠한 시스템에서도 접착성 파절은 관찰되지 않았다. IPS Empress 2와 IPS e.max Press에서는 코어와 비니어 내에서의 응집성 파절이 관찰되었으며, IPS e.max ZirCAD에서는 혼합형 파절과 비니어 내에서의 응집성 파절이 관찰되었다.

• 구강회복응용과학지
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• 제23권1호
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• pp.55-68
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• 2007

The purpose of this study was to analyze the distribution of stress in the surrounding bone around implant placed in the first and second molar region. Two different three-dimensional finite element model were designed according to vertical bone level around fixture ($4.0mm{\times}11.5mm$) on the second molar region. A mandibular segment containing two implant-abutments and a two-unit bridge system was molded as a cancellous core surrounded by a 2mm cortical layer. The mesial and distal section planes of the model were not covered by cortical bone and were constrained in all directions at the nodes. Two vertical loads and oblique loads of 200 N were applied at the center of occlusal surface (load A) or at a position of 2mm apart buccally from the center (load B). Von-Mises stresses were analyzed in the supporting bone. The results were as follows; 1. With the vertical load at the center of occlusal surface, the stress pattern on the cortical and cancellous bones around the implant on model 1 and 2 was changed, while the stress pattern on the cancellous bone with oblique load was not. 2. With the vertical load at the center of occlusal surface, the maximum von-Mises stress appeared in the outer distal side of the cortical bone on Model 1 and 2, while the maximum von-Mises stress appeared in the distal and lingual distal side of the cortical bone with oblique load. 3. With the vertical load at a position of 2 mm apart buccally from the center, there was the distribution of stress on the upper portion of the implant-bone interface and the cortical bone except for the cancellous bone, while there was a distribution of stress on the cancellous bones at the apical and lingual sides around the fixture and on the cortical bone with oblique load. 4. With the changes of the supporting bone on the second molar area, the stress pattern on the upper part of the cortical bone between two implants was changed, while the stress pattern on the cancellous bone was not. The results of this study suggest that establishing the optimum occlusal contact considering the direction and position of the load from the standpoint of stress distribution of surrounding bone will be clinically useful.

• 한국산업정보학회논문지
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• 제23권1호
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• pp.13-21
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• 2018

AGVS (Automated Guided Vehicle System)는 작업 공간 내 특정 물건 또는 상품들을 자동으로 이동 시켜주는 물류 자동화의 핵심 기술이다. 기존의 AGV는 독립적인 실내위치인식 기술과 함께 각 AGV별로 주행경로 인식을 위해 레이저, 마그네틱, 관성 센서 등을 이용하기 때문에 고비용이며 유지 및 확장이 어렵다는 단점을 가지고 있다. 이러한 단점을 해결하기 위해 본 논문에서는 라인스캐카메라 기반의 마이크로 컨트롤러에서도 구현 가능한 경량화 된 패턴인식 기술을 이용하여 AGV의 주행제어뿐 아니라 위치인식을 동시에 할 수 있는 기술을 제안한다. 제안된 패턴인식기술은 각 AGV가 라인으로 표시된 경로를 인식하여 자율주행을 가능하게 할 뿐 아니라 경로 상에 바코드 형태의 간단한 이미지 형태로 설치된 패턴인식을 통해 AGV자신의 위치를 파악하는 기술을 동시에 제공하기 때문에 AGVS 구현 비용을 획기적으로 줄일 수 있을 뿐 아니라 경로 재설정 및 확장에 유리하다. 제안된 기술의 효용성 검증을 위해 마이크로 컨트롤러에서 동작 가능한 패턴인식기술을 구현하였고, AGV 프로토타입을 이용한 실험으로 그 결과 및 효용성을 검증하였다.

• 헤리티지:역사와 과학
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• 제55권4호
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• pp.138-164
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• 2022

서산 대죽리 패총은 해안선과 접하는 낮은 구릉의 경사지에 분포하며, 기반암은 유색광물이 많은 편암이 주류를 이루나 부분적으로 편마암상을 보인다. 유적은 양토질 표토와 식양질 심토로 구성되며 점토화도는 낮다. 패총 출토 빗살무늬토기의 산출상태는 거의 유사하나 여러 형태와 문양이 공존하며 색과 두께 및 기초물성은 조금씩 다르다. 이들은 태토구성, 비짐의 종류와 함량 및 흑심의 유무에 따라 세 유형으로 세분된다. IA형과 IB형은 각각 무흑심 및 유흑심 무색광물형이며, II형은 유흑심 유색광물형 토기이다. 모든 토기는 비가소성 유색광물을 포함하나, II형은 Mg과 Fe의 함량이 높은 흑운모, 녹니석, 활석, 투각섬석, 투휘석 및 각섬석을 다량 함유한다. 모든 토기는 유기물을 포함하며 광물입자의 입도와 분급 및 원마도가 불량한 것으로 보아, 유적 일대의 풍화토를 수급하여 특별한 수비과정 없이 태토로 사용하고, 특수한 용도를 위해 약간의 정선을 거친 비가소성 비짐을 첨가한 것으로 판단된다. 전체적으로 불완전 소성을 경험하였고, IB형은 산화도가 낮았으며 II형은 적색도와 산화 정도가 가장 높았던 것으로 판단된다. 이는 소성 온도와 비가소성 입자의 함량비에 따라 달라진 것으로, 광물 및 지구화학적 분석과 열이력 등을 종합하여 소성 조건을 해석하면 600~700℃의 범위를 보였다. 대죽리 패총의 빗살무늬토기는 조금씩 다른 산출상태와 광물조성을 가지며 물리적 성질도 약간 다르나, 근본적으로 같은 태토를 바탕으로 유사한 제작과정을 거친 것이다. 이는 대죽리 일대에 분포하는 기반암 및 풍화토의 조성과 거의 동일하다. 현재 대죽리에는 산업단지가 들어서 유적의 태토와 지질분포를 확인하기 어려우나, 신석기시대 토기의 제작에 필요한 재료는 주변에서 자급자족했을 개연성이 충분하다. 따라서 대죽리 패총을 남긴 집단은 유적 인근에 거주하며 패류 채집과 가공을 목적으로 유적을 방문하고, 패각과 함께 부서진 토기를 폐기한 것으로 해석된다.

• Journal of Welding and Joining
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• 제32권4호
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• pp.46-54
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• 2014

In this study, the effect of bonding temperature and bonding pressure on deformation and tensile properties of diffusion bonded joint of STS304 compact heat exchanger was investigated. The diffusion bonds were prepared at 700, 800 and $900^{\circ}C$ for 30, 60 and 90 min in pressure of 3, 5, and 7 MPa under high vacuum condition. The height deformation of joint decreased and the width deformation of joint increased with increasing bonding pressure at $900^{\circ}C$. The ratio of non-bonded layer and void observed in the joint decreased with increasing bonding temperature and bonding pressure. Three types of the fracture surface were observed after tensile test. The non-bonded layer was observed in diffusion bonded joint preformed at $700^{\circ}C$, the non-bonded layer and void were observed at $800^{\circ}C$. On the other hand, the ductile fracture occurred in diffusion bonded joint preformed at $900^{\circ}C$. Tensile load of joint bonded at $800^{\circ}C$ was proportional to length of bonded layer and tensile load of joint bonded at $900^{\circ}C$ was proportional to minimum width of pattern. The tensile strength of joint was same as base metal.

• Steel and Composite Structures
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• 제21권2호
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• pp.267-287
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• 2016

The seismic performance of the ordinary steel reinforced concrete (SRC) columns has no significant improvement compared to the reinforced concrete (RC) columns mainly because I, H or core cross-shaped steel cannot provide sufficient confinement for core concrete. Two improved SRC columns by constructing with new-type shaped steel were put forward on this background, and they were named as enlarging cross-shaped steel and diagonal cross-shaped steel for short. The seismic behavior and carrying capacity of new-type SRC columns have been researched theoretically and experimentally, while the shear behavior remains unclear when the new-type columns are joined onto SRC beams. This paper presents an experimental study to investigate the shear capacity of new-type SRC joints. For this purpose, four new-type and one ordinary SRC joints under low reversed cyclic loading were tested, and the failure patterns, load-displacement hysteretic curves, joint shear deformation and steel strain were also observed. The ultimate shear force of joint specimens was calculated according to the beam-end counterforce, and effects of steel shape, load angel and structural measures on shear capacity of joints were analyzed. The test results indicate that: (1) the new-type SRC joints display shear failure pattern and has higher shear capacity than the ordinary one; (2) the oblique specimens have good bearing capacity if designed reasonably; and (3) the two proposed construction measures have little effect on the shear capacity of SRC joints embedded with diagonal cross-shaped steel. Based on the mechanism observed from the test, the formulas for calculating ultimate shear capacity considering the main factors (steel web, stirrup and axial compression ratio) were derived, and the calculated results agreed well with the experimental and simulated data.

• 한국조경학회지
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• 제34권4호
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• pp.18-36
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• 2006

The purpose of this research was to establish a green-networks from the perfective of landscape ecology in order to improve the function of urban green spaces. The study site was Dalsu-Gu in Daegu City. This research consisted of three phases. In the first phase, field surveys were carried out in order to understand existing distribution pattern of green spaces in the study site. 533 green spaces surveyed in the first phase were classified into 7 patterns and 24 types. The total area of the green spaces in Dalsu-gu was 3,329ha. Specifically the area of the 'urban nature parks' type was 57.49% of the total area of green spaces in Dalsu-gu, and it was expected that 'urban nature parks' type can play important roles in the green-networks in Dalsu-gu. Two analysis with green spaces in 9 types including 'urban nature parks', 'rivers' and 'neighborhood parks' were performed to establish a basic network frame of the green-networks. In the second phase, 'mutual connectivity analysis' and 'mutual matrix analysis' were performed to select core green spaces of a green-networks using 'areas of each green space and a distance between each space' and 'a rate of green spaces and a rate of water permeable pavement'. The results of the second phase indicated that, in mutual connectivity analysis, large green spaces apart from each other were evaluated as having higher mutual connectivity than small green spaces near to each other. In mutual matrix analysis, the green spaces with higher mutual connectivity and the small green spaces near to each other were evaluated as having better mutual matrix. In the last phase, we structured a basic frame of the green-networks in Dalsu-Gu. The results suggested that the basic frame of the green-networks in Dalsu-Gu was composed on four green-network axes and its shape mirrored a cruciform(+) of northwest${\longleftrightarrow}$southeast directions and southwest${\longleftrightarrow}$northeast directions, The Duryu neighborhood park is at the central point of this green-networks.

• 대한기계학회논문집A
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• 제26권2호
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• pp.387-398
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• 2002

The impact response and damage of CLAS panel was investigated experimentally. The facesheet material used was RO4003 woven-glass hydrocarbon/ceramic and the core material was Nomex honeycomb with a cell size of 3.2mm and a density of 96 kg/㎥. The shield plane used was RO4003 and 2024-T3 aluminum. Static indentation and impact test was conducted to characterize the type and extent of the damage observed in two CLAS panels, and the performance of antenna used in a wireless LAN system. Correlation of peak contact force, residual indentation and the delamination area shows impact damage of the panel with an aluminum shield plane is larger than that of the panel with RO4003 shield plane, although the former is more penetration resistant. The damage was observed by naked eye, ultrasonic inspection and cross sectioning. The shape and size of delamination was estimated by ultrasonic inspection, and the area of delamination linearly increases as impact energy increases. The performance of impact damaged antenna was estimated by measuring return loss and radiation pattern. It was revealed that the performance of antenna was related to the impact damage and there was a threshold that the performance of antenna fell as impact energy level changed. The threshold was between the impact energies of 1.5J and 1.75J.

• 대한간호학회지
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• 제17권1호
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• pp.52-63
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• 1987

Il-primigravidas who visited antenatal clinic and their husbands were taught lamaze childbirth education by the investigator in the third trimester of pregnancy. Lamaze childbirth educational course consisted of six weekly class totaling twelve hours of instruction. A questionnaire was adminstered to subjects for the evaluation of Lamaze educational Program. 21-questions were rated on a Likert-type scale containing five responses and subjects described the advantages, the disadvantage, and the difficulties of lamaze childbirth education course. The results of the study were as follows; 1. The core contents of lamaze childbirth educational Program were Process of labor, anatomy and physiology of the female body, the care of newborn, maternal-infant attachment, breathing patterns to be used at the appropriate stage of labor, techniques for conscious relaxation of muscles during labor and delivery, and exercise to limber and prepare the body for the work of labor and delivery. All couples understood the above core contents very well and there were not significant differences between the understanding scores of wives and those of husbands (p>0.05). 2. 81.8% of couples Practiced breathing pattern to be used at the appropriate stages of labor one or three times a day and 72.7% of couples practiced conscious relaxation of muscles one or three times a day. 3. The contents of Lamaze childbirth educational program were easy for the couples to understand, and the total length, the amounts and the structures of 6-classes were appropriate. 4. Lamaze childbirth educational program was very useful, necessary, interesting, and successful to achieve the couples' objectives. 5. The couples expressed that they had positive attitude and high self-esteem, and reduced their anxiety on the pregnancy and labor.

• 인지과학
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• 제28권3호
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• pp.173-191
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• 2017

The theories of cultural evolution hold subtly or clearly different stances about definition of culture, pattern of cultural evolution, biases that affect cultural evolution, and relationship between culture and organism. However, the cultural evolution theories have a common problem to solve: As the evolutionary theory of life tries to explain the early steps and the origin of life, the cultural evolution theories also must explain the early steps of the cultural evolution and the role of the human capability that makes cultural evolution possible. Therefore, explanations of the human's unique traits including the cultural ability are related to determine which one is the most plausible among many cultural evolution theories. Theories that tried to explain human uniqueness commonly depict the coevolution of gene (organism) and culture. We will explicitly call the niche construction theory and the dual inheritance theory the 'gene-culture co-evolutionary theory'. In these theories, the most important concept is the 'concept of positive feedback'. In this paper, we distinguish between core positive feedback and marginal positive feedback, according to whether the trait that the concept of positive feedback explains is the trait of human uniqueness. Both types of positive feedback effectively explain the generality of human uniqueness and the diversity of human traits driven by cultural groups. However, this positive feedback requires an end, in contrast to negative feedback which can be continued in order to maintain homeostasis. We argue that the co-evolutionary process in the gene-culture co-evolutionary theories include only the positive feedback, not covering the cultural evolution after the positive feedback. This thesis strives to define the coevolution concept more comprehensively by suggesting the potential relationships between gene and culture after the positive feedback.