• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.4
• /
• pp.73-80
• /
• 2022

This study evaluated changes in fluidity and rheological properties over time for 3D printed composite materials, and evaluated compressive strength and splitting tensile strength properties for laminated and molded specimens. The composite material for 3D printing starts to change rapidly after 30 minutes of extrusion, and the viscosity of the material tends to be maintained up to 90 minutes, but it was confirmed that construction within 60 minutes after mixing is effective. The compressive strength of the laminated test specimen showed equivalent or better performance at all ages compared to the molded test specimen. In the stress-strain curve of the laminated specimen, the initial slope was similar to that of the molded specimen, but the descending slope was on average 1.9 times higher than that of the molded specimen, indicating relatively brittle behavior. The splitting tensile strength of the P-V laminated specimen was about 6% lower than that of the molded specimen. It is judged that this is because the interfacial adhesion force against the vertical load is affected by the pattern direction of the laminated test specimen.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.127-134
• /
• 2021

When constructing a tunnel on a stable ground, stress is changed in the ground during excavation stage and installation of ground support materials. In the standards for safety evaluation of structures in use, it is suggested to perform numerical analysis reflecting the excavation stage. But method of seismic performance evaluation was not presented. Therefore, in this study, numerical analysis was performed with different analysis methods, and the results were compared and analyzed. As a result of the numerical analysis, seismic wave applied in the horizontal direction were no difference depending on the analysis methods. However, there was a big difference in the result according to the evaluation methods of tunnel member forces. When reviewing with the strength design method, the structure performance could be not satisfied depending on the existence or nonexistence of reinforcing bars. Based on these research results, it is suggested that the interpretation method should be clearly presented and reflected in the relevant standards.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.5
• /
• pp.219-227
• /
• 2024

The rapidly changing security environment and technological innovations of the 21st century present new challenges to military organizations. Particularly, as the MZ generation, comprised of Millennials (born 1981-1996) and Generation Z (born 1997-2012), emerges as the primary workforce in the military, traditional military personnel management methods are being called into question. The MZ generation, as digital natives, are technologically proficient, prioritize personal growth and quality of life, and prefer horizontal communication and participation. The purpose of this study is to reestablish talent acquisition and retention strategies for military organizations, considering the characteristics and demands of the MZ generation. To this end, we analyzed advanced talent management techniques from the corporate sector and explored ways to apply them to the unique context of military organizations. Additionally, by examining the current status and challenges of the Korean military, we attempted a balanced approach that considers both global trends and Korea's specific circumstances. The research results suggest various strategies including career development programs, cultural innovation, improvement of reward systems, participatory decision-making, enhancement of digital competencies, and creation of flexible work environments. These strategies are expected to improve the efficiency and competitiveness of military organizations while simultaneously enhancing job satisfaction and organizational commitment among MZ generation service members.

• The korean journal of orthodontics
• /
• v.33 no.2 s.97
• /
• pp.73-84
• /
• 2003

This study was performed to find out how much projection errors in the cephalometric measurements were made by vertical head rotation in taking posteroanterior cephalograms. 25 adults without any apparent facial asymmetry or severe sagittal skeletal discrepancy were selected and the posteroanterior cephalograms were taken with the head rotated $5^{\circ},\;10^{\circ}$ superior and inferior each to the reference $position(0^{\circ})$. The 7 height, 5 width and 6 angular measurements were taken at each 5 positions. Through the statistical analysis of all measurements taken at each rotated position, folowing results were obtained.1. The projection errors of height measurements were remarkably target than those of width or angular measure nents. f. Among the height measurements, the farther to the rotation axis the measurements were, the larger the projection errors were. 3. Among the width measurements, mandibular width and mandibular width of mandibular first molars showed significant differences between the values taken at each rotated position, while nasal width, maxillary width and intermolar width of maxillary first molars did not. 4. Among the angular measurements, the angle between horizontal reference line and the line that is connected to crista galli and antegonion or maxillare showed significant differences between the values taken at each rotated Position. The above results suggest that it is needed to the effort to keep constant head position for taking the useful posteroanterior cephalogra, because projection errors are caused by vertical head rotation.

• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.1
• /
• pp.1-17
• /
• 1998

두개의 임플랜트로 지지되는 overdenture를 이용한 하악무치악환자의 치료법은 경제적이면서, 실용적인 치료로 인정을 받고 있다. 하지만 해부학적인 조건으로 임플랜트를 설측 혹은 후방에 식립해야 되는 경우에는 일반적인 bar설계는 bar가 구강저 상방을 지나게 되어 혀운동, 발음, 위생관리 등에 많은 문제점을 부여한다. 이에 대한 해결방법으로 전방부 치조제 상에 보철물의 회전을 허용하는 angular bar를 설계할 수 있다. 하지만 이 설계는 임플랜트에 불리한 moment를 유발한다. 그럼에도 불구하고 뛰어난 유지력과 지지능력, 경제적인 면 때문에 angular bar는 임상에서 많이 사용되고 있다. 이에 본 연구는 angular bar의 전방 cantilever양을 달리하여 임플랜트 및 주변조직에 미치는 영향을 삼차원 유한요소분석법을 통해서 알아보고자 하였다. 이공사이의 하악골을 단순화시킨 준하악골모형에 직경 3.75mm인 브로네마르크 임플랜트 2개를 길이가 13,15mm인 경우로 설정하여 제 1소구치 부위에 식립하였다. 두 임플랜트를 연결하는 bar는 전방부 cantilever양을 0-5mm, 1mm씩 하여 6가지 경우를 가정하고 제작하였다. 각각 bar 중앙부에 수직압 (90도) 35N, 경사압(120도) 70N, 수평압(0도) 10N을 가하였으며 이때 나타나는 응력 분산형태와 임플랜트의 골유착에 불리하게 작용하는 최대주응력(인장력)과 변위량을 살펴보았다. 연구결과 다음과 같은 결론을 얻었다. 1. Cantilever양이 증가할수록 주변피질골과 임플랜트로 응력이 집중되었으며 상부 보철물의 변위량도 커졌다. 2. Cantilever양에 대한 수평압의 영향은 크지 않았으며 임플랜트 길이가 긴 것이 변위량과 응력이 작았다. 3. 경사압에 대한 응력의 변화는 cantilever양의 증가에 따라 급격히 증가하는 양상을 띠었으며 임플랜트길이가 응력 및 변위의 양에 미치는 영향은 없었다. 4. 수직압에 대한 응력의 변화는 초기에는 완만한 증가를 보이다가 일정 시점 지난 후에는 증가율이 커지는 경향을 띠었다. 증가현상이 두드러지기 전에는 길이의 증가가 응력의 분산효과는 가져왔으나 이후에는 길이의 응력분산 효과는 없었다. 5. 응력분포양상은 cantilever양이 증가할수록 골조직을 통한 분산정도는 작아지고 특정부위의 피질골과 임플랜트, 상부보철물에 집중되는 경향을 보였다. 6. 임플랜트와 주변 골조직으로의 응력분산능력이 예후를 좌우한다는 점에서 angular bar는 적합치 못하며 부득이한 경우는 임플랜트 길이를 길게 하고 최대한 3mm이내로 cantilever양을 제한하는 것이 추천된다.

• Journal of the Korean Geosynthetics Society
• /
• v.11 no.3
• /
• pp.43-51
• /
• 2012

This paper describes the stability evaluation of reinforced earth wall using geosynthetic strip based on field test. The wall facing, which is applied in field, is able to present excellent scenery, and the reinforcement has improvement effect of pullout resistance based on rounded band anchor. The measurement is conducted according to construction elapsed time of structure for earth pressure, horizontal displacement of wall facing and reinforcement strain in field test. The evaluation results show that the measured earth pressure is less than theoretical earth pressure due to dispersion effect of earth pressure by geosynthetic strip. The horizontal displacement of wall facing is also satisfied a empirical criteria. The measured strain of reinforcement had nearly no effect on stability of the reinforced earth wall. Therefore, the geosynthetic strip with rounded band anchor can be applied in the reinforced earth wall, and the reinforced earth wall with geosynthetic strip can be commonly used in field because it has a structural stability.

• Journal of the Korean Society of Radiology
• /
• v.12 no.4
• /
• pp.525-532
• /
• 2018

This study is filmed by applying the axial angle variation of the X-ray tube instead of the patient's position change during the perimetric examination of the ribs. A Reference image with the rib oblique examination using a chest phantom and experimental images applied with a six-phase variation in the axial angle by increasing $5^{\circ}$ tube angle each from $5^{\circ}{\sim}30^{\circ}$ from the vertical incident direction of the chest phantom to the right horizontal axis were obtained. For the quantitative comparative evaluation of the images, SNR and CNR were calculated for regions of interest in the experimental images based on the reference image. Also, the left-right rib ratio in the reference image and the left-right rib ratio in the experimental images are measured and compared. As a result of the study, the experimental images with a tube angle of $25^{\circ}$ were best shown in the measurements of the SNR, CNR and left-right rib ratio compared to the reference image with a standard examination method. The modified rib examinations will consider useful, if it is difficult to maintain the patient's examination position.

• Korean Journal of Environmental Agriculture
• /
• v.32 no.2
• /
• pp.148-154
• /
• 2013

BACKGROUND: Genetically modified(GM) trigonal cactus(Hylocereus trigonus Saff.) contained a coat protein gene of cactus virus X (CVX), which conferred resistance to the virus, phosphinothricin acetyltransferase (bar) gene, which conferred herbicide resistance, and a cauliflower mosaic virus 35S promoter (CaMV 35S). This study was conducted to evaluate the possible impact of GM trigonal cactus cultivation on the soil microbial community. METHODS AND RESULTS: Microorganisms were isolated from the rhizosphere of GM and non-GM trigonal cactus cultivation soils. The total numbers of bacteria, and actinomycete in the rhizosphere soils cultivated GM and non-GM trigonal cactus were similar to each other, and there was no significant difference. Dominant bacterial phyla in the rhizosphere soils cultivated with GM and non-GM trigonal cactus were Proteobacteria, Uncultured archaeon, and Uncultured bacterium. The denaturing gradient gel electrophoresis (DGGE) profiles show a similar patterns, significant difference was not observed in each other. DNA was isolated from soil cultivated GM and non-GM trigonal cactus, we analyzed the persistence of the inserted gene by PCR. Amplification of the inserted genes was not observed in the soil DNA, which was collected after harvest. CONCLUSION(S): This result suggests that the GM trigonal cactus cultivation does not change significantly the microbial community.

• Journal of Biomedical Engineering Research
• /
• v.20 no.4
• /
• pp.479-484
• /
• 1999

본 연구에서는 사람의 턱 운동과 턱 사이에 작용하는 힘(혹은 압력)을 그대로 나타낼 수 있는 저작로봇을 개발하는 것을 궁극적인 목표로 한다. 이러한 저작로봇이 개발되면, 치과의사가 환자의 턱운동에 나타나는 병변을 진단하고 치료하는데 큰 도움이 될 것으로 사료된다. 또한 , 본 연구에 채택한 병렬기구(parallel mechanism)에대한 순기구학적( forward kinematics)분석은 일반적인 병렬기구의 실계에도 응용될 것으로 기대된다. 본 연구진이 1차적으로 설계한 모델은 베이스와 플랫폼(platform), 그리고 이 둘을 연결하는 3개의 다리로 구성되어 있다. 다리와 플랫폼은 3자유도의 관절로 다리와 베이스는 1자유도의 경첩 관절로 연결되어 있으며, 이 3개의 경첩 관절은 베이스 위의 수평면에서 직선을 따라 움직인다. 경첩 관절의 수평 변위와 세 다리의 길이가 주어졌을 때 플랫폼의 위치와 오리엔테이션을 구하는 순기구학의 해( 解)를 계산해내는 알고리즘을 개발하였다. 이 알고리즘의 특징은 매 순간 오차를 계산하여 이 오차가 줄어드는 방향으로 나아가도록 시간간격(time step)을 조절하는 것이다. 본 알고리즘은 현재 가장 보편적으로 사용되고 있는 뉴튼-렙슨 방법에 비하여 3가지 장점을 나타내고 있다. 우선 , 초기치(initial guess)에 관계없이 수렴한다는 것이다. 또한, 본 알고리즘은 뉴튼-렙슨 방법에 비하여 수렴속도가 훨씬 빠르며, 연산 시간이 매우 짧아져 실제적인 실시간 적용에 적합하다. 마지막으로, 뉴튼-렙슨 방법에서는 여러 개의 해 가운데 어느 곳으로 수렴할 지 예측 할수 없으나 본 알고리즘에서는 초기치에 가장 가까운 해로 수렴한다. 이러한 순기구학의 다중성(multiplicity)문제를 해결하기 위하여 두 개의 조건을 제시하였으며, 이를 적용한 시뮬레이션 결과에 의하면 항상 원하는 해(true solution)에 수렴할 수 있었다.발생량의 감소를 기대 할 수 있는 친환경기술로 유지관리비를 최소화할 수 있는 장점이 있었다. 않은 사람들 중 미래의 검진실행의지에 건강소식지가 영향을 미친 경우는 48.7%였다. 보건교육을 받은 후 유방암 자가검진 실천율은 사업군에서 53.9%로 받기 전의 27.3%보다 증가하였으나 대조군의 경우는 별 차이가 없었다. 연령별로는 60대가 가장 높았고 사업군에서 검진율의 증가분은 30대가 가장 컸다. 교육수준별로는 사업군은 고졸이, 대조군은 전문대졸이 가장 높았고 사업군에서 검진율의 증가분은 고졸에서 가장 컸다. 보건교육 후 유방암과 관련된 건강지식의 정도는 사업군이 3.7점으로 대조군보다 유의하게 높았으며, 유방암 자가검진법을 실천하는 사람들의 동기는 ‘일반 대중매체의 영향’이 가장 많았으며 건강소식지가 동기인 경우도 20.4%였다. 사업군에서 건강소식지가 유방암 자가검진법 실천에 영향을 미친 경우가 79.6%였으며 유방암 자가검진법에 관한 보건교육을 받고 실천하지 않은 사람들 중 미래의 실천의지에 건강소식지가 영향을 미친 경우는 43.6%였다. 이상의 소견에서 지역주민을 대상으로 인쇄매체를 통한 보건교육은 인쇄물만으로도 쉽게 실천 할 수 있는 유방암 자가검진법이 가장 효과적이었으며, 자궁암검진에 관해서도 검진을 받을 수 있도록 지역사회의 보건의료의 하부구조를 정비하여 제도적 장치를 마련하고 정보를 제공한다면 자궁암검진 실천율도 증가할 것이다.고 12.9% 의 발달율을 보여 유의적인 차이를 보이지 않았다. 이상의 결과로 보아 핵이식 수정란을 효율적으로 생산하기 위하여 수핵난자의 세포질에 ionomycin 과 DMAP 의 혼합처리로 탈핵난자의 활성화를 유도하는 것이 효율을 증진시킬 수 있었다고 본다. 또한 공핵수정란을 수정 후 90시간과 114시간 개별 배양하여 할구를 공핵체로 핵이식에 이용하였을 때도 그룹배양에 비하여 효율이 떨어지지 않음을 알 수 있었으며, 수정란의 할구

• Journal of the Korean GEO-environmental Society
• /
• v.17 no.7
• /
• pp.15-25
• /
• 2016

In the present work, a number of advanced three-dimensional (3D) parametric finite element numerical analyses have been conducted to study the behaviour of single piles and pile groups in consolidating ground from coupled consolidation analyses. Single piles, $4{\times}4$ and $6{\times}6$ piles inside groups with a spacing of 2.5D were considered, where D is the pile diameter. It has been found that dragload and downdrag on the piles developed rather quickly at the early stage of consolidation. However, when the degree of consolidation was more than 50~75%, only little increases of dragload and downdrag were induced on the pile. Negative Skin Friction (NSF) on the pile in the fill layer was mobilised quickly and remained constant throughout further consolidation. The development of NSF is influenced both by the relative shear displacements at the pile-soil interface and the vertical effective soil stresses during consolidation. The former governed the early stage of consolidation and the latter affected the later stage of consolidation. The vertical effective soil stresses adjacent to the piles were reduced due to the shear stress transfer at the pile-soil interface, in particular for piles inside the pile groups. The range of NSF influence zone concerning the reductions of the effective vertical soil stresses was about 20D measured from the piles in the horizontal direction. On the contrary, the effective horizontal soil stresses acting on the piles were similar to those at the far field.