• Journal of the military operations research society of Korea
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• v.35 no.2
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• pp.77-86
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• 2009

The encounter probability graph is measured by the chance(in percent) that a vehicle, blindly moving through a minefield, will detonate a mine. The encounter probability graph versus minefield density is presented in ROK and US Army field manual but this graph is baseless because these data had not been presented as those of live mobility or wargame. In this paper, we verified this graph building procedure model as using computer program. The result values of program are almost like those of graph. Therefore this model for our to suggest have validation, verification that a modeling demand and we convince that this model will be useful for calculating encounter probability of multiple vehicles.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.283-298
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• 2008

The purpose of this study was to evaluate mechanical fit of fixture- abutment-screw interface in the internal connection implant systems. In this study, each two randomly selected internal implant fixture- abutment assemblys from Certain, Xive, Replace, Ankylos, SS II. were used. The implants were perpendicularly mounted in liquid unsaturated polyester by use of dental surveyor. Each abutment was connected to the implant with recommended torque value using a torque controller. All samples were cross-sectioned with grinder-polisher unit after embeded in liquid unsaturated polyester, and then fixture-abutment-screw interfaces of all samples by using optical microscope and scanning electron microscope were analyzed. Conclusively, although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal fixture-abutment connections which provides intimate contact with the implant walls to resist micromovement, resulting in a strong stable interface.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.370-378
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• 2016

Purpose: The purpose of this study was to investigate screw joint stability and sagittal fit between internal connection implant fixtures of two different manufacturers and customized abutments. Materials and methods: Internal connection implant systems from two different manufacturers (Biomet 3i system, Astra Tech system) were selected for this study (n=24 for each implant system, total n=48). For 3i implant system, half of the implants were connected with Ti ready-made abutments and the other half implants were connected with Ti CAD-CAM custom ones of domestic-make (Myplant, Raphabio Co., Seoul, Korea) and were classified into Group 1 and Group 2 respectively. Astra implants were divided into Group 3 and Group 4 in the same way. Micro-CT sagittal imaging was performed for fit analysis of interfaces and preloading reverse torque values (RTV) were measured. Results: In the contact length of fixture-abutment interface, there were no significant differences not only between Group 1 and Group 2 but also between Group 3 and Group 4 (Mann-Whitney test, P>.05). However, Group 2 and Group 4 showed higher contact length significantly than Group 1 and Group 3 in abutment-screw interface as well as fixture-screw one (Mann-Whitney test, P<.05). In addition, RTV was lower in CAD-CAM custom abutments compared to ready-made ones (Student t-test, P<.05). Conclusion: It is considered that domestically manufactured CAD-CAM custom abutments have similar fit at the fixture abutment interface and it could be used clinically. However, RTV of CAD-CAM custom abutments should be improved for the increase of clinical application.

• Journal of Popular Narrative
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• v.26 no.2
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• pp.251-276
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• 2020

The purpose of this article is to critically read Globalizing Borderlands Studies in Europe and North America to examine trends in border studies conducted so far in Europe and North America and to discuss the expandability and limitations of the narrative. It introduces a variety of case studies covering the borderlands of Europe and North America from ancient to modern times. It consists of a total of 10 chapters, in addition to the introduction chapter to clarify the purpose and definition of the collaboration and the short conclusion chapter on the prospects for the future of borderlands studies. This volume has some important implications for current borderland research in two main respects. First, it can introduce us we the areas and targets that the leading researchers from European and North American academia (usually the United States') have paid attention to. It also examines the current status of borderland research and predicts whether it will be possible to study various border areas where exist in other regions (especially in Asia) based on accumulating academic achievements, as well as the possibility of expansion of so-called 'globalization'. Second, it introduces the borderland as a conceptual space, beyond the border area as a physical space that is commonly thought of when it comes to 'border'. Cases of "conceptual borderlands" can be applied to a number of topics ranging from an individual's identities to the methods of governance, religions, economies, social institutions, families, labor issues, public health services and gender issues. There are, however, also some questions to be noted in the volume: the lack of consistent use of terminology, which can be considered general problems of collaboration studies; the fact that the authors still tend to understand borderlands within the imperialist discourse, perhaps because of their academic background is situated mainly in Europe and North America; the borderlands cases described here as the areas of conflict and struggle only. Nevertheless, the book is of significance in that it suggests a possibility of various borderlands studies and helps us to have better understanding of the current geopolitical situation imposed on the Korean Peninsula, which is located on the borderland between the continental and maritime powers.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.259-271
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• 2013

The purpose of this study was to make the stress distribution produced by simulated different load under two types of internal connection implant system (stepped and tapered type) by means of 3D finite element analysis, The finite element model was designed with the parallel placement of the one fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st molar. Two models were loaded with 200 N magnitude in the vertical direction on the central position of the crown, the 1.5 mm and 3 mm buccal offset point from the central position of the fixture. The oblique load was applied at the angle of $30^{\circ}$ on the crown surface. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual dimension. The results were as follows; 1. The loading conditions of two internal connection implant systems (stepped and tapered type) were the main factor affecting the equivalent bone strain, followed by the type of internal connections. 2. The stepped model had more mechanical stability with the reduced max. stress compared to $11^{\circ}$ tapered models under the distributed oblique loading. 3. The more the contact of implant-abutment interface to the inner wall of implant fixture, the less stress concentration was reduced.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.576-581
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• 2016

해양환경에서 큰문제가 되고 있는 아주 작은 크기의 플라스틱 입자인 미세플라스틱(Microplastic)은 잔류성이 크고 생물축적성이 있는 잔류성 유기오염 물질(POP)을 잘흡착하여 해양환경과 먹이사슬에 지대한 피해를 끼친다. 본 연구에서는 해양에 존재하는 대표적인 미세플라스틱 uPVC와 입자상의 잔류성 유기오염 물질 PAH를 원형 실린더로 가정하여 해양 환경에서 침강하고 있는 미세플라스틱이 잔류성 유기오염 물질에 의해 오염될 가능성을 알아보았다 이를 위해 표층및 심층수 환경에서 반지름에 따른 충돌효율과 접촉 시간을 구하여 두 실린더가 접촉할 시간의 기댓값인 기대 접촉시간을 계산하였다.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.65-72
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• 2011

Purpose: The purpose of this study was to evaluate the level of electro-chemical corrosion and surface roughness change for the cases of Ti abutment connected to restoration made of base metal alloys. Materials and methods: It was hypothesized that Ni-Cr alloys in different compositions possess different corrosion resistances, and thus the specimens ($13{\times}13{\times}1.5\;mm$) in this study were fabricated with 3 different types of metal alloys, commonly used for metal ceramic restorations. The electrochemical characteristics were evaluated with potentiostat (Parstat 2273A) and the level of surface roughness change was observed with surface roughness tester. Paired t-test was used to compare mean average surface roughness (Ra) changes of each specimen group. Results: All specimens made of nickel-chromium based alloys, average surface roughness was increased significantly (P < .05). Among them, the Ni-Cr-Be alloy ($0.016{\pm}.007\;{\mu}m$) had the largest change of roughness followed by Ni-Cr ($0.012{\pm}.003\;{\mu}m$) and Ni-Cr-Ti ($0.012{\pm}.002\;{\mu}m$) alloy. There was no significant changes in surface roughness between each metal alloys after corrosion. Conclusion: In the case of galvanic couples of Ti in contact with all specimens made of nickel-chromium based alloys, average surface roughness was increased.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.699-721
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• 1996

브로네마르크가 골유착성 임플랜트를 소개한 이래로, 현재 골유착성 임플랜트에 의한 치료는 안전하고 안정적인 방법으로 여겨지고 있다. 골유착성 임플랜트를 이용한 초기의 치료는 무치악 환자의 저작기능 회복에 중점을 두어 왔다. 그러나 현재는 환자와 시대의 요구에 따라서 심미성이 주요한 관심사가 되었다. 그래서 표준 지대주보다 더 심미적인 지대주 시스템들이 개발되었다. 다양한 직경의 임플랜트 고정체에 관한 임상가들의 요구에 의해 직경 이 큰 고정체가 생산되기 시작했으며, 5mm의 직경을 갖는 고정체가 그 예이다. 골유착성 임플랜트를 사용하여 보철치료를 할 때, 골과 고정체의 계면은 보철물과 지대주에 가해지는 교합력을 인접골에 전달하게 되며, 이것은 계면에 생물학적인 반응을 야기할 수 있다. 임플랜트의 형태는 골흡수와 같은 바람직하지 않은 반응을 일으키지 않도록 고안되어야 하며, 임플랜트 자체가 교합력을 견딜 수 있어야 한다. 그러므로 골유착성 임플랜트 시스템을 임상에 사용하려고 할 때 이것의 생역학적 분석은 반드시 필요하다. 본 연구에서는 삼차원 유한요소분석적 방법을 사용하여 3.75mm직경을 갖는 고정체에 표준 지대주, 이세티콘 지대주, 마이러스콘 지대주를 연결한 모델과 5mm 직경을 갖는 고정체에 표준 지대주를 연결한 모델에 각각 수직하중, 경사하중, 수평하중을 가했을 때의 응력분포를 비교하였다. 본 연구의 결과는 다음과 같다. 1. 모든 모델에서 금나사의 경부, 금원주, 지대주에 응력의 집중이 일어났다. 2. 임플랜트 고정체에서는 고정체 상방 2/3, 그리고 지대주와 접촉하는 고정체 상면에서 응력의 집중이 관찰되었다. 3. 골에서는 상부 피질골에 응력의 집중이 관찰되었으며, 해면골에서는 두드러진 응력의 집중을 보인 부위는 없었으나 고정체의 근단부 주위 해면골에서의 응력값이 비교적 높았다. 4. 5mm 직경의 고정체를 사용하지 않은 모델 중에서, 표준 지대주를 사용한 경우가 가장 응력분산에 유리하였으며 마이러스콘 지대주를 사용한 경우가 가장 불리하였다. 5. 3가지 하중 조건하에서 수평하중과 경사하중의 경우가 수직하중의 경우보다 더 높은 응력값이 관찰되었다. 6. 응력값은 골에서보다 임플랜트 내부에서 훨씬 높았다.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.179-195
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• 2010

In the internal connection system, the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. The purpose of this study was to assess the loading distributing characteristics of three different abutments for GS II$^{(R)}$ implant fixture(Osstem, Korea) under vertical and inclined loading using finite element analysis. Three finite element models were designed according to three abutments; 2-piece Transfer$^{TM}$ abutment made of pure titanium(GST), 2-piece GoldCast$^{TM}$ abutment made of gold alloy(GSG), 3-piece Convertible$^{TM}$ abutment with external connection(GSC). This study simulated loads of 100N in a vertical direction on the central pit(load 1), on the buccal cusp tip(load 2) and $30^{\circ}$ inward inclined direction on the central pit(load 3), and on the buccal cusp tip(load 4). The following results were obtained. 1. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture and lower stress was taken at the cancellous bone. 2. When off-axis loading was applied, high stress concentration observed in cervical area. 3. GSG showed even stress distribution in crown, abutment and fixture. GST showed high stress concentration in fixture and abutment screw. GSC showed high stress concentration in fixture and abutment. 4. Maximum von Mises stress in the surrounding bone had no difference among three abutment type. In GS II$^{(R)}$ conical implant system, different stress distribution pattern was showed according to the abutment type and the stress-induced pattern at the supporting bone according to the abutment type had no difference among them.

• Korean Journal of Dental Materials
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• v.44 no.4
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• pp.329-336
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• 2017

This study evaluates the machining accuracy of the custom abutment design according to the selected convergence angle and radius of curvature value in the CAD program. Ten custom abutments were designed based on dental CAD. And then, the fabricated custom abutment was scanned ten times using a contact scanner. The data of the scanned custom abutment was saved as "Test STL" file. The Geomagic studio software was used to superposition each exported as an "Test STL" file with the CAD-reference-model STL file (CRM) specified by the same name. In the experimental results, the A8 group (convergence angle $8^{\circ}$) showed lower error than the A4 group (convergence angle $4^{\circ}$) . In addition, the higher the radius of curvature, the less error in the top and chamfer regions of the custom abutment (p< 0.05). Overall, the convergence angle and radius of curvature value in the custom abutment design were found to affect the machining accuracy.