• The Journal of the Petrological Society of Korea
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• v.11 no.2
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• pp.74-89
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• 2002

Rock units, relating with the Guamsan caldera, are composed of Guamsan Tuff and rhyolitic intrusions. The Guamsan Tuff consists almost entirely of ash-flow tuffs with some volcanic breccias and fallout tuffs. The volcanic breccia comprises block and ash-flow breccias of near-vent facies and caldera-collapse breccia near the ring fracture. The lower ash-flow tuffs are of an expanded pyroclastic flow phase from the pyroclastic flow-forming eruption with an ash-cloud fall phase of the fallout tuffs on the flow units, but the upper ones are of a non-expanded ash-flow phase from the boiling-over eruption. The rhyolitic intrusions are divided into intracaldera intrusions and ring dikes that are subdivided into inner, intermediate and outer dikes. We compile the volcanic processes along a single cycle of cadela development from the eruptive phases in the Guamsan area. The explosive eruptions began with block and ash-flow phases from collapse of glowing lava dome caused by Pelean eruption, progressed through expanded pyroclastic flow phases and ash-cloud fallout phases during high column collapse of pyroclastic flow-forming eruption from a single central vent. This was followed by non-expanded ash-flow phases due to boiling-over eruption from multiple ring fissure vents. The caldera collapse induced the translation into ring-fissure vents from a single central vent in the earlier eruption. After the boiling-over eruption, there followed an effusive phase in which rhyolitic magma was injected and erupted to be progressively emplaced as small plugs/dikes and ring dikes with many lava domes on the surface. Finally rhyodacitic magma was on emplaced as a series of dikes along the junction of both outer and intermediate dikes on the southwestern side of the caldela.

• 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.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.71-81
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• 2004

The purpose of this study was to compare the distributing pattern of stress on the finite element models of two units implant prosthesis with one angulated placement of two implant fixtures. The two unit implant crowns simulated to mandibular first and second molars were made. The two kinds of finite element models were designed according to angulation of fixture ($4.0mm{\times}11.5mm$) : Model 1($15^{\circ}$ buccally angulated placement of one fixture on second molar area), Model 2($15^{\circ}$ lingually angulated placement of one fixture on second molar area). Axial loads of 200N were applied to the center of central fossa and to distance of 2mm and 4mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the fixtures, and buccolingual section of implants. The results were as follows: 1. Under axial loading at the central fossa, the stress was distributed along the straight fixture except apical portion, while on buccally or lingually angulated placement, the highest stresses were concentrated in the neck portion on the opposite side of the angulated fixture. 2. With offset distance increasing, the stresses were concentrated greater in buccal neck of lingually angulated fixture than in lingual neck of buccally angulated fixture. From the above results, in designing of the occlusal scheme for implant prosthesis with the angulated fixture, occlusal contacts should be placed to distribute stress axially in maximum intercuspation and to avoid offset force during eccentric movements.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.264-273
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• 2013

The importance of the robots has emerged as the means of minimizing the casualties in the future war, and, thus, the biomimetic robots mimicking the optimized organisms has been actively studied. The robot inspired lizard is suitable for reconnaissance and the surveillance in narrow areas. In this paper, we analyzed the locomotion of a lizard by motion capture system using the infrared markers. We attached 21 markers to the joints of the lizard. By considering the measured data, we analyzed the walking motion of the lizard which trots in a sprawled posture. Moreover, we proposed the 25 dof kinematic model which was able to reproduce the gait of the lizard faithfully. The model was verified by simulations.

• The Journal of the Korean bone and joint tumor society
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• v.17 no.2
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• pp.106-110
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• 2011

In the patient who has intradural mass associated with spinal stenosis, if the operation for spinal stenosis is performed alone, the symptom may remain. We report with literature review that we achieved the successful outcome after simultaneous decompression of spinal stenosis and space occupying mass removal in the case of intradural and extradural compression. A 71-year-old female patient suffering from low back pain and radiating pain of both lower extremities admitted. In magnetic resonance imaging, spinal stenosis on L4-5 and spondylolisthesis on L5-S1 compressed dural sac and intradural space occupying mass on L4 level compressed. By posterior approach, decompression and interbody fusion were carried out. Then mass was removed with median durotomy. Pathologic diagnosis was schwannoma and the symptom was improved remarkably.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.17.2-17.2
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• 2011

모든 생물은 늙어가면서 그 생물체를 이루고 있는 생체조직들이 낡게 되고 약해지기 마련이며, 이외에도 자동차 사고 등 재해에 의해 생체 장기의 손상을 가져올 수도 있다. 또한 인간의 평균수명 연장과 함께 소득 수준이 높아지고 또한 'quality of life'를 추구하는 고령화 시대로 접어듦에 따라, 인공골, 인공치아 또는 인공 고/슬관절 등의 골조직 대체재료의 수요가 빠르게 증가하고 있다. 이와 같은 골조직 대체, 즉 골이식은 크게 자기골 이식(autografting), 동종이식(allografing), 인공재료(man-made materials)의 이식으로 구분된다. 현재 대체물질의 약 58%를 차지하고 있는 자기골 이식의 경우, 거부면역 반응이 없어 임상성공율이 80%에 달한다는 장점을 가지고 있으나, 비용이 비싸고 감염과 통증의 위험이 있다. 또한 시신으로부터 골을 이식하는 동종이식의 경우 대체물질의 약 34%를 차지하고 있는데, 성공률이 떨어지고 질병 감염의 위험이 있는 단점이 있다. 이외에 약 8%를 차지하고 있는 인공재료 이식의 경우, 파단, 독성반응, 마모, 골조직의 remodeling 등이 일어나는 단점이 있으나, 앞에서 언급한 바와 같이 그 필요성이 급격히 증가함에 따라 보다 나은 치료법과 골이식 대체물질의 개발에 많은 노력이 경주되고 있다. 2003년 6월 미국 Financial Times에 의하면, 인체내 식립형 생체재료의 세계시장 규모는 약 650억 달러에 이르며, 매년 200% 이상씩 신장하고 있다고 한다. 따라서 세계 각국의 의학, 약학, 임상학, 생명과학, 공학 등의 관련 연구 분야에서는 이 수요를 충족시키기 위한 활발한 연구활동을 펼치고 있다. 한편 인체내 식립용 임플란트의 국내 시장규모는 치과 임플란트의 경우 2006년 현재 2000억원 규모로, 정형외과, 악안면 성형외과, 이비인후과를 포함하면 소위 'bone-anchored metal implant' 영역의 시장 규모는 4~5조원에 이를 것으로 추산 되고 있다. 또한 소비 신장률 10~15%를 감안하면 향후 시장 규모는 폭발적으로 증가될 것으로 예상된다. 이에 발맞추어, 최근 들어 선진국은 물론, 국내에서도 인체내 식립을 목적으로 하는 생체재료에 관한 연구개발이 활발히 진행되고 있으며, 일부는 실용화 단계에 진입하고 있다. 본 강연에서는 금속 임플란트의 시장현황과 앞으로의 추세에 대하여 조망하고, Ti 임플란트를 중심으로 이의 생체활성을 부여하는 표면개질 필요성 및 최근의 연구개발 동행에 대해 소개하고자 한다.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.3
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• pp.319-326
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• 2012

For many years, ceramics have been used in fixed prosthodontics for achieving optimal esthetics. but, they have another use as well. Many studies today show ceramics can be used for biomaterials. In the beginning researchers made a start in the study of aluminium oxide and sapphire for biomaterial. The appearance of Zirconia began a new phase of research. Zirconia was introduced into implantology as an alternative to titanium, because of its white color, good mechanical properties and superior biocompatibility. But it is not easy to surface treatment in comparison with titanium. To overcome the limitation, interconnected porous bodies of zirconia were fabricated by sintering technique. And the technique of coating was developed. Therefore, some zirconia implants are currently available. It is thought that Research of biomaterials as a variety of puposes for the use of zirconia is looking very promising. The purpose of this paper reviews are to evaluation of zirconia as biomaterials.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2008.11a
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• pp.37-51
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• 2008

인삼은 재배적지에 대한 선택성이 매우 강한 식물이며, 기후 토양 등의 자연환경이 적당하지 않으면 인삼의 생육이 곤란하고, 생육이 가능하더라도 생산된 인삼의 형태, 품질 및 약효에서 현저한 차이를 나타내고 있다. 이러한 인삼의 식물학적 특성이 우리나라에서는 최적의 환경조건으로 인정되어 고려인삼은 세계적으로 최고의 품질로 높이 평가되는 이유이다. 하지만 실질적인 인삼의 생리활성물질에 대한 연구는 서구열강 및 일본에 의해 대다수 연구, 발표되었으며 또한 인삼의 우수성을 인정하여 넓은 영토와 수많은 과학적 지식으로 고려인삼의 우수한 품질을 앞서가려 하고 있는 것이 현실정이다. 특히 중국의 넓은 인삼재배면적에서 값싸게 생산된 인삼이 한국시장을 위협하고 있으며, 미국과 캐나다에서 수많은 연구비를 투자하여 자국삼인 화기삼의 홍보를 대대적으로 함으로서 전세계의 인삼시장의 변화를 유도하고 있고, 호주, 뉴질랜드에서도 청정인삼을 내세워 한국 및 전세계 인삼시장을 잠식해가고 있다. 이런 변화에 의하여 한때 인삼의 종주국으로 전세계의 인삼시장을 석권했던 한국의 고려인삼이 과거의 위상을 점차 잃어 가고 있는 실정이다. 따라서 인삼재배면적이 경쟁국과 비교해 상대적으로 열세인 한국의 고려인삼이 선택할수 있는 방법은 비록 생산은 적더라도 고부가가치인삼을 생산하여 명품화로 가야 할 것으로 생각된다. 명품화를 위해서는 우선 고려인삼의 효능을 밝혀 고기능성을 입증해야하고, 재배생산단계에서부터 농약, 중금속등에 노출되지 않고 병에 자유로운 청정재배를 통해 명품화를 이룩해야 하며, 특히 제품의 생산 및 유통단계에서 표준화를 통해서 전세계의 소비자가 믿고 사용할수 있도록 해야 할 것이다. 또한 인삼에만 함유된 인삼사포닌(ginsenoside)은 배당체로서 여러 미생물에 의하여 당사슬이 끊어짐으로서 새로운 사포닌이 등장하게 되는데 이러한 사포닌이 각종 함암, 면적, 치매, 관절등에 탁월한 효능을 보임으서 많은 연구들이 진행중에 있으며, 특히 인삼에만 함유된 것으로 알고 있었던 ginsenoside가 돌외(한약재명 칠엽담)에도 함유되어 있고 일부 성분은 미생물을 통해서 변환시킴으로 서 값비싼 인삼사포닌을 생장이 빠르면 비교적 값싼 돌외 사포닌으로부터 생산할수 있게 되었다. 본 세미나에서는 각종 미생물을 이용하여 인삼의 사포닌을 변환시키고 돌외 사포닌인 gypenoside를 ginsenoside로 변환시켜 대량생산할 수 있는 방법을 제시하고자 한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.2
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• pp.159-164
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• 2011

In this study, a crab robot is implemented in H/W based on four-bar linkage mechanism and Jansen mechanism, and its kinematics is analysed. A vision camera is attached to the mechanism, which makes the proposed robot a kind of biologically inspired robot for image acquisition. Three ultrasonic sensors are adopted for obstacle avoidance. In addition, the biologically inspired robot can achieve the mission appointed by a programmer outside, based on RF and Blue-tooth communication module. For the design and implementation of a crab robot, it is need to get joint variable, a foot point, and their relation. Thus, the proposed kinematic analysis is very important process for the design and implementation of legged robots.

• Korean Journal of Plant Taxonomy
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• v.40 no.4
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• pp.247-250
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• 2010

We report Polygonum plebeium R.Br. (Polygonaceae) as an unrecorded species from the Geumgang River, Buyeo-gun; Galmae-dong, Guri-si; the Chungju Reservoir, Jecheon-si; the Daecheong Reservoir, Okcheon-gun; and the Daecheong Reservoir, Daejeon, in Korea. It is distinguished from P. aviculare by pedicels that articulate in the middle and by its smooth and shiny achenes. The new Korean name, 'Ae-Gi-Ma-Di-Pul', is given considering the small-sized plant. In this study, a description and illustrations of the species and photos of the habitat are provided.