• 제목/요약/키워드: Level set methods

검색결과 1,050건 처리시간 0.03초

環境汚染의 解決을 위한 綜合科學的 接近方法 (I) (An Interdisciplinary Approach for the Solution of Enviromental polution)

  • 신현덕
    • 한국표면공학회지
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    • 제12권3호
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    • pp.207-216
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    • 1979
  • Environmental pollution or contaminations caused by various kinds of pollutants have become one of most serious problems of our time. Environ mental pollution is the unfavoralble alteration of our surroundings, through direct or indirect effects of changes in energy patterns, rediation levels, chemical and physical constitution and abundances of organisms. These changes may affect humans directly or through their supplies of water and of agicultural and other biological products, their physical objects or possessions, or their opportunities for recreation and appreciation of nature. Pollutants that meet the criteria of this definition of environmental pollution are numerous: gases (such as sulfur dioxide and nitrogen oxides) and paniculate matter (such as smoke particles, lead aerosols, and asbestos) in the atmosphere; pesticides and radioactive isotopes in the atmosphee and in waterways; sewage, organic. chemicals, and phosphates in water; solid wastes on land; excessive heating (thermal pollution) of rivers and lakes; and many others. Some of these pollutants are introduced into the environment naturally, others by human actions, and most in both ways. Our major concer is with environmental pollution resulting wholly or largely as a by-product of human activities, because these can be controlled most readily. Environmental pollution cannot be solved by science and technology alone. It should be handled by an interdisciplinary approach with combined methods of science and technology as wen as social science disciplines for the better solution of this critical problem. In this respect, introducing "Environmental Science," a new scientific approach for the solution of environmental problems, which is now widely accepted by most developed countries of the world will be very helpful for systematization of theoretical basis for a new scientific approach to environmental pollution. Environmental science is "the study of all systems of air, land, water, energy, and life that surround Man. It includes all sciences directed to the system-level of understanding of the environment, drawing especially upon such disciplines as meteorology, geophysics, oceanography, and ecology, and utilizing to the fullest knowledge and techniques developed in such fields as physics, chemistry, biology, mathematics and engineering as well as many social science disciplines, such as economics, such as economics, law, political science and public administration." The components of this discipline are not new, for they are drawn from existing areas of science within biology chemistry, physics, and geoscience. What is really new about environmental science, however, is it siewpoint - its orientation to global problems, its conception of the earth as a set of interlocking, interacting systems, and its interest in Man as a part of these systems.

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비선형 Look-Up Table을 통한 영상 화질 개선에 관한 연구 (Study on image quality improvement using Non-Linear Look-Up Table)

  • 김선칠;이준일
    • 대한디지털의료영상학회논문지
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    • 제5권1호
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    • pp.32-44
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    • 2002
  • The role of radiology department has been greatly increased in the past few years as the technology in the medical imaging devices improved and the introduction of PACS (Picture Archiving and Communications System) to the conventional film-based diagnostic structure is a truly remarkable factor to the medical history. In addition, the value of using digital information in medical imaging is highly expected to grow as the technology over the computer and the network improves. However, the current medical practice, using PACS is somewhat limited compared to the film-based conventional one due to a poor image quality. The image quality is the most important and inevitable factor in the PACS environment and it is one of the most necessary steps to more wide practice of digital imaging. The existing image quality control tools are limited in controlling images produced from the medical modalities, because they cannot display the real image changing status. Thus, the image quality is distorted and the ability to diagnosis becomes hindered compared to the one of the film-based practice. In addition, the workflow of the radiologist greatly increases; as every doctor has to perform his or her own image quality control every time they view images produced from the medical modalities. To resolve these kinds of problems and enhance current medical practice under the PACS environment, we have developed a program to display a better image quality by using the ROI optical density of the existing gray level values. When the LUT is used properly, small detailed regions, which cannot be seen by using the existing image quality controls are easily displayed and thus, greatly improves digital medical practice. The purpose of this study is to provide an easier medical practice to physicians, by applying the technology of converting the H-D curves of the analog film screen to the digital imaging technology and to preset image quality control values to each exposed body part, modality and group of physicians for a better and easier medical practice. We have asked to 5 well known professional physicians to compare image quality of the same set of exam by using the two different methods: existing image quality control and the LUT technology. As the result, the LUT technology was enormously favored over the existing image quality control method. All the physicians have pointed out the far more superiority of the LUT over the existing image quality control method and highly praised its ability to display small detailed regions, which cannot be displayed by existing image quality control tools. Two physicians expressed the necessity of presetting the LUT values for each exposed body part. Overall, the LUT technology yielded a great interest among the physicians and highly praised for its ability to overcome currently embedded problems of PACS. We strongly believe that the LUT technology can enhance the current medical practice and open a new beginning in the future medical imaging.

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복부일반촬영시 선원과 검출기간의 거리변화에 따른 영상 화질 및 피폭선량에 관한 연구 (A Study on Patients Dose and Image Quality according to Source to Image receptor Distance in Abdomen Radiography: comparison of ESD measured and DRLs in other countries)

  • 장지성;최원근;정재연;이관섭;하동윤
    • 대한디지털의료영상학회논문지
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    • 제14권2호
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    • pp.39-46
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    • 2012
  • Purpose : The purpose of this study was to reduce Entrance Surface Dose and maintain image quality by changing Source to Image receptor Distance. And we'd like to compare ESD on this study to DRLs in other contries. Materials and Methods : We used indirect DR system(Definium 8000, General Electric, USA)and phantom(ART-200X, Flukebiomedical, USA),glass dosimeters(GD-352M, Asahi Techno Glass, Japan)for this study. The imagies were obtained throuh 80kVp fixed, and different tube currents using AEC mode in $16{\times}16$(inch) field size and changing Source to Image receptor Distance from 100 cm to 130 cm per 10 cm unit. The phantom with attaching 5 glass dosimeters on abdomonal skin was set at supine and erect position as a anterioposterial projection on detector For measuring Entrance Surface Dose. Image analysis was conducted by histograms of Image J(1.46r) which was given from National Institutes of Health(NIH). Results : Due to inverse square law of distance, the tube currents were increasing 42.6 % in supine position and 32.6 % in erect position according to the change of Source to Image receptor Distance. While Entrance Surface Doses were rapidly decreasing 14.2 % in supine position and 29.4 % in erect position according to the change of Source to Image receptor Distance. As the results of histogram using Image J, pixel mean values from 100 cm to 110 cm, 120 cm and 130 cm were decreasing each 1.4%, 2.5%, 2.7%, 4.5%, 2.2 %, 5.8 % in supine, erect position. While standard deviations from 100 cm to 110 cm, 120 cm and 130 cm were increasing each 1.4 %, 2.5 %, 2.5 %, 4.0 %, 2.0 %, 4.9 % Consequently, there are no significant differences in abdomen images taken. Conclusion: As the results described above, we strongly recommend using long Sourceto Image receptor Distance than 100cm that we have been using. So, we should deliver less Entrance Surface Dose to the patients while maintaining image quality in abdomen radiography.

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디지털 환경에서 Humerus 검사 시 촬영인자 변화에 따른 선량 및 화질 평가 (Dose and Image Assessment according to Radiologic Factors Variation at Digital Humerus X-ray Examination)

  • 김성민;홍선숙;이관섭;하동윤
    • 대한디지털의료영상학회논문지
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    • 제14권2호
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    • pp.1-8
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    • 2012
  • Purpose : We aim at presenting the optimum radiologic factor through the evaluation of dose variation and of image quality through the use of a grid in Humerus examination and the change of dose because of the change of radiologic factor. Materials and Methods : We divided it in 3 cases: when using a grid or not and when using IP(Image Plate) in a digital system. Also, as fixing kVp to 70kVp it changed mAs, and fixing mAs to 10 it changed kVp, we put up resolution chart and Burger rose phantom on the acrylic phantom of 7cm (the same level of Humerus) to evaluate the dose and image. We used Image J program to evaluate the quantitative resolution of the obtained image, and made the qualitative evaluation and statistical analysis of the image saved in PACS for 20 radiologic technologist with more than 10 years of experience in order of evaluate its contrast. We used SPSS10(SPSS Inc. Chicago, Illinois) for statistical analysis. Results : We observed the analytic result of resolution by the change of kVp that it was $4.539dGycm^2$ in 60kVp and $757.472dGycm^2$ in 75kVp, which increased about 64.6% of dose, while for the resolution it had the pixel value 30.7% better with 851 in 60kVp than 651 in 75kVp. Also, we analyzed the result of resolution by the change of mAs that it was $3.106dGycm^2$ in 5mAs, and $12.470dGycm^2$ in 20mAs, which increased about 400% of dose, while for the resolution DR had 678 in 5mAs, and 724 in 20mAs that increased about 6.8% of resolution. We made the qualitative evaluation of contrast by the change of kVp that DR showed the higher quality than CR, but the contrast by the change of kVp had no special different at the moment of visual evaluation, nor statistically significant difference(P>0.05). We observed the qualitative evaluation of contraste by the change of mAs that the contrast increased as DR increased mAs, and had statistically significant difference(P<0.05). On the other hand, CR had no significant difference for more than 10mAs nor statistically significant difference(P>0.05). Conclusion : In case of some patients with radiographic exposure by the repeated examination such as emergent patient or Follow up patient, they are considered to try to limit the use of a grid, to set kVp under 65kVp in fixed mode, to select less than 10mAs and to reduce the possibility of patient being bombed.

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신경병증성 통증에 대한 자동염전침의 진통효과 및 opioid 기전 (The Effects of Automatically Controlled Rotating Acupuncture on Thermal Allodynia in a Rat Model of Neuropathic Pain: Mediation by Endogenous Opioid System)

  • 박정혁;김선광;나효석;문학진;민병일;김기홍;임성수;이순걸;이상훈
    • Journal of Acupuncture Research
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    • 제23권5호
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    • pp.23-29
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    • 2006
  • Objectives : The present study was conducted to evaluate the effects of automatically controlled rotating acupuncture (ACRA) on thermal allodynia in neuropathic pain rats, and to examine whether the endogenous opioid system mediates the effects of ACRA. Methods : For the neuropathic surgery, the right superior caudal trunk was resected at the level between S1 and S2 spinal nerves innervating the tail. Two weeks after the nerve injury, ACRA stimulation with 4 different stimulation conditions (i.e., angle and frequency of rotation: 90o+1Hz, 90o+1/4Hz, 360o+/1Hz, and 360o+1/4Hz) was delivered to the Zusanli (ST36) acupoint for 15 min. The behavioral signs of thermal allodynia were evaluated by the tail immersion test (i.e., immersing the tail in cold $(4^{\circ}C)$ or warm $(4^{\circ}C)$ water and measuring the latency to an abrupt tail movement) before and after the stimulation. In an additional set of experiments, we examined the effects of naloxone (opioid Results : ACRA stimulations under all of the conditions above significantly relieved thermal antagonist, 2mg/kg, i.p.) on the action of ACRA stimulation. allodynia. There is no difference in the anti-allodynic effects among the 4 stimulation conditions. In addition, the effect of ACRA on thermal allodynia was reversed by naloxone pretreatment. Conclusion : These results indicate that ACRA stimulations have relieving effects on thermal allodynia in neuropathic pain rats, irrespective of stimulation parameters, and that this is mediated by the endogenous opioid system.

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엄지발가락가쪽휨증의 발가락벌리기 운동 시 초음파 영상을 이용한 시각적 피드백의 효과 (The Effects of Ultrasound Imaging Visual Feedback During Toe-Spread-Out Exercise in Subjects With Hallux Valgus)

  • 강선영;정성대;심재훈
    • 한국전문물리치료학회지
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    • 제23권3호
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    • pp.21-28
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    • 2016
  • Background: The toe-spread-out (TSO) exercise has been introduced as a strengthening exercise for the abductor hallucis muscle in subjects with hallux valgus. Visual biofeedback using ultrasound imaging during exercise, may increase the ability to selectively contract the abductor hallucis muscle, compared with exercise alone. Objects: The aim of this study was to investigate the effects of ultrasound imaging visual feedback during the TSO exercise with respect to its influence on the angle of the first metatarsophalangeal joint (1st MPJ) and the cross-sectional area (CSA) of the abductor hallucis muscle in subjects with hallux valgus. Methods: Twenty-five healthy young subjects with a mean average age of 22.5 years, and a standard deviation of 2.3 years, were recruited for this study. Hallux valgus was defined as an angles greater than $15^{\circ}$ angle of 1st MPJ. Goniometric measurement was used to determine the angle of 1st MPJ. In addition, an ultrasound system was used to collect the CSA of the abductor hallucis muscle in each foot. The angle of the 1st MPJ and CSA of the abductor hallucis were measured in three positions; the resting position, during TSO exercise, and during TSO exercise in conjunction with real-time ultrasound imaging feedback. All data analyzed using a repeated analysis of variance with Bonferroni correction in order to compare the dependent variables in all three positions. Statistical level of significance was set up as p<.05. Results: The angle of the 1st MPJ was noted to be significantly reduced and the CSA of the abductor hallucis to be significantly greater during TSO exercise used in conjunction with ultrasound imaging visual feedback, compared to when the values were recorded during TSO exercise alone (p<.05). Conclusion: Based on these findings, it can be concluded that the application of ultrasound imaging visual feedback during TSO exercise is more effective in contracting selectively the abductor hallucis than the use of exercise alone.

지역사회 이동성을 측정하는 한국어판 생활공간 평가(Korean Version of the Life-Space Assessment; K-LSA)의 임상적 유용성 및 사용성 검증 연구 (Validation Study of Clinical Utility and Usability on Korean Version of the Life-Space Assessment to Assess Community Mobility)

  • 김정희;장문영
    • 대한지역사회작업치료학회지
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    • 제8권1호
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    • pp.1-10
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    • 2018
  • 목적 : 본 연구의 목적은 노인의 지역사회 이동성을 측정하는 평가도구인 한국어판 생활공간 평가(Korean Version of the Life Space Assessment; K-LSA)의 임상적 유용성 및 사용성을 검증하는 것이다. 연구방법 : 작업치료사와 물리치료사 60명을 대상으로 K-LSA의 임상적 유용성 및 사용성 검증에 관한 설문조사를 실시하였다. 설문지는 임상적 유용성에 관한 객관식 문항 및 사용성에 관한 객관식과 주관식 문항을 포함하였다. 객관식 자료 분석은 빈도 분석 및 기술 통계로 처리하였고, 사용성에 대한 주관식 문항은 항목별로 공통적인 요소를 모아 분류하여 분석하였다. 결과 : K-LSA의 임상적 유용성에 긍정적 표현인 '보통(3점)'과 '그렇다(4점)'와 '매우 그렇다'로 응답한 비율이 95~100%이었고, 문항 별 점수 분포가 3.6~4.0점으로 나타났다. 또한 K-LSA의 사용성에 대한 질문에 긍정적 표현인 '보통'과 '쉽다'와 '매우 쉽다'로만 응답한 비율은 88.3~100%이었고, 문항 별 점수 분포가 3.6~4.0점으로 나타났다. 추가적으로 사용성에 대한 개방형 질문에서 생활공간 범위 3과 4에서 기준의 모호함이 언급되었다. 결론 : K-LSA는 국내 보건의료 분야에서 지역사회 이동성을 측정하는 평가도구로 임상적으로 유용하며, 사용이 용이한 도구이다. 따라서 치료사들이 노인의 사회 참여를 증진시키고, 지역사회 이동을 위한 중재 목표를 세우고, 교육하는데 기초자료로 LSA를 활용할 수 있을 것이다.

Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material

  • Yi, Myong-Hee;Shim, Joon-Sung;Lee, Keun-Woo;Chung, Moon-Kyu
    • The Journal of Advanced Prosthodontics
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    • 제1권2호
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    • pp.63-67
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    • 2009
  • STATEMENT OF PROBLEM. Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. PURPOSE. This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. MATERIAL AND METHODS. Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material(Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. RESULTS. The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. CONCLUSION. Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

한국 골프장의 친환경적 개발에 관한 연구 (Study of Pro-environmental Development for Golf Course in Korea)

  • 김광두
    • 아시안잔디학회지
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    • 제12권1호
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    • pp.49-78
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    • 1998
  • Nowadays, there are increasing demands of golf courses and it is necessary to make more golf courses than the present. To do this, we need to improve the environmental problems with the regional inhabitants, and it is said that the first thing to be considered in developing any golf course in Korea is to preserve the environment. In this context, the purpose of this study is to set forth several design factors to lessen the negative impacts which are accompanied with the development of golf courses. 1. The present conditions of golf courses in Korea Many new golf courses have come into being, particularly since the late 1980s, and now, in the year of 1997, over one hundred of golf courses are doing their business, yet the number of golf course is still less than required. So far, over a half of them have been made in the vicinity of Seoul on account of various reasons, and this has adversely affected on our natural environment. This unreasonable development of golf courses has caused serious water pollution, landslides and the other problems. Also, the topography of Korea is not good for golf courses. Although the demands of golf courses are increasing, the suitable sites for them are very limited, and therefore it is sometimes unavoidable to make golf courses on steep hills. Consequently, in designing golf courses in Korea, the most important thing is the balance between natural environment and artificial environment. 2.Eco-friendly golf course design factors 1) The concept of eco-friendly golf courses Ecologically sustainable and sound golf courses which are made by eco-friendly approaches 2)Basic conditions of eco-friendly golf courses (1)The most suitable sites (2) Conservation of existing ground as much as possible (3)Proper use of agricultural chemicals which have great impacts on the environment (4) Reasonable use of fertilizers (5) Developing a specialized fertilizer only for grass (6) Adaptation of organic agriculture (7) Improvement of grass sorts (8) Establishing reservoirs for purifying the water from golf courses 3) Eco-friendly golf courses (1) Location-Enough area /Gentle slope/Winding ground/Including lakes or streams /Not crossing wind's main direction Facing south or southeast /Suitable soIl for grass /Good drainage /Low level of underground water (2)Course layout and design -Consideration about existing contours as much as possible -Adaptation of Scotish design trend -Various holes' configuration -Consideration toward surrounding landscapes -Reducing grass areas -Giving buffer zones -Adapting computer methods in the process of site analysis and design (3) Eco-friendly considerations in constructing and managing golf courses -Protection of wildlife -Reuse of existing forests and preservation of topsoil -Renovation of old-fashioned courses -Reducing grass areas -Purification of water -Standization of management -Strict regulations against chemicals -Recycling organic materials -Through separation of the water inside golf courses and out of bounds -Getting proper construction works done in a due time 4.Eco-friendly considerations from a viewpoint of cultural environment 1) Well-matched landscape design and events planning 2) Implement of identifications and awarding systerns 3)Acknowledgement of superintendents' qualitications in the maintenance of golf courses 4)Increasing public golf courses and keeping good relationships with the neighbors near golf courses Key words: Pro-environmental development, Golf course.

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전치부 영역 임플란트의 식립 시기에 따른 심미적 평가 (Comparative esthetic evaluation of anterior zone with immediate, early, and delay implantation)

  • 김정화;서성용;김나홍;유정현;이동운
    • 대한심미치과학회지
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    • 제26권1호
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    • pp.17-23
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    • 2017
  • 임플란트 식립시기가 심미적인 부분에 영향을 미치는 것에 대한 연관성을 평가하기 위해 전치부 영역에 식립된 34개의 임플란트 (27명 환자)를 후향적으로 조사했다. 즉시, 조기 및 지연식립으로 시기별로 그룹을 나누고 모든 환자를 보철완료 1년후에 연조직 평가를 시행했다. 통계적으로 그룹별 유의한 의미는 없었다. 식립 시기에 상관없이 만족할 만한 최종결과를 위해 다양한 골이식술과 연조직 이식술이 이루어졌다. 즉, 식립시기로 그 결과를 결정지을 수 없다는 점은 다각적인 면에서 고려사항이 요구된다는 점을 시사한다.