• Journal of Periodontal and Implant Science
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• 제26권4호
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• pp.967-987
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• 1996

The present study was to evaluate the healing patterns of guided tissue regeneration( GTR) using resorbable $Vicryl^{(R)}$(polyglactin 910) mesh and nonresorbable expanded polytetrafluoroethylene(ePTFE) membrane with or without bone grafting using autogeneous bone and demineralized freeze-dried bone allograft(DFDBA) in the grade II furcation defects. Mucoperiosteal flaps were reflected buccally in the mandibular 2nd, 3rd and 4th premolar areas and furcation defects were created surgically by removing $5{\times}6mm$ alveolar bone in 4 dogs. Root surfaces were thoroughly debrided of periodontal ligament and cementum, and notches were placed on root surface at the most apical bone level. In the right and left mandibular quadrant, each tooth was received $Vicryl^{(R)}$ mesh(ACE Surgical Supply Co., USA) only, $Vicryl^{(R)}$ mesh with DFDBA, $Vicryl^{(R)}$ mesh with autogeneous bone grafts, ePTFE membrane($Core-tex^{(R)}$ membrane, W.L. Gore & Associates Inc., USA) only, ePTFE membrane with DFDBA or ePTFE membrane with autogeneous bone grafts. For the fluorescent microscopic examination, fluorescent agents were injected at 2, 4 and 8 weeks after surgery. Four weeks after surgery, 2 dogs were sacrificed and ePTFE membranes were removed from remaining 2 dogs, which were sacrificed at 12 weeks after surgery. Undecalcified tissues were embedded in methylmethacrylate and $10{\mu}m$ thick sections were cut in a buccolingual direction. These sections were stained with hematoxylin-eosin stain and Masson's trichrome stain, and evaluated by descriptive histology and linear measurements. The results were as follows : 1) $Vicryl^{(R)}$ mesh group showed less connective tissue attachment than ePTFE membrane group. 2) The combination of GTR using $Vicryl^{(R)}$ mesh and osseous grafts resulted in new attachment and new bone formation more than GTR using $Vicryl^{(R)}$ mesh only. 3) GTR using ePTFE membrane, with or without osseous grafts, enhanced periodontal regeneration. 4) Root resorption and dentoalveolar ankylosis were observed in the areas treated with the combination of GTR and DFDBA. It was suggested that the effect of adjunctive bone grafting in GTR procedure depends on the materials and the physical properties of barrier membranes. $Vicryl^{(R)}$ mesh performed a barrier function and the use of adjunctive bone grafting may enhance the periodontal regeneration.

• 대한전자공학회논문지SD
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• 제45권5호
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• pp.19-25
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• 2008

본 연구에서는 유기반도체인 펜타센과 소스-드레인 금속전극사이에 $C_{60}$을 홀주입층으로 적용한 유기박막트랜지스터를 제작하여 $C_{60}$을 삽입하지 않은 소자와의 전기적특성을 비교하였다. $C_{60}/Au$ 이중전극을 사용한 소자의 경우 Au단일전극을 사용한 소자와 비교하였을 때 전하이동도는 0.298 $cm^2/V{\cdot}s$에서 0.452 $cm^2/V{\cdot}s$ 문턱전압의 경우 -13.3V에서 -10.8V로 향상되었으며, contact resistance를 추출하여 비교하였을 경우 감소함을 확인할 수 있었다. 이러한 성능의 향상은 $C_{60}$을 Au와 pentacene 사이에 삽입하였을 경우 Au-pentacene 간의 원하지 않는 화학적 반응을 막아줌으로써 홀 주입장벽를 감소시켜 홀 주입이 향상되었기 때문이다. 또한 Al을 전극으로 적용한 OTFT도 제작하였다. 기존에 Al은 OTFT에 단일전극으로 사용하였을 경우 둘간의 높은 홀 주입장벽으로 인해 채널이 거의 형성되지 않았으나, $C_{60}/Al$ 이중전극을 사용한 소자의 경우 전하이동도와 전류점멸비은 0.165 $cm^2/V{\cdot}s$, $1.4{\times}10^4$ 으로써 Al를 단일전극으로 사용하는 소자의 전기적 특성에 비해 크게 향상되어진 소자를 제작할 수 있었다. 이는 $C_{60}$과 Al이 접합시에 interface dipole의 형성으로 Al의 vacuum energy level이 변화로 인한 Al의 work function이 증가되어 pentacene과 Al간의 hole injection barrier가 감소되었기 때문이다.

• 생명과학회지
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• 제15권2호
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• pp.267-272
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• 2005

본 연구는 화장품에서 사용되는 다양한 자극원에 대한 자극완화제로서의 세라마이드를 구성성분으로 하는 나노리포좀의 잠재적 가능성을 알아보고자 하였다. 세라마이드는 인체로부터 수분 손실을 막고, 외부의 물리적, 화학적, 그리고 미생물에 의한 손상으로부터 신체를 보호함으로써 인간의 생리작용에 있어 중요한 부분을 담당하는 것으로 알려진 표피 투과 장벽의 주요한 구조적 구성 성분이다. 본 연구 결과에 의하면 피부 장벽 기능 강화와 자극완화 효과가 제형 내에 단순히 분산된 세라마이드보다 세라마이드를 구성성분으로 하는 나노리포좀을 함유하는 경우 보다 우수하게 나타났다. 그리고, 자극원으로서 제형 내 함유되어 있는 젖산의 피부 투과도에 있어서 세라마이드를 구성성분으로 하는 나노리포좀의 영향을 평가하기 위해 무모 생쥐에서 얻어낸 피부 막으로 horizontal franz diffusion cells을 이용한 in vitro 피부 투과 시험을 수행해 보았다. 시험 결과, 세라마이드로 구성되 나노리포좀의 항자극 효과는 자극원의 피부 투과도를 감소시키는 것으로 확인하였다. 결론적으로, 본 연구에서는 새로운 자극완화 시스템의 개발이 가능하였고 이러한 세라마이드를 구성성분으로 하는 나노리포좀을 화장품에 적용 가능하였다.

• 구강회복응용과학지
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• 제28권2호
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• pp.201-212
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• 2012

임플란트 주위조직과 치아 주위조직은 조직학, 형태학적으로 유사한 면이 있다. 특히 functional ankylosis라 불리는 티타늄과 연조직의 직접적인 상피부착은 치아주위 조직의 접합상피처럼 염증세포의 치근단으로의 이행 및 그로 인한 골흡수를 막는 역할을 한다. 그러나 반복적인 지대주의 착탈은 임플란트 주위 연조직의 mucosal barrier를 파괴하여 골흡수를 야기할 수 있다. 만일 지대주의 반복적인 착탈 없이 수술 시에 보철 지대주를 채결한다면 골흡수의 양을 줄일 수 있을 것이다. 이는 기존의 수술방법으로는 한계가 있었으나 Cone Beam Computed Tomography(CBCT)를 이용한 guided surgery를 이용함으로써 임플란트 식립의 3차원적 정확성의 비약적인 향상으로 이런 술식이 가능하게 되었다. 본 증례는 정밀한 CBCT를 통한 분석 후 지르코니아 맞춤 지대주를 미리 제작하고 수술 시에 즉시 지대주와 임시보철물을 연결한 경우로 임상적으로 만족할만한 결과를 얻어 이를 보고하는 바이다.

• 폴리머
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• 제36권4호
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• pp.478-485
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• 2012

Bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride(BTDA)와 1,3-bis(3-aminophenoxy)benzene(BAPB) 단량체를 사용하여 중합한 폴리아믹산(poly(amic acid))에 용액 삽입법을 이용해서 다양한 함량의 유기화 점토를 넣은 후 열 이미드화 방법을 통해 투명한 나노복합체 polyimide(PI) 필름을 합성하였다. 0-1.5 wt%의 다양한 함량의 유기화점토를 포함하는 복합체 필름을 제조한 후, 필름의 광 투과성, 모폴로지, 그리고 가스차단성을 각각 측정하였다. 1.0 wt%의 Cloisite 30B가 포함된 복합체에서 가장 우수한 가스차단성이 측정되었으며, 유기화 점토의 함량이 증가하게 되면 가스차단성은 오히려 감소하였다. PI 복합체 필름은 우수한 광 투과성을 가지며 대체로 무색을 나타내었다. 하지만 점토의 함량이 증가함에 따라 광 투과성은 조금씩 감소하였다. Cloisite 30B가 포함된 투명한 PI 복합체 필름의 광 투과성과 가스차단성을 더 자세히 연구하기 위하여 100-140%까지 다양한 비율로 이축연신하였다. 120% 이상 연신된 PI 복합체 필름에서 고분자 매트릭스에 점토가 균일하게 분산되어 박리되었음을 확인 하였으며, 가장 높은 가스 차단성은 130%로 이축연신된 필름에서 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.32-32
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• 2009

Silicon carbide (SiC) is a wide-bandgap semiconductor that has materials properties necessary for the high-power, high-frequency, high-temperature, and radiation-hard condition applications, where silicon devices cannot perform. SiC is also the only compound semiconductor material. on which a silicon oxide layer can be thermally grown, and therefore may fabrication processes used in Si-based technology can be adapted to SiC. So far, atomic force microscopy (AFM) has been extensively used to study the surface charges, dielectric constants and electrical potential distribution as well as topography in silicon-based device structures, whereas it has rarely been applied to SiC-based structures. In this work, we investigated that the local oxide growth on SiC under various conditions and demonstrated that an increased (up to ~100 nN) tip loading force (LF) on highly-doped SiC can lead a direct oxide growth (up to few tens of nm) on 4H-SiC. In addition, the surface potential and topography distributions of nano-scale patterned structures on SiC were measured at a nanometer-scale resolution using a scanning kelvin probe force microscopy (SKPM) with a non-contact mode AFM. The measured results were calibrated using a Pt-coated tip. It is assumed that the atomically resolved surface potential difference does not originate from the intrinsic work function of the materials but reflects the local electron density on the surface. It was found that the work function of the nano-scale patterned on SiC was higher than that of original SiC surface. The results confirm the concept of the work function and the barrier heights of oxide structures/SiC structures.

• Journal of Periodontal and Implant Science
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• 제32권3호
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• pp.475-488
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• 2002

The purpose of this study is to evaluate histologically the resorption and tissue response of various resorbable collagen membranes used for guided tissue regeneration and guided bone regeneration, using a subcutaneous model on the dorsal surface of the rat. In this study, 10 Sprague-Dawley male rats (mean BW 150gm) were used and the commercially available materials included acellular dermal matrix allograft, porcine collagen membrane, freeze-dried bovine dura mater. Animals were sacrificed at 2,6 and 8 weeks after implantation of various resorbable collagen membranes. Specimens were prepared with Hematoxylin-Eosin stain for light microscopic evaluation. The results of this study were as follows: 1. Resorption : Inner portion of porcine collagen membrane was resorbed a lot at 6 weeks, but its function was being kept for infiltration of another tissues were not observed. Freeze-dried bovine dura mater and acellular dermal allograft were rarely resorbed and kept their structure of outer portion for 8 weeks. 2. Inflammatory reactions : Inflammatory reaction was so mild and foreign body reaction didn't happen in all of resorbable collagen membranes, which showed their biocompatibility. 3. In all of resorbable collagen membranes, multinuclcated giant cells by foreign body reactions were not observed. Barrier membranes have to maintain their function for 4-6 weeks in guided tissue regeneration and at least 8 weeks in guided bone regeneration. According to present study, we can find all of the resorbable collagen membranes kept their function and structure for 8 weeks and were rarely resorbed. Foreign body reaction didn't happen and inflammatory reaction was so mild histologically. Therefore, all of collagen membranes used in this experiment were considered proper resorbable membranes for guided tissue regeneration and guided bone regeneration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.145-145
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• 2011

Light-emitting diodes (LEDs) based on III-nitrides compound semiconductors have achieved a high performance device available for display and illumination sector. However, the conventional c-plane oriented LED structures are still showing several problems given by the quantum confined Stark effect (QCSE) due to the effects of strong piezoelectric and spontaneous polarizations. The QCSE results in spatial separation of electron and hole wavefunctions in quantum wells, thereby decreasing the internal quantum efficiency and red-shifting the emission wavelength. Due to demands for improvement of device performance, nonpolar structure has been attracting attentions, since the quantum wells grown on nonpolar templates are free from the QCSE. However, current device performance for nonpolar LEDs is still lower than those for conventional LEDs. In this study, we discuss the potential possibilities of nonpolar LEDs for commercialization. In this study, we characterized current-light output power relation of the a-plane InGaN/GaN LEDs structures with the variation of quantum well structures. On-wafer electroluminescence measurements were performed with short pulse (10 us) and low duty factor (1 %) conditions applied for eliminating thermal effects. The well and barrier widths, and indium compositions in quantum well structures were changed to analyze the efficiency droop phenomenon.

• The Korean Journal of Pain
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• 제29권2호
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• pp.86-95
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• 2016

Background: The present study was designed to examine the functional recovery following spinal cord injury (SCI) by adjusting the parameters of impact force and dwell-time using the Infinite Horizon (IH) impactor device. Methods: Sprague-Dawley rats (225-240 g) were divided into eight injury groups based on force of injury (Kdyn) and dwell time (seconds), indicated as Force-Dwell time: 150-4, 150-3, 150-2, 150-1, 150-0, 200-0, 90-2 and sham controls, respectively. Results: After T10 SCI, higher injury force produced greater spinal cord displacement (P < 0.05) and showed a significant correlation (r = 0.813) between the displacement and the force (P < 0.05). In neuropathic pain-like behavior, the percent of paw withdrawals scores in the hindpaw for the 150-4, 150-3, 150-2, 150-1 and the 200-0 injury groups were significantly lowered compared with sham controls (P < 0.05). The recovery of locomotion had a significant within-subjects effect of time (P < 0.05) and the 150-0 group had increased recovery compared to other groups (P < 0.05). In addition, the 200-0 and the 90-2 recovered significantly better than all the 150 kdyn impact groups that included a dwell-time (P < 0.05). In recovery of spontaneous bladder function, the 150-4 injury group took significantly longer recovery time whereas the 150-0 and the 90-2 groups had the shortest recovery times. Conclusions: The present study demonstrates SCI parameters optimize development of mechanical allodynia and other pathological outcomes.

• Journal of Ginseng Research
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• 제29권4호
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• pp.206-214
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• 2005

The health function food law has been carried into effect from January 31, 2004 just after the proposal of 'a draft of a proposed law concerning the health function foods for the promotion of a nation health' on November 29, 2000 in Korea. After enforcement of health functional food law, there have been difficult market penetration with overall stagnancy of business activities and the current of health functional food within the country divided two groups. In standardized health functional foods the present condition, nutrition supplementary products (938 items) and red ginseng products (351 items) are prevalent and total 32 products are registered containing lactobacilli (297 items), glucosamine (295 items), ginseng (182 items), yeast(136 items) so on. In 2005, five products (products containing green tea extract, soybean protein, plant sterol, fructooligo sugar and Monascus sp. products are newly notified and raw material or component of total 21 products containing xylitol, teanin extract, sardine peptide are recognized as individual authorized health functional foods. Efficacies of ginseng are studied in many-sided researches but benefits of the ginseng in the health functional food law limited to 3 items (staminaresume, immune enhancement, nourishment robustness). To enlarge functionalities of ginseng it needs raw material and ingredient approval through data application to Korea Food and Drug Administration and this procedure acts as barrier of the functional food development in the ginseng industry. It is necessary to develop the authorized health functional foods for leading health functional food market in the future.