• 한국진공학회지
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• 제12권S1호
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• pp.113-115
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• 2003

We investigate transmission of light in nanoscale structures. We present spatial and temporal domain measurements of the dephasing of surface plasmon excitations in metal films with periodic nano-hole arrays. By probing coherent spatial SP propagation lengths of a few f1. $\mu$m and an ultrafast decay of the SP polarization on a 10 fs timescale, we demonstrate that the SP transmission peaks are homogeneously broadened by the SP radiative lifetime. The pronounced wavelength and hole size dependence of the dephasing rate shows that the microscopic origin of the conversion of SP into light is a Rayleigh-like scattering by the periodic hole array. We have experimentally studied the dephasing of surface plasmon excitations in metallic nano-hole arrays. By relating nanoscopic SP propagation, ultrafast light transmission and optical spectra, we demonstrate that the transmission spectra of these plasmonic bandgap structures are homogeneously broadened. The spectral line shape and dephasing time are dominated by Rayleigh scattering of SP into light and can varied over a wide range by controlling the resonance energy and/or hole radius. This opens the way towards designing SP nano-optic devices and spatially and spectrally tailoring light -matter interactions on nanometer length scales.

• 비파괴검사학회지
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• 제14권4호
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• pp.237-243
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• 1995

고체 시료를 대상으로 하여 silicon wafer에는 $90^{\circ}$ wedge형 진동자를 사용하고 압전재료인 $LiTaO_3$에는 interdigital transducer(IDT)를 사용하였으며, knife edge를 이용한 광학적 검지(optical probing)법을 써서 표면탄성파의 발생 및 측정하는 기법으로써 재료에서의 표면탄성파의 감쇠를 검출하는 방법을 연구하였다. IDT1 및 IDT2로는 20.8 MHz와 14.5 MHz를, $90^{\circ}$ wedge형 진동자로부터는 20.0 MHz의 표면탄성파를 발생시켰으며 표면탄성파로 생기는 표면의 굴곡을 검출하는데 He-Ne laser beam을 이용하였다. Optical chopper로 변조시킨 laser beam을 같은 주파수로 변조시킨 표면탄성파에 입사시켜 산란되는 광을 같은 주파수로 동조된 lock-in amplifier로 검출하였다. 이와 같이 함으로써 검출할 표면탄성파와 검출에 사용된 laser beam 및 측정기기인 위상감지기(Phase Sensitive Detector : PSD)를 같은 주파수로 변조하여 동기시킬 수 있었으며 측정계를 단순화하였다. IDT1, IDT2에서 발생된 표면탄성과의 감쇠계수는 각각 $0.62{\sim}0.75dB/mm,\;0.60{\sim}0.72dB/mm$였으며 wedge형 진동자에서는 $0.83{\sim}1.28dB/mm$인 값을 얻었다.

• 대한치과의사협회지
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• 제54권5호
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• pp.365-373
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• 2016

Purpose: Cemental tear is a specific type of root surface fracture characterized by a complete separation of a cemental fragment along the cementodentinal junction or a partial split within the cementum along an incremental line. It is suggested to be a factor for periodontal or periapical tissue destruction. The aim of this study is to present a diagnosis and treatment of cemental tear associated with periapical lesion with root canal treatment and regenerative periodontal surgery. Treatments: A 60-year-old male who had a history of sports trauma on the mandibular right central incisor about 10 years ago presented with apical cemental tear. Clinical examination showed a slightly dark yellowish discoloration and sinus tract that was located on the apical labial mucosa. The mobility and percussion were also assessed on the diseased tooth and recorded as $Miller^{\circ}{\phi}s$ Class II and tenderness to percussion. The probing depth was within the normal limit (<3 mm). Radiographic examination revealed a radiolucent lesion at the apical area and extended to distal aspect of the tooth along the fragment of cemental tear. After root canal treatment, periapical surgery was performed. The bony defect was exposed and then the detached root fragment was removed. Apical root resection and retrograde filling with Mineral Trioxide Aggregate (MTA) were accomplished and the bony defect was filled with deproteinized bovine bone mineral (DBBM) and covered with biodegradable collagen membrane. Results: After 9-month follow-up, healing of the mandibular right central incisor was uneventful and no swelling, purulence or pain was revealed in the associated area. Probing pocket depth was favorably stable, and the tooth mobility was decreased to the Miller's Class I. Conclusions: Apical cemental tear associated periapical lesion could be successfully treated with removal of the detached cementum in combination with apical surgery and GTR procedure.

• Journal of Periodontal and Implant Science
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• 제44권1호
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• pp.39-47
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• 2014

Purpose: Peri-implantitis, a clinical term describing the inflammatory process that affects the soft and hard tissues around an osseointegrated implant, may lead to peri-implant pocket formation and loss of supporting bone. However, this imprecise definition has resulted in a wide variation of the reported prevalence; ${\geq}10%$ of implants and 20% of patients over a 5- to 10-year period after implantation has been reported. The individual reporting of bone loss, bleeding on probing, pocket probing depth and inconsistent recording of results has led to this variation in the prevalence. Thus, a specific definition of peri-implantitis is needed. This paper describes the vast variation existing in the definition of peri-implantitis and suggests a logical way to record the degree and prevalence of the condition. The evaluation of bone loss must be made within the concept of natural physiological bony remodelling according to the initial peri-implant hard and soft tissue damage and actual definitive load of the implant. Therefore, the reason for bone loss must be determined as either a result of the individual osseous remodelling process or a response to infection. Methods: The most current Papers and Consensus of Opinion describing peri-implantitis are presented to illustrate the dilemma that periodontologists and implant surgeons are faced with when diagnosing the degree of the disease process and the necessary treatment regime that will be required. Results: The treatment of peri-implantitis should be determined by its severity. A case of advanced peri-implantitis is at risk of extreme implant exposure that results in a loss of soft tissue morphology and keratinized gingival tissue. Conclusions: Loss of bone at the implant surface may lead to loss of bone at any adjacent natural teeth or implants. Thus, if early detection of peri-implantitis has not occurred and the disease process progresses to advanced peri-implantitis, the compromised hard and soft tissues will require extensive, skill-sensitive regenerative procedures, including implantotomy, established periodontal regenerative techniques and alternative osteotomy sites.

• Journal of Periodontal and Implant Science
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• 제35권1호
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• pp.31-41
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• 2005

Fimbriae (fimA) of Porphyromonas gingivalis are filamentous components on the cell surface and are thought to play an important role in the colonization and invasion of periodontal tissue. P. gnigivalis fimA gene encoding fimbrillin, a subunit of fimbriae, has been classified into 5 genotypes (types I to V) based on the nucleotide sequences. In the present study, we examined the prevalence of these fimA genotypes in patients with dental implant and the relationship between prevalence of these genotypes and peri-implantitis. Dental plaque specimens obtained from 80 peri-implant sulci of 50 patients with dental implants were analyzed by 16S rRNA fimA gene-directed PCR assay. P. gingivalis were detected in 74.4% of the samples of the control group (healthy peri- implant sulci; probing depth<5mm) and in 92.0% of the samples of the test group (peri-implant sulci with peri-iimplantitis; probing $depth{\geqq}5mm$). Among the P. gingivalis-positive samples of the control group, the most prevalent fimA type was type I (29.3%), followed by type II (26.8%). In contrast, a majority among the P. gingivalis-positive samples of the test group was type II (56.S%), followed by type I (43.5%). TypeII fimA genotype organisms were detected more frequently in the test group and a significant difference in the occurrence of type II was observed between test and the control groups. A correlation between specific fimA types and peri-implant health status was found in type II (OR 3.545) and only a weak relationship was revealed in typeIV(OR 3.807). These findings indicate that P. gingivalis strains that possess type II fimA are predominant in peri-implant sulci with peri-implantitis and are closely associated with peri-implant health status. P. gingivalis with type II fimA may be involved in peri-implantitis.

• Journal of Periodontal and Implant Science
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• 제30권1호
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• pp.157-168
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• 2000

Periodontal surgery can be directed to remove the irritants from the tooth surface and reduce the periodontal pocket. The purpose of this study is to compare the clinical effects after between modified Widman flap and modified flap in periodontal patients. Ninety six molar area teeth of 9 patients were used. One of sextants performed a modified Widman flap, while the other side performed a modified flap. After initial periodontal therapy, the following measurements prior to surgery(baseline) were taken : pocket depth, gingival recession, clinical attachment level, tooth mobility, bleeding on probing. Also these measurements were taken at 4 weeks, 8weeks, and 12 weeks after surgery. Significant decrease of pocket depth was shown in both techniques, and the degree of decrease was significant in modified flap than modified Widman flap at 12 weeks. Significant increase of gingival recession was shown in both techniques, and the degree of increase was significant in modified Widman flap than modified flap at 4 weeks, 8 weeks, and 12 weeks. Significant attachment gain was shown in both techniques, and the degree of increase was significant in modified flap than modified Widman flap at 4 weeks, 8 weeks, and 12 weeks. Significant increase of tooth mobility was shown in both techniques at 4 weeks, but the decrease of tooth mobility was shown at 12 weeks. Greater decrease of bleeding on probing was shown in both techniques at 4 weeks. Modified flap was better than modified Widman flap in the decrease of gingival recession and the attachment gain. These results indicate that modified flap operation is better than modified Widman flap operation in the effect of periodontal treatment.

• 한국컴퓨터그래픽스학회논문지
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• 제16권3호
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• pp.41-48
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• 2010

포톤 매핑은 대표적인 전역 조명 방법으로써 광원에서 많은 수의 포톤을 방출하여 이를 이용해 사실적인 렌더링을 수행한다. 하지만 매우 많은 수의 포톤을 추적하기 때문에 실시간 렌더링이 힘들고 많은 양의 메모리를 사용하는 문제가 있다. 이러한 문제를 개선한 방법이 점진적 포톤 매핑이다. 기존의 점진적 포톤 매핑은 먼저 광선 추적법을 통해 각 광선과 물체와의 충돌 위치를 찾는다. 다음으로 포톤 추적 단계에서는 반복적으로 적은 수의 포톤을 방출하고, 충돌 위치를 중심으로 하며 고정된 반지름을 가지는 구 안에 들어오는 포톤으로 포톤의 밝기를 누적한다. 이 방법은 포톤 매핑보다 자원을 적게 소모하지만, 방출된 포톤이 임의의 방향으로 진행하기 때문에 충분한 포톤을 확보하고 부드러운 영상을 렌더링하기 위해 많은 시간이 필요하다. 이를 보완하기 위해 본 논문에서는 포톤 탐사 단계를 추가하여 구 안에 들어오는 포톤들의 분포를 계산하고 그에 따라 구의 반지름을 조절하는 방법을 제안한다. 또한 래디언스 추정 과정에 콘 필터를 적용하여 영상을 선명히 렌더링한다.

• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.116-126
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• 2022

Purpose: This study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP). Methods: A total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque. Results: From baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05). Conclusions: Applying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

• 한국응용곤충학회지
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• 제36권1호
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• pp.88-95
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• 1997

매미나방(Lymantria dispar)에서 추출된 카이로몬을 이용하여 난기생천적인 짚시알깡충좀벌(Ooencyrtus kuvanae)에 대한 유인성을 olfactormeter로 측정하였다. 매미나방알의 인편과 털에서 추출한 카이로몬은 79.9%의 유인성을 나타내어 알에서 추출한 카이로몬의 67.6%보다 높은 유인력을 나타내었다. 짚시알깡충좀벌의 탐색시간은 인편과 털의 추출물에서 115.5초 인편과 털을 제거하지 않은 알에서 113.2초로 유사하였다. 정상적으로 산란된 기주알에 대해서는 91.0%가 유인되어서 난소에서 적출한 미성숙알의 15%보다 크게 높았으며 탐침까지의 시간은 84.2초로 난수에서 적출한 알의 114.0초보다 짧았다. 생식부속샘에서 분비되는 접착물질은 88%로서 가장 높은 반응을 보였고, 탐색시간은 89.2초, 최초탐침시간은 26.8초를 나타냈다. 6종류의 유기용매를 사용하여 추출한 카이로몬을 대상으로 짚시알깡충좀벌의 유인도를 조사한 결과 n-hexane의 추출물에서 가장활발한 반응을 나타냈으며 자연난에서 우화한 것이 인공난에서 우화한것보다 3배이상 높은 반응을 보였다.

• 콘크리트학회논문집
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• 제21권2호
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• pp.153-158
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• 2009

콘크리트 표면에 4개의 전극배열을 이용한 비파괴 표면측정법을 통하여 철근의 피복을 벗겨내지 않고도 콘크리트 내 철근의 부식상태 및 철근의 배치상태를 추정할 수 있다. 표면측정법 모델링은 부식된 철근과 주위 콘크리트사이의 계면 임피던스가 콘크리트 표면에서 측정된 임피던스와 어떤 관련이 있는지를 보여준다. 본 연구에서는 콘크리트에 매립된 철근 크기와 콘크리트 피복두께 등의 탐지를 위하여 철근부식 표면측정 모델링을 이용하였다. 모델링 결과 철근 크기가 D10에서 D35로 커짐에 따라 표면임피던스 변화가 나타났으며, 또한 콘크리트 피복두께가 0.02 m에서 0.1 m로 커짐에 따라 그 변화에 대한 영향이 표면측정 임피던스를 통해 나타났다. 그러므로 표면측정법 모델링을 통하여 콘크리트 내 철근부식반응을 시뮬레이션 할 수 있으며, 동시에 철근직경과 매입 깊이 등에 대한 정보도 얻을 수 있음 알 수 있다.