복합레진의 지연충전이 미세인장 결합강도에 미치는 영향

박현식,조영곤,박병철,김종욱,최희영,김종진,진철희,유상훈,기영재 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.3

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (μTBS) after applied the adhesive. The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces, and composite resin were constructed immediately (group 1) or 5 min., 10 min., 15 min., 20 min. and 30 min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about l ㎟. The RBS test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95 % significance level. The results suggested that the μTBS of Single-Bond to dentin was decreased when the composite resin was constructed 20 min. and 30 min. after Single-Bond was applied. But the μTBS of One-Step was not affected by delayed composite resin filling.

상아질에 적용된 재 습윤제가 미세인장 결합강도에 미치는 영향

강희영,조영곤,김종욱,박병철,유상훈,진철희,최희영,기영재 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.2

This study investigated that the effect of rewetting agent on dentinal microtensile bond strength (μTBS). Human molars were sectioned to expose the superficial dentin surfaces. Samples were divided into two groups according to type of adhesives-Single Bond (S) and One-Step (0)], and again subdivided into five groups by different dentin surface treatment-dry for 15s (D) , blot dry (BD) or dry for 15s, and rewet with different rewetting agents[distil1ed water (DW), Gluma Desensitizer (GD) and Aqua-Prep (AP)]for 30s. After application of adhesive, composite resin was built up on the bonding surface. Each tooth was sectioned to obtain stick with 1mm^(2) cross sectional area and the μTBS was determined by EZ test. In the S group, the mean μTBS of GD, AP and BD group was significantly higher than that of DW and D group (p < 0.05). In the 0 group, the mean μTBS of AP, GD, BD and DW group was significantly higher than that of D group (p < 0.05). The data suggested that Gluma Desensitizer and Aqua-Prep could be successfully used as rewetting agents, and Distilled water could be acceptable in aceton based adhesive system only.

북한산국립공원 북한산성-인수봉 지역의 산림군집구조

추갑철 ( Gab Cheul Choo ),엄태원 ( Tae Won Um ),김갑태 ( Gab Tae Kim ),박삼봉 ( Sam Bong Park ),안효현 ( Hyo Hyeon An ),김남호 ( Nam Ho Kim ),김희정 ( Hee Jung Kim ) 한국환경생태학회 2008 한국환경생태학회지 Vol.22 No.2

북한산 국립공원지역의 식생구조를 파악하고자, 북한산성에서 인수봉에 이르는 지역에 16개의 방형구(2500㎡)를 설정하여 식생을 조사하였다. 식물군집을 분류한 결과 16개 조사구는 신갈나무 혼효림 군집, 소나무-신갈나무 군집, 신갈나무 우점군집의 3개 군집으로 분류되었다. 북한산 국립공원내 북한산성에서 인수봉에 이르는 지역의 우점수종은 신갈나무로 나타났다. 수종간의 상관관계는 신갈나무와 진달래, 신갈나무와 개옻나무, 진달래와 철쭉, 노린재나무와 철쭉, 당단풍과 함박꽃나무 등의 수종들 간에는 높은 정의상관이 인정 되었고, 물푸레나무와 진달래, 노간주나무와 당단풍, 쪽동백나무와 당단풍 등의 수종들간에 부의 상관이 비교적 높은 편이다. 조사지의 군집별 종 다양성도는 1.23 6~1.319의 범위로 다른 국립공원들의 능선부 식생에 비하여 비교적 높게 나타났다. To investigate the vegetation structure of the region from Bukhansanseong to Insubong in Bukhansan National park, 16 plost(2500㎡) set up with random sampling method were surveyed. Three groups Quercus mongolica -Mixed Broad Ieaved community, Pinus densiflora -Quercus mongolica community, Quercus mongolica community was classified (or communities were classified) by cluster analysis. Quercus mongolica were found as a major woody plant species in Bukhansan National park region. High positive correlation were proved between Quercus mongolica and Rhododendron; Quercus mongolica and Rhus tricocarpa; Rhododendron mucronulatum and Rhododendron schlippenbachi; Symplocos chinensis and Rhododendron schlippenbachii; Acer pseudosieboldianum and Magnolia sieboldii, and relatively high negative correlation was proved between Fraxinus rhynchophylla and Rhododendron mucronulatum; Juniperus rigida and Acer pseudosieboldianum; Styrax obassia and Acer pseudosieboldianum. Species diversity(H`) of investigated groups were ranged from 1.236~1.319 and it was relatively high compared to those of the ridge area of other national parks.

施工過程 및 設計過程에 補正된 高層建物 垂直構造材의 地震荷重에 의한 影響比較

박진영,정은호,김희철 경희대학교 산학협력기술연구원 1998 산학협력기술연구논문집 Vol.4 No.-

Increased height of buildings causes severe shortening of vertical structural members due to the accumulated axial load. It not only decreases the serviceability of a structure but also affect significantly the stability of a structure itself due to the secondary stress. The main purpose of estimating the shortening of vertical structural members is to compensate the differential shortening of adjacent members. This paper presents the comparison of stresses between the vertical structural members compensated during construction process and the non-compensated vertical structural members under the seismic load and represents that the precise compensation of structural members is important.

CDMA기반 IMT-2000 시스템에서 Processing Gain에 따른 최대 가입자 용량 분석

이철희,양원일,박종안 조선대학교 전자정보통신연구소 2001 電子情報通信硏究所論文誌 Vol.4 No.2

본 논문에서는, 현재 상용되고있는 디지털 셀룰러와 PCS를 기반으로 IS-98A와 J-STD-018 규격에 준하는 이동 통신용 수신 시스템의 고주파부 파라미터 성능을 분석하고, 앞으로 상용화될 IMT-2000 수신시스템의 잡음지수, 데이터 전송률에 따른 처리이득, 처리이득에 따른 단말기 잡음지수, 처리이득에 따른 최대 가입자수를 예측하는데 주안점을 두고 분석하였다. 시뮬레이션 환경은 CDMA 2000의 선두주자인 퀄컴사와 NTT에서 주장하는 전송대역폭을 1.25㎒, 5㎒, 10㎒, 20㎒로 하고, 2세대 이동통신의 데이터 전송속도 보다 10~200배 빠른 속도를 요하는 데이터 전송률을 이동자동차 환경에서 144Kbps, Outdoor 보행자 환경에서 384Kbps, Indoor office 환경에서는 2Mbps로 각각 분류하여 시뮬레이션 하였다. 시뮬레이션 결과는 확산신호 대역폭과 데이터 신호 대역폭이 CDMA나 PCS에 비해 넓어짐에 따라 수신감도가 낮아짐을 알 수 있었다. 확산 신호 대역폭이 20MHz일 경우 IMT2000에서는 최대 사용자수가 32명인 CDMA 이동자동차 환경과 비교해 약 2명 정도 증가됨을 보였고, 이동 보행자 환경에서는 약 13명, 고정사무실 환경에서는 2.5명 정도의 최대 가입자 수를 나타내었다. In this paper, we analyse the parameter performance of high frequency part of receiving system for mobile telecommunication comparable to IS-98A and J-STD-018 specification based on commercially available digital cellular and PCS, and anticipate the performance such as processing gain of IMT-2000 receiving system, receiving sensitivity according to the data processing rate, maximum capacity according to the processing gain. The simulation environments are 1.25 MHz, 5 MHz, 10 MHz, 20 MHz of transmission bandwidth recommended by Qualcomm and NTT, the leading company in CDMA 2000, and we classify data transmission rate of IMT-2000 which requires more higher speed of 10~ 200 times than data transmission speed of second generation mobile communications into three cases as in moving vehicle environment of 144Kbps, outdoor pedestrian environment of 384Kbps, indoor office environment of 2Mbps, and simulate that. Simulation results show that the receiving sensitivity is decreased according that bandwidths of spread-spectrum signal and data signal are widen than CDMA and PCS. When the bandwidth of spread-spectrum signal is 20MHz, the maximum capacity of IMT-2000 is 34 user, and this result show that the capacity is increased about 2 user in CDMA moving vehicle environment that the maximum capacity is 32 user, 13 user in moving pedestrian environment, and 2.5 user in indoor office environment.

악골에 발생한 악성 섬유성조직구종 2례

정종철,최홍란,오희균,박준아,류선열,이종호,김영운,정숭룡 大韓顎顔面成形再建外科學會 1995 Maxillofacial Plastic Reconstructive Surgery Vol.17 No.3

Malignant fibrous histiocytoma rarely occurs in the jaws. Although the histogenesis of this tumor remains controversal, it is best regarded as a primitive and pleomorphic nature reflected by collagen production and occasional phagocytosis. It is common for metastatic foci to appear in lung and regional lymph node. There are variable treatments such as radiotherapy, surgical excision or combination, therapy of surgical excision, chemotherapy and radiotherapy. With the review of literatures, the authors report the clinical study of two cases of malignant fibrous histiocytoma of the jaw.

Stochastic Reward Nets을 이용한 통신 프로토콜 검증기법에 대한 연구

노철우,박현희,윤현주 신라대학교 자연과학연구소 1999 自然科學論文集 Vol.6 No.-

In this paper, we describe validation techniques of communication protocol using Petri Nets. The Techniques which can validate protocol design specification written by SDL are constructed and protocol models are developed. Validation technique steps are as follows : SDL specifications are transformed into SRN, from which reachability graghs are obtained. By analyzing the graphs, validation properties such as reachability, boundness and liveness as well as logical errors in design are verified. SRN models for timer and retransmission, essential components of protocol are developed using SRN properties such as cardinality, multiple inhibitor arc, timed and immediate transitions.

고강도 콘크리트 디스크를 이용한 혼합모드 파괴에 관한 연구

진치섭,김희성,박현재,김민철 부산대학교 생산기술연구소 2000 生産技術硏究所論文集 Vol.59 No.-

RILEM 위원회가 제시한 3점 휨 시험은 하중-변위곡선 형상이 불규칙하고 안정된 균열 발생 후 최종균열이 발생하기 때문에 정확한 파괴인성을 구하는 것은 어렵다. 그러나, 디스크 시험은 균열 개시 하중만 알면 쉽게 파괴인성을 구할 수 있다. 중앙에 노치가 있는 고강도 콘크리트 디스크를 실험하여 실험결과와 유한요소에 의한 결과를 비교하였다. 또한, 실험에 의한 파괴 포락선과 이론에 의한 파괴 포락선도 비교하였다. It is difficult to obtain accurate fracture toughness values by RILEM committees proposed three point bend test(TPB) because the shape of load-deflection curve is irregular and final crack propagation of occurs after some slow stable cracking. However, for disk test, fracture toughness is easily obtained from crack initiation load. We examined the center notched high strength concrete disk and the experimental results were compared with the results by finite element analysis(FEA). Also, we compared experimental

초음파 반사 패턴과 주파수 대역 분할 신호처리를 이용한 다층구조인 노내 간극 측정

구길모,심철무,김종환,김상백,김희동,박치승 한국비파괴검사학회 2000 한국비파괴검사학회지 Vol.20 No.4

모의 원자로내 용융물 냉각 실증 실험 결과 용융물 Al₂O₃/Fe themite 와 lower head vessel사이에 간극이 발생된다. 간극을 정량적으로 측정하기 위한 기존의 초음파 방법은 구조물의 복잡성과 2300℃ 에서 용융되는 thermite Al₂O₃/Fe, Al₂O₃의 영향으로 발생되는 lower head의 열영향부위(HAZ)의 금속학적인 결정입자 크기의 변화로 결정 계면으로부터 발생되는 잡음신호와 초음파 산란, 감쇠, 모드 변환 등이 발생되어 신뢰성이 떨어지고 있다. 간극을 정량적으로 측정하기 위해서 thermite와 lower head 사이에 물이 체워진 형태의 즉 고체, 액체, 고체의 다층구조에서 초음파의 진행 및 반사 형태를 분류 및 분석하였다. 결정립의 잡음을 억제하기 위하여 주파수대역의 확률 처리 방식인 PT(polarity threshold) 알고리즘을 이용하여 약 6dB 신호 대 잡음비의 개선효과를 가져왔다.

하수관거의 침투수/유입수(Ⅰ/Ⅰ) 특성에 관한 연구 : 경남 H군을 중심으로

김종오,최연돈,박희철 경상대학교 생산기술연구소 2002 工學硏究院論文集 Vol.2 No.-

Infiltration/Inflow(I/I) is the major deterrent to the successful performance of the municipal sewer and the treatment system. An excessive I/I in the combined sewer system can hydraulically overload the sewer lines and the wastewater treatment plants. The purpose of this study was to investigate and analyze the I/I characteristics in order to evaluate the sewer system in the rural study area. Eight sub-catchments of the combined sewer system were monitored during two months for flowrate, pH, DO, SS, BOD, COD_Mn, COD_cr, T-N, T-P. As the results, the variations in wastewater flows were basically following a diurnal flow pattern. Minimum flows occured during the early morning hours when water consumption was lowest and when the base flow consisted of infiltration and small quantities of wastewater. The first peak flow occured in the late morning just after the peak morning water use. A second peak flow generally occured in the early evening. The I/I were related to the type of area existing in the sub-basin. During a dry weather period, the I/I were observed to be 22~70% of the average flow. Based on the results of investigation, the repair priority of the sewer system was showed according to the average I/I per the average wastewater flowrates and the I/I per drainage area.