• Restorative Dentistry and Endodontics
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• 제36권5호
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• pp.385-396
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• 2011

연구목적: 본 연구는 치근벽의 전처리 개념과 접착제의 중합방법이 레진계 근관충전제의 치근단 밀폐능에 미치는 영향을 평가하였다. 연구 재료 및 방법: 3가지 다른 접착변수를 조합하여 충전한 Resilon-RealSeal 시스템의 근단미세누출을 색소침투법을 이용하여 통상의 가타퍼쳐 충전과 비교하였다. 실험군은 자가부식형 RealSeal primer와 이중중합형 RealSeal sealer를 이용하여 Resilon 충전한 SEDC군, 산부식없이 Scotchbond Multi-Purpose primer를 적용한 후 접착제는 광중합하고 Resilon을 충전한 NELC군, 및 Scotchbond Multi-Purpose의 접착강화제와 접착제를 total etch/wet bonding과 광중합의 술식을 정확하게 지켜서 Resilon을 충전한 TELC군으로 구분하였다. 대조군(GPCS)에서는 통상의 AH26 plus sealer를 사용하여 가타퍼쳐를 충전 하였다. 결과: 치아장축방향의 색소침투는 TELC군에서 GPCS군과 SEDC군에 비해 유의하게 작았다(Kruskal-Wallis test, p < 0.05). 횡단면의 미세누출 점수도 TELC군이 근첨으로부터 2 - 5 mm의 범위에서 다른 군에 비해 유의하게 낮았다(Kruskal-Wallis test, p < 0.05). 결론: 레진계 근관충전제를 사용 시에는, 자가부식형 전처리제와 이중중합형 sealer보다는, total etch/wet bonding 개념과 적절한 광중합을 도모하는 전처리제 및 접착제의 사용이 치근단 미세누출을 감소시키므로 추천된다.

• 한국정밀공학회지
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• 제33권7호
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• pp.541-549
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• 2016

Rolling contact fatigue and wear on rails are inevitable in railway operations due to excessive wheel-rail contact stress. The wear is influenced by vehicle speed, contact pressure, environmental conditions, and many other factors. Speeding on a curved track causes many problems such as wear on the gauge of the rail and rolling contact fatigue. Managing environmental conditions can reduce problems on the wheel and rail interface. In this study, the wear characteristics of wheel and rail materials were investigated by twin-disc testing using various parameters. The results of the wear test indicated that the wear rate under dry conditions was larger than that under wet conditions. We found that contact fatigue damage occurred on the rail in dry conditions, however, the surface of the specimen under water remained smooth. Also, the friction coefficient in dry conditions was larger than in wet conditions.

• 항공우주기술
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• 제9권2호
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• pp.98-104
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• 2010

대기 중의 수증기는 가스터빈엔진의 주요성능에 많은 영향을 끼친다. 습공기의 영향은 기온 및 기압이 높은 여름철 해면 고도, 높은 비행 마하수 그리고 낮은 엔진 회전수에서 이 더욱 두드러진다. 이러한 습공기 유입에 따른 가스터빈 엔진의 성능변화의 정도를 살펴보고자 가스터빈 시뮬레이션 프로그램(GSP)과 200lbf 급 초소형 터보제트 엔진의 고공환경 성능시험을 통해 습도가 엔진성능에 미치는 영향에 대하여 알아보았다. 고공환경 엔진시험을 통해, 건공기 유입에 비해 습공기 유입 시 순추력에서 2.826% 낮게, 비연료소모율에서 1.325% 높게 측정되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권6호
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• pp.18-31
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• 2013

This study was performed to examine use of the pump-and-treat method for remediation of TCE, CF and CT in groundwater contaminated by DNAPL. The Woosan industrial complex is located in Wonju, about 120 km east of Seoul, Korea. Two pumping wells (KDPW7 and KDPW8) and five monitoring wells (KDMW7, KDMW8, KDMW9, KDMW10, and SKW2) were installed for the test. An asphalt laboratory is a main source of the extensive subsurface contamination at this site. To evaluate change in the concentrations of TCE, CF, and CT in groundwater in the study area, three rounds of pump-and-treat pilot tests were performed (6 July to 6 August, 22 August to 6 September, and 19 September to 2 December in 2011). The groundwater levels and the concentrations of TCE, CF, and CT exhibited negative correlations in the wet season but positive correlations in the dry season, which suggests that the TCE concentrations were mainly controlled by dilution through rainfall during the wet season and by residual TCE, CF, and CT in the unsaturated zone during the dry season. These possibilities should be considered in the full-scale remediation plan.

• 대한토목학회논문집
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• 제33권6호
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• pp.2223-2235
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• 2013

본 연구는 남 북한에서 시 공간적 강수특성 변화를 이해하고자, 남한 65개 기상청 관측소에서 1963년부터 2010년까지, 북한 27개 관측소에서 1973년부터 2010년까지 측정된 일 강수량 자료를 분석했다. 총량(Amount), 극치(Extremes)와 빈도(Frequency)를 나타내는 지표들을 선정하였고, 각각의 지표를 RIA (Rainfall Index for Amount), RIE (Rainfall Index for Extremes), RIF (Rainfall Index for Frequency)로 정의하였다. 남 북한 행정구역별로 2000년까지 평균 지표 값과 2001년부터 2010년까지 최근 10년 평균 지표 값을 비교하였다. 과거에 비해 최근 10년간 남한은 연중 강우일수를 나타내는 NWD (Number of Wet Days)와, 200년 빈도 강수량을 나타내는 Freq200 (200-yr Frequency Rainfall)을 제외한 SDW (Annual mean daily rainfall over wet-days), TotalDR (Annual Total Rainfall Amount), Prcp50 (Annual number of wet days over 50 mm/day), Prcp80 (Annual number of wet days over 80 mm/day), CWD (Annual maximum number of consecutive wet-days), AMDR (Annual maximum daily rainfall), 그리고 R3day (Annual maximum 3-days rainfall total) 값들이 모두 증가한 양상을 보였지만 북한은 SDW와, 연총강우량 TotalDR을 제외하곤 모두 감소하였다. 또한 연평균 지표 값의 경향성을 확인하기 위해 통계적 방법인 Mann-Kendall 검정을 실시하였다. 과거 감소의 경향을 나타내던 각 관측지점이 최근에 이르러서는 경향성의 역전 되는 현상을 보인 곳이 나타났으며, 이는 평균값만을 바탕으로 강수사상 특성변화를 분석하는 방법의 한계점으로 볼 수 있다. 본 연구의 결과는 한반도 물 관리 기후변화에 대한 영향 분석과 대응 대책 마련에 활용될 수 있을 것이다.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.321-338
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• 1996

The purpose of this study was to evaluate the effect of moistening and air-drying of acid conditioned dentin and enamel on the marginal microleakage. In this study, Class V cavity were prepared on both buccal and lingual surface of sixty extracted human premolars with cementum margin. These specimens were randomly devided into three groups and three dentin adhesives(Scotchbond Multi-Purpose, All bond 2, Prisma Universal Bond 3) were applied to each group. The specimens in each group were subdevided into four groups (Wet/primed, Dry/primed, Wet/not primed, Dry/not primed) and the etched dentin and enamel surface were treated these four surface treatments prior to the placement of a bonding agent or adhesive. Wet/primed group was simply blot-dried with a damp facial tissue before primer placement ; Dry/primed group was air dried for 30 seconds before the placement of a primer ; Wet/not primed group and Dry/not primed group were not primed after blot dried and air dried for 30 seconds each group. The bonding agent and composite resin were applied for each group. All specimens were exposed to 500 cycle of thermal stress. Specimens were placed in a silver nitrate solution and then sectioned buccolingually through the center of the restoration. The dye penetrations of the specimens were observed with a stereo microscope. The statistical test were applied to the results using a one way analysis variance (ANOVA) and Duncan's multiple range test. The aspects of silver ion penetration into the resin/dentin interface were examined under scanning electron microscopy. The results were as follows. 1. In all groups, the enamel margin showed significantly lower leakage value than the cementum margin (p<0.05). 2. Regardless of various surface treatment and dentin adhesives, there was no significant difference at the enamel margins (p>0.05). 3. At the dentin margins, the leakage values of Dry/not primed group showed significantly higher than that of the other groups (p<0.05). The leakage values of Wet/primed group showed significantly lower than that of the other groups, but, there was no significant difference between Wet group and Dry group. 4. There was no significantly difference between the dentin adhesives regarding the surface treatments in all groups(p>0.05). 5. On the backscatterd scanning electron microscopy observation, the penetration of the silver ion occured at the bonding resin/dentin interface. In the Wet/primed group, resindentin hybrid zone and resin penetration into the dentin was observed. The resin tags were compactively formed to a thickness of $3\sim4{\mu}m$ at the upper part of dentinal tubules. In the Dry/primed group, the thickness of the hybrid zone and the diameter, depth of the resin tags diminished. In the Non-primed groups, the hybrid zone was not identified and few resin tag was observed. There was the gap formation in the resin/dentin interface.

• Asian Pacific Journal of Cancer Prevention
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• 제17권1호
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• pp.373-376
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• 2016

The Mini Parasep SF fecal parasite concentrator (MPSFC) is a new modification of the closed concentration system, which can easily be adopted in any routine clinical pathology laboratory. Here we describe our experience with the system in diagnosing Opisthorchis viverrini. A total of 199 fecal samples was submitted for routine examination in the clinical pathology laboratory of Suranaree University of Technology hospital, Nakhon Ratchasima province, Thailand, during August to October 2015. Out of all samples examined, 10 (5.03%) were positive with intestinal parasites including O. viverrini (2.01%), followed by Strongyloided stercoralis (1.51%), Hookworm (0.5%), Taenia spp. (0.5%), and Entamoeba coli (0.5%). Regarding the distribution of intestinal parasites in relation to the methods used, and found that 4 samples (2.01%) were positive using the direct wet smear method while 10 (5.03%) were positive with the Mini Parasep SF method; the difference was statistically significant ($X^2$-test = 116.506, p-value =0.001). Mean time for processing using the Parasep system was 6.03 min/sample, the conventional direct wet smear method at 0.3 min/sample. Cost per test, conventional direct wet smear method costing less than the Parasep method at USD 0.74/sample versus USD 1.47/sample. This first report of O. viverrini detection using MPSFC indicates that Parasep concentration test is useful in the routine laboratory, increasing the yield of parasites as compared to direct microscopy, but with greater processing time and cost. Further comparisons between the Parasep concentration test and common methods for O. viverrini detection are required, particularly concerning use in epidemiological surveys.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.665-670
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• 2001

The purpose of this study is to develop a new type dryer, which is to proceed mixing and drying of wet-materials at the same time and drying process is carried out in a closed system. In this drying system, thermal contact occurs, when a fluidized zone is created by paddle mechanism. Accordingly, wet-materials is dried in a short time without any damage. Also wet-materials could be dried uniformly to low moisture contents. It is suitable to dry a small quantity of multi-kind materials. And drying process is carried out in a closed system, so as for environmental pollution dust not to be emitted into the atmosphere. Accordingly, it could be used to dry not only food and chemical materials, but also environmental pollution materials.

• 펄프종이기술
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• 제34권4호
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• pp.1-6
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• 2002

In order to simulate the actual wet-end process in papermachine, RDA, a novel handsheet former, was used and following results were obtained. While the addition of polyelectrolytes gives significant effect on fiber flocculation, increase of stock consistency influenced on the formation of RDA sheets greatly. In particular, the consistency increase from 0.3 % to 0.4% abruptly increased floe size of RDA sheet and it results in severe deterioration of paper strength. Stock consistency, therefore, should be regarded as the most important factor in the formation simulation with RDA and should be controlled as the first sequence of tuning the operating conditions of RDA to simulate correctly the target machine paper's formation.

• Journal of Ship and Ocean Technology
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• 제1권1호
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• pp.26-34
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• 1997

Under water wet welding is an economically alternative for the repair of offshore structures. In this paper investigations on the fatigue strength of a wet welded pipe structural member have been reported. For the connection a special sleeve patch design has been developed. The joint was fatigue tested. The evaluation of the test was carried out by means of the hot-spot approach with regard to several extrapolation rules of the hot-spot stress. Obtained results have been compared to actual classfication rules and recommendations.