• 한국전산유체공학회지
• /
• 제20권1호
• /
• pp.16-25
• /
• 2015

The present study investigates the sloshing phenomena in a two-dimensional rectangular tank at a low filling level by using a level set method based on finite volume method. The code validations are performed by comparing between the present results and previous numerical and experimental results, which gives a good agreement. Various excitation frequencies and excitation amplitude of the 30% filling height tank have been considered in order to observe the dependence of the sloshing behavior on the excitation frequency and amplitude. Regardless of excitation amplitude, the maximum value of wall pressure occurs when the excitation frequency reaches the natural frequency. The time sequence of free surface and corresponding streamlines for excitation frequencies have been presented to analysis the variation of wall pressure according to time, which contributes to explain the double peaks in the time variation of wall pressure.

• Restorative Dentistry and Endodontics
• /
• 제25권2호
• /
• pp.202-211
• /
• 2000

The aim of this study was to compare the apical sealing ability of a new thermoplasticized gutta-percha filling technique, the Easy Filling and the Quick Obturation system with lateral condensation technique and Thermafil system to evaluate their clinical acceptabilities. Fifty-two extracted single-rooted teeth were instrumented to #35 using the .04 taper ProFile system. Four groups of 12 teeth were obturated by lateral condensation technique. Thermafil system and two new thermoplasticized gutta-percha techniques, the Easy Filling system and Quick Obturation system (Meta Dental co. Ltd. Korea), respectively. Four teeth served as controls. After the teeth were immersed in 2% methylene blue dye for 48 hours, they were resected horizontally at 1mm to 5mm level from the anatomical apex using a low-speed microtome. Each section was examined under a stereomicroscope at ${\times40}$ magnification and photographed. After each image was scanned, the leakage area was measured at each level using Brain 3 (Nosdia Tech., Korea) software. Leakage ratio was calculated for each group and was analyzed statistically to come up with the following results: 1. At 1mm level, the Quick Obturation system had the largest amount of apical leakage and it was statistically significant when compared with the lateral condensation group and the Thermafil group (p<0.05). 2. At 2mm and 3mm level, there were no significant difference of apical leakage among all four groups (p>0.05), and from 4mm level, no apical dye penetration was observed in all the groups. In conclusion, the apical seal produced by Easy Filling system and the Quick Obturation system was comparable to lateral condensation technique and Thermafil system except for the 1mm level. More improvement of the apical seal can be expected as the operator becomes skillful with the new techniques.

• 한국연초학회지
• /
• 제22권2호
• /
• pp.164-169
• /
• 2000

The reconstituted tobacco leaves(RTL) playa major part in the control of the low density and tar cigarette. Reconstituted tobacco manufactured by the papermaking process has much higher filling power than homogenized tobacco manufactured by slurry and rolling process. Fragile reconstituted tobaccos are liable to lead to small particles detrimental for filling power so they must be properly flexible. This work was conducted to determine the effect of CaCO$_3$ addition in paper-making process on the filling power and the flexibility of the reconstituted tobacco and to obtain the fundamental informations for improving the quality of domestic reconstituted tobacco. We analyzed the wood fiber species, the filler level, the fiber length, the fineness level and observed the surface of the RTL. From the obtained results, we could determine that foreign reconstituted tobacco was manufactured by blending softwood with hardwood and over 8% of calcium carbonate at the addition level. The domestic RTL has much higher fine fiber level by 23.2 % than that of foreign, so the refining treatment process and the condition must be reoptimized for the improvement of RTL quality.

• 한국전자통신학회논문지
• /
• 제15권3호
• /
• pp.553-562
• /
• 2020

S 밴드, C 밴드 그리고 X 밴드 레이더는 기상 관측을 목적으로 사용되고 있다. 기상청, 환경부, 공군은 부처별 관측 목적에 따라 레이더를 운용하고 있기 때문에 설치 지점과 관측 특성이 서로 다르다. 기상 관측 관점에서는 지리산과 태백산 인근의 산악 지형을 따라 고도 1 km 이하의 저층 관측의 한계 지역이 나타난다. 소형 레이더 설치를 가정하여 저층 관측 보완을 모의하였다. 또한, 북한 지역의 위험 기상 감시를 위해 북한의 강수를 분석하고 대형 레이더 관측망을 모의하였다. 종합하여 한반도 레이더 관측망 구축안을 제시하였다.

• 터널과지하공간
• /
• 제15권5호
• /
• pp.359-368
• /
• 2005

NATM 터널을 굴착하기에 토피가 너무 낮은 경우에는 보통 개착터널공법이 적용된다. 그러나 토피가 매우 낮거나 없는 계곡부에서 개착터널을 시공하기 위해서는 추가적인 두 곳의 갱구 형성과 복토가 이루어질 때까지 임시 사면에 대한 유지관리가 필요하다. 이런 경우에는 복토를 통해 토피를 확보한 후 터널을 굴착하는 방안이 유효하다. 이 연구는 터널 굴착이전에 소일시멘트로 복토한 후 굴착작업이 이루어진 대만고속철도 C240현장에 대한 사례 연구이다. 소일시멘트의 포틀랜드 시멘트 함유량은 $2\~4\%$이고, 1회 복토층의 두께는 $130\~250\;mm$ 범위가 되도록 시공하였다. 터널 굴착에 따른 소일시멘트 사면 및 터널내 최종 구조물인 콘크리트 라이닝에 대한 수치해석을 통해 안정성을 평가하였다.

• 한국석유지질학회:학술대회논문집
• /
• 한국석유지질학회 2000년도 제7차 학술발표회 발표논문집
• /
• pp.14-30
• /
• 2000

Hierarchically controlled sequence stratigraphic analysis shows that the Lower Ordovician mixed carbonate-siliciclastic Mungok Formation, Korea consists of three depositional sequences: T1, T2, and T3. Sequence boundaries are generally marked by abrupt transition from coarse-grained shallow-water carbonates to fine-grained deeper-water carbonates mixed with fine-grained siliciclastics, and show indication of subaerial exposure such as karstification. Within this sequence stratigraphic framework, facies characteristics indicate that the Mungok sequences were mostly deposited in subtidal ramp environments. High-frequency cycles consist of upward-shallowing facies successions. Cycles of shallow-water and basinal deposits are not represented well, probably due to cycle amalgamation. Cycle stacking patterns do not show a consistent thickness change that reflects a large-scale sea-level change due to unfilled accommodation space. The Mungok sequences show that many factors including relative sea-level change and topography are involved in controlling sequence development on carbonate ramps. The depositional setting evolved from the high-energy ramps in the sequences T1 and T2 into the low-energy ramp in the sequence T3. Topography is interpreted to have been responsible for the different energy regimes of the carbonate ramps in the Mungok sequences. The high ramp gradient in the sequences T1 and T2 seems to be caused by space-time-dissociated differential sedimentation resulting in spatially narrow distribution of sediment filling, which in turn may be related to high rate of relative sea-level change. In contrast, low ramp gradient was maintained in the sequence T3 during slow changes of relative sea level resulting in broad distribution of sediment filling.

• Restorative Dentistry and Endodontics
• /
• 제46권1호
• /
• pp.2.1-2.8
• /
• 2021

Objectives: New premixed bioceramic root repair materials require moisture for setting. Using micro-computed tomography (micro-CT), this study evaluated the filling ability and volumetric changes of calcium silicate-based repair materials (mineral trioxide aggregate repair high-plasticity [MTA HP] and Bio-C Repair, Angelus), in comparison with a zinc oxide and eugenol-based material (intermediate restorative material [IRM]; Dentsply DeTrey). Materials and Methods: Gypsum models with cavities 3 mm deep and 1 mm in diameter were manufactured and scanned using micro-CT (SkyScan 1272. Bruker). The cavities were filled with the cements and scanned again to evaluate their filling capacity. Another scan was performed after immersing the samples in distilled water for 7 days to assess the volumetric changes of the cements. The statistical significance of differences in the data was evaluated using analysis of variance and the Tukey test with a 5% significance level. Results: Bio-C Repair had a greater filling ability than MTA HP (p < 0.05). IRM was similar to Bio-C and MTA HP (p > 0.05). MTA HP presented the largest volumetric change (p < 0.05), showing more volume loss than Bio-C and IRM, which were similar (p > 0.05). Conclusions: Bio-C Repair is a new endodontic material with excellent filling capacity and low volumetric change. The gypsum model proposed for evaluating filling ability and volumetric changes by micro-CT had appropriate and reproducible results. This model may enhance the physicochemical evaluation of premixed bioceramic materials, which need moisture for setting.

• 한국초전도ㆍ저온공학회논문지
• /
• 제16권4호
• /
• pp.71-77
• /
• 2014

For a long-term space mission, filling process of cryogenic liquid propellant is operated on a space vehicle in space. A vent process during transfer and filling of cryogenic propellant is needed to maintain the fuel tank pressure at a safe level due to its volatile characteristic. It is possible that both liquid and vapor phases of the cryogenic propellant are released simultaneously to outer space when the vent process occurs under low gravity environment. As a result, the existing filling process with venting not only accompanies wasting liquid propellant, but also consumes extra fuel to compensate for the unexpected momentum originated from the vent process. No-Vent Fill (NVF) method, a filling procedure without a venting process of cryogenic liquid propellant, is an attractive technology to perform a long-term space mission. In this paper, the preliminary experimental results of the NVF process are described. The experimental set-up consists of a 9-liter cryogenic liquid receiver tank and a supply tank. Liquid nitrogen ($LN_2$) is used to simulate the behavior of cryogenic propellant. The whole situation in the receiver tank during NVF is monitored. The major experimental parameter in the experiment is the mass flow rate of the liquid nitrogen. The experimental results demonstrate that as the mass flow rate is increased, NVF process is conducted successfully. The quality and the inlet temperature of the injected $LN_2$ are affected by the mass flow rate. These parameters determine success of NVF.

• 현장농수산연구지
• /
• 제20권1호
• /
• pp.175-185
• /
• 2018

개체군생장율(CGR)은 유수형성기와 출수기 사이에 가장 높았는데, 주남벼, 낙동벼, 소비벼 등이 높았으며, 이삭의 등숙속도는 시비량이 증가할수록 증가하였고, 출수 후 20일까지 가장 많이 증가하고, 그 이후에는 점차 감소하는 경향이었는데, 주남벼, 소비벼에서 빨랐다. 관행재배에서 수량이 높은 품종은 소비재배에서도 수량이 높았으며, 소비재배시 수량에 가장 많은 영향을 미치는 수량구성요소는 단위면적당 영화수로, 고도의 정의 상관관계를 나타냈다. 또한 백미품위는 시비량이 증가할수록 감소하였는데, 소비벼의 품위가 가장 낮았으며, 사미와 분상 질립의 증가가 원인이었다.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2003년도 International Symposium
• /
• pp.261-278
• /
• 2003

Concepts.Wafer-Level Chip-Scale Concept with Handling Substrate.Low Accuracy Placement Layout with Isolation Trench.Possible Pitch of Interconnections down to $10{\mu}{\textrm}{m}$ (Sn-Grains).Wafer-to-Wafer Equipment Adjustment Accuracy meets this Request of Alignment Accuracy (+/-1.5 ${\mu}{\textrm}{m}$).Adjustment Accuracy of High-Speed Chip-to-Wafer Placement Equipment starts to meet this request.Face-to-Face Modular / SLID with Flipped Device Orientation.interchip Via / SLID with Non-Flipped Orientation SLID Technology Features.Demonstration with Copper / Tin-Alloy (SLID) and W-InterChip Vias (ICV).Combination of reliable processes for advanced concept - Filling of vias with W as standard wafer process sequence.No plug filling on stack level necessary.Simultanious formation of electrical and mechanical connection.No need for underfiller: large area contacts replace underfiller.Cu / Sn SLID layers $\leq$ $10{\mu}{\textrm}{m}$ in total are possible Electrical Results.Measurements of Three Layer Stacks on Daisy Chains with 240 Elements.2.5 Ohms per Chain Element.Contribution of Soldering Metal only in the Range of Milliohms.Soldering Contact Resistance ($0.43\Omega$) dominated by Contact Resistance of Barrier and Seed Layer.Tungsten Pin Contribution in the Range of 1 Ohm