• Journal of Korean Dental Science
• /
• v.5 no.1
• /
• pp.21-28
• /
• 2012

Purpose: In this study the bone healing ability of autogenous tooth bone graft material as a substitute material was evaluated in a mini-pig cranial defect model through histologic examinations and osteonectin reverse transcription polymerase chain reaction (RT-PCR) quantitative analysis. Materials and Methods: A defect was generated in the cranium of mini-pigs and those without a defect were used as controls. In the experimental group, teeth extracted from the mini-pig were manufactured into autogenous tooth bone graft material and grafted to the defect. The mini-pigs were sacrificed at 4, 8, and 12 weeks to histologically evaluate bone healing ability and observe the osteonectin gene expression pattern with RT-PCR. Result: At 4 weeks, the inside of the bur hole showed fibrosis and there was no sign of bone formation in the control group. On the other hand, bone formation surrounding the tooth powder granule was observed at 4 weeks in the experimental group where the bur hole was filled with tooth powder. Osteonectin gene expression; there was nearly no osteonectin expression in the control group while active osteonectin expression was observed from 4 to 12 weeks in the experimental group. Conclusion: We believe this material will show better results when applied in a clinical setting.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.7
• /
• pp.1-12
• /
• 2014

This paper is proposed to design the new heat-sink apparatus for improving the heat transfer characteristics in the power LED chip, and results of the operation characteristics were discussed. The core design is that the soldering through-hole on the FR-4 PCB board is formed to the effective heat transfer. That is directly filled with Ag-nano materials, which shows the high thermal conductivity. The heat transfer medium consisting of Ag-nano materials is classified into two structures. Mediums are called as the heat slug and the multi-pin in this work. The heat of the high temperature generated from the LED chip was directly transferred to the heat slug of the one large size. And the accumulated heat from the heat slug was quickly dissipated by the medium of the multi-pin, which is the same body with the heat slug. This multi-pin was designed for the multi-dissipation of heat by increasing the surface areas with a little pins. Subsequently, the speed of the heat transfer with this new heat-sink apparatus is three times faster than the conventional heat-sink. Therefore, the efficiency of the illuminating light will be improved by adapting this new heat-sink apparatus in the large area's LED.

• Structural Engineering and Mechanics
• /
• v.89 no.5
• /
• pp.479-489
• /
• 2024

The cracking mechanism in ceramsite aerated concrete block (CACB) infill walls were studied in low seismic fortification intensity coastal areas with frequent occurrence of typhoons. The inter-story drifts of an eight-story residential building under wind loads and a seismic fortification intensity of six degrees were analyzed by using the PKPM software. The maximum inter-story drift ratio of the structure in wind load was found to be comparable to that under the seismic fortification intensity of six degrees. However, when accounting for the large gust wind speed of typhoon, the maximum inter-story drift ratio was much larger than that obtained under reference wind load. In addition, the finite element models of RC frames were employed by displacement loading to simulate two scenarios with and without window hole in the CACB infill walls, respectively. The simulation results show no signs of cracking in both the infill walls with window hole and those without window for the inter-story drift caused by seismic loads and the reference wind load. However, both types of infill walls experienced structural creaking when assessing the gust wind pressure recorded from previous typhoon monitoring. It is concluded that an underestimate of wind loads may contribute substantially to the cracking of frame CACB infill walls in low seismic fortification intensity coastal areas. Consequently, it is imperative to adopt wind pressure values derived from gust wind speeds in the design of CACB infill walls within frame structures. Finally, the future research directions of avoiding cracks in CACB filled walls were proposed. They were the material performance improving and building structure optimizing.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.545-552
• /
• 2003

For temporary excavation support in a congested urban area, the strand of ground anchor should be removed to get permission of the private land to install anchors. But the strand doesn't need to be removed in the outside city area after use. So the anchor body, tension anchor, is fabricated in-situ. The unbonded length of This anchor has several strands, which wrap only one sheath. When the anchor body is carried into job-site or installed in the bore hole, the sheath is torn easily because it is a very week material. So the grout permeate into the torn sheath. Because of that, the load doesn't transfer to the bond length of ground anchors. It may indicate that load is being transferred along the unbonded length and thus within the potential slip surface assumed for overall stability of the anchored system. The load tests were performed on seven low-pressure grouted anchors installed in weathered soil to verify its problems. Four anchors(Type A) have the unbonded length, which consist of five strands and a week sheath and three anchors(Type B) have strands, which is covered by plastic sheath filled with grease, in the unbonded length. Both anchors are compared with load tests results.

• The Journal of the Acoustical Society of Korea
• /
• v.7 no.4
• /
• pp.117-126
• /
• 1988

The pressure waves scattered by an infinite cylindrical cavity filled with air in a h0mogeneous medium have been calculated for the incident plane pressure waves. For ka = 1/2, 1, 2, 4, 10 and 20, the scattered pressure waves are plotted., where k is the wave number and a is the radius of the cylindrical hole. As an indicator of the directivity of the scattering pattern, we have defined the angle at which the magnitude of the scattered pressure wave decreases by a half(6 dB) with respect to that of the forward peak scattered pressure wave. This angle depends strongly on the values of ka and the distance r, and the angle can be used for the detection of the location and the size of the cavity in a homogeneous medium.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.444-447
• /
• 2008

A nuclear fuel test loop (after below, FTL) is installed in IR1 of an irradiation hole in HANARO for testing neutron irradiation characteristics and thermo hydraulic characteristics of a fuel loaded in a light water power reactor (PWR) or a heavy water power reactor (CANDU). There is an in-pile section (IPS) and an out-pile section (OPS) in this test loop. When HANARO is normally operated, the fuel loaded in the IPS has a nuclear reaction heat generated by a neutron irradiation. To remove the generated heat and to maintain an operation condition of the test fuel, a main cooling water system (MCWS) is installed in the OPS of the FTL. The pump can not continuously suck a fluid and not pressurize the fluid during a cold function test. To verify the flow characteristics of the MCWS, a flow net work analysis has been conducted. When the higher elevation pipelines wholly filled with coolant, it was confirmed through the analysis results that the pump pressurized the coolant normally. And the analysis results described the system characteristics with operation temperature and pressure variation satisfactorily.

• Korean Journal of Materials Research
• /
• v.9 no.2
• /
• pp.124-131
• /
• 1999

Copper film, which is expected to be used as interconnection material for 1 giga DRAM integrated circuits was deposited on hole and trench patterns by Metal Organic Chemical Vapor Deposition(MOCVD) method. After a reflow process, contact and L/S patterns were filled by copper and the characteristics of the Cu reflow process were investigated. When deposited Cu films were reflowed, grain growth and agglomeration of Cu have occurred in surfaces and inner parts of patterns as well as complete filling in patterns. Also Cu thin oxide layers were formed on the surface of Cu films reflowed in $O_2$ambient. Agglomeration and oxidation of Cu had bad influence on the electrical properties of Cu films especially, therefore, their removal and prevention were studied simultaneously. As a pattern size is decreased, preferential reflow takes place inside the patterns and this makes advantages in filling patterns of deep submicron size completely. With Cu reflow process, we could fill the patterns with the size of deep sub-micron and it is expected that Cu reflow process could meet the conditions of excellent interconnection for 1 giga DRAM device when it is combined with Cu MOCVD and CMP process.

• Macromolecular Research
• /
• v.12 no.5
• /
• pp.443-450
• /
• 2004

We have studied the effects that inorganic zeolite powder have on structurally different copolymer [poly(propylene-co-ethylene)] and terpolymer [poly(propylene-co-ethylene-co-l-butene)] systems and the possibility of preparing suitable porous composite films. The impact strength and yield stress of the composites did not improve upon any further loading of zeolite, but the modulus increased gradually with respect to the filler loading. The experimental modulus of each of the two systems was compared with theoretical models. We performed a morphological study of the filler mixing efficiency and image analysis. The number-, weight-, and z-average air hole diameters were compared with respect to the draw ratio as well as the zeolite loading. The experimental results suggest that these two matrices can provide a new choice for preparing future multiphase polymeric porous films by stretching them unidirectionally. In particular, we suggest that a 40 wt% zeolite loading at a draw ratio of 4 is useful for porous film applications.

• Journal of Magnetics
• /
• v.16 no.2
• /
• pp.181-185
• /
• 2011

To improve trapped field characteristics of a high temperature superconducting (HTS) bulk, a technique to implement artificial holes has been studied. The artificial holes, filled up with epoxy or metal, may provide better cooling channel and enhance mechanical strength of the HTS bulk. Although many useful researches based on experiments have been reported, a numerical approach is still limited because of several reasons that include: 1) highly non-linear electromagnetic properties of HTS; and 2) difficulty in modeling of randomly scattered "small" artificial holes. In this paper, a 2-D finite element method with iteration is adopted to analyze trapped field characteristics of HTS bulk with artificial holes. The validity of the calculation is verified by comparison between measurement and calculation of a trapped field in a $40{\times}40\;mm$ square and 3.1 mm thick HTS bulk having 16 artificial holes with diameter of 0.7 mm. The effects of sizes and array patterns of artificial holes on distribution of trapped field within HTS bulk are numerically investigated using suggested method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2015.07a
• /
• pp.122-124
• /
• 2015

This paper provides the design and implementation of Free Viewpoint TV System with multiple Microsoft Kinects. It generates a virtual view between two views by manipulating texture and depth image captured by Kinects in real-time. In order to avoid this, we propose the hole-filling scheme using Nearest neighbor and inpainting. As a result, holes generated by interference are filled with new depth values calculated by their neighbors. However, the depth values are not accurate, but are similar with their neighbors. And depending on the frequency of running a Nearest Neighbor method, we can see that edge's border would be shifted inner or outer of the object.