• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.164-165
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• 2022

In order to solve problems such as acceleration of resource use and environmental pollution, experiments were conducted with the aim of producing indoor finishing materials that can adsorb fine dust and carbon dioxide using gelite and polymer, which are porous materials. Based on the previous experiment, gelite was substituted at each level in a matrix having a polymer S738P substitution rate of 12.5%, and the results are as follows. As the substitution rate of gelite increased, the amount of fine dust and carbon dioxide adsorption increased, which is believed to be due to physical adsorption due to the high porosity of gelite. However, further experiments are needed as the overall adsorption amount is not high due to the filling inside the matrix due to the polymer.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.720-725
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• 2013

When highly shrinkable materials such as coir dust are major component of root media, the degrees of compaction during container filling of root media severely influences the physical properties of root media. It results in the changes in total porosity (TP), container capacity (CC) and air-filled porosity (AFP). This research was conducted to secure the fundamental information in changes of soil physical properties as influenced by the compaction of root media during container filling. To achieve this, three root media were formulated by blending coir dust (CD) with expanded rice hull (CD + ERH, 8:2, v/v), carbonized rice hull (CD + CRH, 6:4) and ground and raw pine bark (CD + GRPB, 8:2). Based on the optimum bulk density, the amount of root media filled into 6.0, 7.5, 8.5, 10.5 and 12.5 cm were adjusted to 90, 100, 110, 120 and 130% based on the weight of root media. Then the changes in TP, CC, and AFP were measured. Elevation of the packing amount of root media in all sizes of pot resulted in the decrease of TP. But the decrease was more severe in CD + ERH and CD + CRH than those in CD + GRPB. The CC also decreased gradually as the packing amounts were elevated in three root media, but the decreases were severe as the container sizes became larger. The AFP decreased drastically by the elevation of the packing amount of root media in all sizes of pot. The AFP was the highest in CD + CRH medium when pot sizes were smaller than 7 cm, but that was the highest in CD + ERH when the pot sizes were larger than 8.5 cm among the 3 root media tested. In this research, the elevation of packing amount of three root media influenced more severely the AFP rather than CC. This result indicates that the packing amount should be controlled to maintain appropriate level of AFP because AFP rather than CC influence severely crop growth. The results obtained through this study can be used to predict the changes in physical properties of root media as influenced by packing amount in various sizes of pots.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.513-520
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• 1999

20 million tons of coal ash has been produced in Korea annually. This causes the environmental problems and the cost of land for ash pond. However the amount of coal ash for recycling is small because of the low level of recycling technology and the ignorance. As the coal ash has the significant engineering properties, it can be utilized as soft ground stabilizer, backfill materials and so forth. The purpose of this paper is to summarize some of the recycling methods of coal ash. One is structural backfill materials, the other is flowable fill. Optimal mixture ratio(fly ash : bottom ash) is determined for structural backfill materials and the model test is performed. The model test accompanied with physical tests were executed for identifying that the flowable fly ash can be used as fill materials such as trench back filling.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.485-493
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• 2020

Numerical analyses were performed using a one-dimensional Euler equation and Godunov Harten-Lax-Van Leer(HLL) Riemann solver in order to study the deceleration characteristics of a 155 mm projectile in a soft recovery system. The soft recovery system consisting of a series of pressure tubes is a system that decelerates the test projectile fired at supersonic speed using a high-pressure gas and filled water inside. Therefore, depending on the gas pressure and the amount of water filling, the deceleration and the exit velocity of the test projectile inside the pressure tube are determined. In this paper, the deceleration characteristics of the test projectile were analyzed according to the gas pressure and water mass filled.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.331-336
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• 2001

Theoretical approach was taken to the whole CNG refueling process. In particular, this study was focused on the prediction of flow rate at any given piping configuration of CNG system, in order that a simulation program for the CNG refueling system should be developed. The simulation result of refueling process was compared with experimental result obtained from various kinds of fueling configuration. The simulation results showed a satisfactory agreement within 10% errors in fueling time, fueling amount, and residual pressure. The developed program would be used a good engineering tools for estimating fueling performance for a any given CNG station.

• Journal of The Korean Astronomical Society
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• v.25 no.1
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• pp.47-64
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• 1992

Cores of globular clusters are an ideal place for close encounters between stars. The outcome of tidal capture can be stellar mergers, close binaries between normal stars (W UMa type), cataclysmic variables composed of white dwarf and normal star pairs, or low-mass X-ray binaries consisting of a neutron star and a normal star pairs. Stellar mergers can be the origin of blue stragglers in dense globular clusters although they are hard to observe. Low mass X-ray binaries would eventually become binary pulsars with short pulse periods after the neutron stars accrete sufficient amount of matter from the companion. However, large number of recently discovered, isolated millisecond pulsars (as opposed to binary pulsars) in globular clusters may imply that they do not have to gain angular speeds during the X-ray binary phase. We propose that these isolated millisecond pulsars may have formed through the disruptive encounters, which lead to the formation of accretion disk without Roche lobe filling companion, between a neutron star and a main-sequence star. Based on recently developed multicomponent models for the dynamical evolution of globular clusters, we compute the expected numbers of various systems formed by tidal capture as a function of time.

• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.928-934
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• 2000

This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.603-607
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• 2002

Recently, the need leer transporting and manipulating minute amount of fluids in microscale channels (so-called micro-fluidics) has been increasing, especially in biotechnology and biochemical processing. This work demonstrates that the mechano-chemical process which consists of mechanical abrasive action combined with chemical process can be used to fabricate micro-fluidic channels more rapidly and cost effectively than other methods. In this work, capillary filling of fluids in micro-channels was investigated by theoretical approaches and experiments. From the experimental results, it is expected that a complex micro-fluidic system can be fabricated using the micro- fabrication technique and microsystem packaging method described in this work.

• Journal of Chest Surgery
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• v.12 no.1
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• pp.61-66
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• 1979

This is a report of a case of tuberculous esophageal perforation, which was surgically treated.. The patient was 32-year-old Korean female patient, who complained swallowing difficulty for` 4 weeks duration. Esophagogram was shown irregular filling defects in the upper one third of esophagus, about 4 cm in length. It was noticed that a small amount of contrast media was leaked out from the involved area of esophagus into the right mediastinum. It was highly suggested that abscess formation was due to perforation of esophageal cancer. Esophagoscopy revealed no definitive evidence of perforation of esophagus, but punch biopsy specimen of esophageal mucosa was shown acute and chronic inflammatory changes. Operation was performed under impression of esophageal cancer. In the right-sided upper mediastinum, a walnut-sized abscess cavity which was connected with esophagus through a fistulous tract was noted. A portion of cavity submitted for frozen section was shown tuberculous inflammation. The abscess cavity, fistula tract, and involved esophageal wall were removed. The perforated esophagus was closed layer by layer. The tuberculous changes were confirmed by histopathologic examination postoperatively. The postoperative course was uneventful.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.97-101
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• 2002

Recently, the need for transporting and manipulating minute amount of fluids in microscale channels (so-called micro-fluidics) has been increasing, especially in biotechnology and biochemical processing. This work demonstrates that the so-called mechano-chemical process which consists of mechanical abrasive action combined with chemical process can be used to f뮤ricate micro-fluidic channels more rapidly and cost effectively than other methods. In this work, capillary filling of fluids in micro-channels was investigated by theoretical approaches and experiments. From the experimental results, it is expected that a complex micro-fluidic system can be fabricated using the micro-fabrication technique and microsystem packaging method described in this work.