• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.196-205
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• 2020

The purpose of this study was to investigate a method for improving the physical and mechanical properties of laminated board made from oil palm trunk (OPT). The effects of pretreating the lamina with heat-pressure and altering the lamina composition of the laminated board were investigated. The outer third of OPT in cross-section had high-density wood, while the underlying third had low to medium density. The hot press was applied to pretreat the lamina that had low to medium density. The lamina were 1.5 cm in thickness, 5 cm in width, and 65 cm in length. The hot press was applied at 2.94 MPa or 4.41 MPa at 150 ℃ for 60 minutes, and the target thickness of the lamina was 1 cm. The three layers of the laminated board samples were bonded with isocyanate adhesive at a glue spread of 300 g/㎡ and cold pressed at 0.98 MPa for 3 h. The laminated board samples were tested according to Japanese Agricultural Standard (JAS) 234-2003. The results showed that the densification of the inner lamina did not significantly affect the physical-mechanical properties of the laminated board produced. However, the laminated board made with high-density laminas for the outer layers fulfilled the JAS 234-2003 standard for the modulus of elasticity and the modulus of rupture.

• Elastomers and Composites
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• 제43권3호
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• pp.147-156
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• 2008

본 연구에서는 실란 커플링제을 변량 배합하여 습식법과 건식법으로 실리카를 전처리하여 epoxy/carboxyl-terminated butadiene acrylonitirile (EP/CTBN) 복합체를 제조하였다. EP/CTBN 복합체의 경화특성 및 표면자유에너지, 인장강도 및 충격강도의 기계적 특성과 계면 특성을 건식법과 습식법에 따라 고찰하였다. Differential scanning calorimetry(DSC)의 결과 실란커플링제의 양이 증가함에 따라 실리카의 기공을 막아 경화제의 양을 증가시켜 경화온도가 감소되었으며, 건식법보다는 습식법이 EP/CTBN 복합체의 경화온도를 감소시킴을 알 수 있었다. 또한 실란커플링제의 양이 증가함 따라 표면자유에너지와 충경강도가 증가되었으나, 인장강도는 실란커플링제의 양이 4 wt%일 때 감소되었으며, 습식법보다는 건식법이 더 물성을 향상시킴을 알 수 있었다.

• 한국결정성장학회지
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• 제23권6호
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• pp.296-301
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• 2013

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under the thermal chemical vapor deposition system. A 304-type stainless steel was used as a substrate with nickel powders as the catalyst. The surface of the substrate was pretreated using a sand paper or a mechanical drill to enhance the production yield of the carbon coils. The characteristics of the deposited carbon nanomaterials on the substrates were investigated according to the surface state on the stainless steel substrate. The protrusion induced by the grooves on the substrate surface could enhance the formation of the carbon nanomaterials having the coils geometries. The cause for the enhancement of the carbon coils formation by the grooves was suggested and discussed with the surface energies for the interaction between as-growing carbon elements. Finally, we could obtain the massive production yield of the carbon coils by the surface pretreatment using SiC sand papers on the several tens grooved stainless steel substrate.

• 신재생에너지
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• 제6권2호
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• pp.27-32
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• 2010

Low Calorific Gas Turbine (LCGT) has been developed as a next generation power system using landfill gas (LFG) and biogas made from various organic wastes, food Waste, waste water and Livestock biogas. Low calorific fuel purification by pretreatment system and carbon dioxide fixation by green house system are very important design target for the optimum applications of LCGT. Main troubles of Low Calorific Gas Turbine system was derived from the impurities such as hydro sulfide, siloxane, water contained in biogas. Even if the quality of the bio fuel is not better than natural gas, LCGT may take low quality gas fuel and environmental friendly power system. The mechanical characterisitics of LCGT system is a high energy efficiency (>70%), wide range of output power (30 kW - 30 MW class) and very clean emission from power system (low NOx). A green house has been designed for four different carbon dioxide concentration from ambient air to 2000 ppm by utilizing the exhaust gas and hot water from LCGT system. LCGT is expected to contribute achieving the target of Renewable Portfolio Standards (RPS).

• 한국작물학회지
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• 제47권1호
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• pp.62-67
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• 2002

An efficient system of rice microspore culture could contribute to the production of genetically modified rice. The microspores were isolated by mechanical or shed methods. The number of microspores per 100 anthers isolated at uninucleate stage was higher than (or similar to) those at binucleate stage in isolation method with pestle or spatular, but microspore divisions were not easily observed on both stages. On the other hand, pollen division in shed pollen culture was observed more frequently at uninuclear than at binuclear stage. Cold pretreatment at 1$0^{\circ}C$ for 10 days resulted in the best multicellular division to produce microcalli at 12.5% efficiency in shed microspores. Heat shock at 33$^{\circ}C$ for one hour before or after pollen shedding enhanced cell division and callus formation. Out of twelve green regenerants, two were haploids and ten were diploids based on the chromosome analysis of root tips. The size of stoma was 12$^{m}$ m in haploids and 15 ${\mu}{\textrm}{m}$ in diploids determined by scanning electron microscope (SEM).

• 상하수도학회지
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• 제22권3호
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• pp.343-350
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• 2008

Many reports have warned of insufficient water supply in most countries in future and prospected providing safe and clean water become more difficult by lack of access to sustainable drinking water resources. Several facts and figures explained the impact by natural climate change and human activity results in the water scarcity and deterioration. Among many scientific solutions, the seawater desalination using a reverse osmosis membrane, so called SWRO (Seawater Reverse Osmosis) process, has been recognized as one of the most promising alternatives because of its stability and efficiency in producing large amount of drinking water from seawater through desalination by membrane filtration. Recently, in Korea, numerous researches are conducted to develop more productive and cost effective SWRO process for its wide implementation. The objective of this paper is to review the patents concerning SWRO technologies involving the plant engineering, maintenance including pretreatment of seawater and fouling control, module design, and mechanical units development for energy saving. The patents in Korea, U.S., Japan, Europe, and PCT were intensively researched and analyzed to provide the state of the art as well as leading edge technology on SWRO. This information can hopefully suggest meaningful guidelines on future research and development.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.293-293
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• 2010

Carbon nanotubes (CNTs) have attracted considerable attention as possible routes to device miniaturization due to their excellent mechanical, thermal, and electronic properties. These properties show great potential for devices such as field emission displays, CNT based transistors, and bio-sensors. The metals such as nickel, cobalt, gold, iron, platinum, and palladium are used as the catalysts for the CNT growth. In this study, diamond-like carbon (DLC) was used for CNT growth as a nonmetallic catalyst layer. DLC films were deposited by a radio frequency (RF) plasma-enhanced chemical vapor deposition (RF-PECVD) method with a mixture of methane and hydrogen gases. CNTs were synthesized by a hot filament plasma-enhanced chemical vapor deposition (HF-PECVD) method with ammonia (NH3) as a pretreatment gas and acetylene (C2H2) as a carbon source gas. The grown CNTs and the pretreated DLC filmswere observed using field emission scanning electron microscopy (FE-SEM) measurement, and the structure of the grown CNTs was analyzed by high resolution transmission scanning electron microscopy (HR-TEM). Also, using energy dispersive spectroscopy (EDS) measurement, we confirmed that only the carbon component remained on the substrate.

• Membrane and Water Treatment
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• 제3권1호
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• pp.35-49
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• 2012

In membrane processes, various agents are used to enhance, protect, and recover membrane performance. Applying these agents in membrane modification could potentially be considered as a simple method to improve membrane performance without additional process. Citric acid (CI) and sodium bisulfite (SB) are two chemicals that are widely used in membrane feed water pretreatment and cleaning processes. In this work, preadsorptions of CI and SB were developed as simple methods for polysulfone ultrafiltration membrane modification. It was found that hydrogen bonding and Van Der Waals attraction could be responsible for the adsorptions of CI and SB onto membranes, respectively. After modification with CI or SB, the membrane surfaces became more hydrophilic. Membrane permeability improved when modified by SB while decreased a little when modified by CI. The modified membranes had an increase in PEG and BSA rejections and better antifouling properties with higher flux recovery ratios during filtration of a complex pharmaceutical wastewater. Moreover, membrane chlorine tolerance was elevated after modification with either agent, as shown by the mechanical property measurements.

• 대한수의학회지
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• 제33권4호
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• pp.617-622
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• 1993

The preliminary studies on the localization of adrenoceptors were performed on smooth muscle strips of bovine esophageal groove. The mechanical activity of the muscle strip was recorded isometrically in vitro.w In the bottom circular muscle strips. the excitatory ${\alpha}-adrenergic$ responses were not blocked by tetrodotoxin$(2.1{\times}10^{-6}M)$ and denervation which was carried by cold storage of strips for 48 hrs in Tyrode's solution at $5-6{^{\circ}C}$ without oxygen supply. These excitatory ${\alpha}-adrenergic$ responses were partially blocked by atropine. In the lip longitudinal muscle strips, the inhibitory${\beta}-adrenergic$ responses were not blocked by pretreatment of tetrodotoxin and atropine. The results suggest that ${\beta}-adrenergic$ receptors mediating relaxations are located on the postsynaptic smooth muscle cells, whereas ${\beta}-adrenergic$ receptors mediating contractions are located both in the smooth muscle cells and in the cholinergic neurones.

• Corrosion Science and Technology
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• 제18권4호
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• pp.148-153
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• 2019

Pure nickel with a thickness of 1 mm was plated on type 304 stainless steels and low alloy steels (JIS G3131 SPHC) by electrolytic plating method in a circulating plating bath. Plating performance, mechanical properties, and surface characteristics were evaluated in terms of pretreatment process, anode material, pH, current density, and flow rate of the plating solution. Addition of hydrochloric acid during pre-treatment process improved the adhesion performance of plating. To improve plating efficiency, it is desirable to use S-nickel rather than electrolytic nickel. The use of S-nickel was also confirmed to be desirable for maintaining the pH and concentration of the plated solution. The defect of the plating using S-nickel anode produced pit on the surface. However, it is believed that proper control can be obtained by increasing the flow rate. Internal stress and hardness values of electrolytic nickel plating according to current density need to be carried out with further studies.