• YAKHAK HOEJI
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• v.21 no.4
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• pp.200-210
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• 1977

This investigation was undertaken from February 1976 to September 1976. The detergents in municipal sewages from the Chung Kae Stream, Ahn Yang Stream, and Bong Won Stream were determined at 1.5ppm, 0.93ppm, and 3.36ppm in average respectively. The concentrations of detergents determined in the Han river were 0.013ppm of Kwang Na Ru, 0.11ppm of Duk Do, 0.370ppm of Bo Kwang Dong, and 0.285ppm of Ka Yang Dong basin respectively. And the potable waters of Sung Book Ku and Sung Dong Ku from Ku Eu water pumping station located up-stream of the Han river were less polluted at 0.045ppm and 0.037ppm in average. Young Deung Po Ku and Su Dae Moon Ku had been relatively polluted at 0.181ppm and 0.133ppm. The coagulant, alum [$Al_{2}(SO_{4})_{3}$] could eliminated the small amount of detergent by coagulation. The eliminated rates were about 13% by 5ppm and 22.7% by 20ppm of aluminum sulfate in sewage contained 10ppm of turbidity. The sand and the charcoal adsorbed some detergent as the following Langmuir's equations: For the charcoal, m/x=0.029.$\times$1/Ce-11.43 For the charcoal, m/x=2.705log1/Ce-5.46 Where m: amount of snad and active carbon used(g) x: amount of detergent adsorbed from liquid(g) Ce:concentration in the liquid at equilibrium(miles) The adsorption effect of sand would be neglected. In the low concentration of detergent solution, one gram of active carbon adsorbed 0.263g of detergent. It was determined that one gram of chlorine reduced 5.5g pf DBS om keeping up 0.2ppm of residual chlorine by disinfection process with chlorine compound.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.287-292
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• 1997

This study was tried to form the silica waveguide using high density plasma. Plasma characteristics have been investigated as a function of etch parameters using a single Langmuir probe and optical emission spectroscopy(OES). As etch parameters, $CF_4/CHF_3$ ratio, bias power, and source power were chosen as main variables. The oxide etch characteristics of inductively coupled plasma(ICP) dry etcher such as the etch rate, etch profile, and surface roughness were investigated s a function of etch parameters. On the basis of these results, the core pattern of the wave guide composed of $SiO_2-P_2O_5$ was formed. It was confirmed that the etch rate of $SiO_2-P_2O_5$ core layer was 380 nm/min and the aluminum selectivity to oxide, that is, mask layer was approximately 30:1. The SEM images showed vertical etched profiles and minimal loss of pattern width.

• Journal of the Korean Institute of Gas
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• v.15 no.1
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• pp.30-34
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• 2011

This paper presents a strength safety evaluation of composite pressure container for hydrogen fuel tanks with a storage capacity of 104 liter and 70MPa pressure. The carbon fiber composite container is manufactured by an aluminum liner of Al6061-T6 and composite multi-layers of hoop winding layer in circumferential direction, $12^{\circ}C$ inclined winding layer and $70^{\circ}C$winding layer in helical direction respectively. The FEM results on the strength safety of composite fuel tanks were evaluated with a criterion of design safety of US DOT-CFFC and KS B ISO 11119-2 codes. The FEM computed results indicate that the proposed design model of 104 liter composite container is safe based on two strength safety codes. But, the computed results of carbon fiber fuel tanks based on US DOT-CFFC code is safer compared with that of KS B ISO 11119-2. Thus the hydrogen gas pressure container of 70MPa may be evaluated and designed by US DOT-CFFC code for more strength safety.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.602-608
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• 2005

We have studied to obtain the SAW filter for the Single Phase Unidirectional Transduce. (SPUDT), was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we performed computer-simulated by simulator. We can fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulations. Also, we have performed to obtain the properly conditions about impedance matching of the SAW filter for SPUDT. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are 5000A and $3.6{\mu}m$, respectively. And the width of IDT' fingers is $2.4{\mu}m$, and the space between IDT' finger and reflector is $2.0{\mu}m$. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7.7MHz after when we have matched impedance. Also, we could obtain that ripple characteristics is less than 0.4dB and standing wave ratio is probably 1.5 after when we have matched impedance.

• Journal of Korea Foundry Society
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• v.36 no.6
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• pp.202-207
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• 2016

The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the ${\alpha}$ phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nominal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of $703-781N/mm^2$, elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.719-741
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• 1997

This study was undertaken to compare by Atomic Force Microscope the effects of various finishing and polishing instruments on surface roughness of filling and veneering composite resins. Seven composite resins were studied : Silux Plus (3M Dental Products, U.S.A.), Charisma (Heraeus Kulzer, Germany), Prisma THP (L.D.Caulk, Dentsply, U.S.A.), Photoclearfil (Kuraray, Japan), Cesead (Kuraray, Japan), Thermoresin LC (GC, Japan), Artglass (Heraeus Kulzer, Germany). Samples were placed and polymerized in holes (2mm thick and 8.5mm in diameter) machined in Teflon mold under glass plate, ensuring excess of material and moulded to shape with polyester matrix strip. Except control group (Polyester matrix strip), all experimental groups were finished and polishied under manufacturer's instructions. The finishing and polishing procedure were : carbide bur (E.T carbide set 4159, Komet, Germany), diamond bur (composite resin polishing bur set, GC, Japan), aluminum-oxide disc (Sof-Lex Pop-On, 3M Dental Products, U.S.A.), diamond-particle disc (Dia-Finish, Renfert Germany), white stone bur & rubber point( composite finishing kit, EDENTA, Swiss), respectively. Each specimens were evaluated for the surface roughness with Atomic Force Microscope (AutoProbe CP, Park Scientific Instruments, U.S.A.) under contact mode and constant height mode. The results as follows : 1. Except Thermoresin LC, all experimental composite resin groups showed more rougher than control group after finishing and polishing(p<0.1). 2. A surface as smooth as control group was obtained by $Al_{2}O_{3}$ disc all filling composite resin groups except Charisma and all veneering composite resin groups except Thermoresin LC(p<0.05). 3. In case of Thermoresin LC, there were no statistically significant differences before and after finishing and polishing(p>0.1). 4. Carbide bur, diamond bur showed rough surfaces in all composite resin groups, so these were inappropriate for the final polishing instruments.

• The Journal of Korean Physical Therapy
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• v.14 no.3
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• pp.226-237
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• 2002

This study was performed to investigate the effect of low power laser irradiation on epidermal growth factor(EGF) expression in the burned skin of the rats. Burns of about 3cm in diameter were created with 75'c water on the back of the rats, and the lesion of experimental group were irradiated on days 1, 2, and 3 postwounding. Control tensions were not irradiated. After burns, low power laser irradiation was applied by using 1000Hz, 830nm GaAlAs (Gallium-aluminum- arsenide) semiconductor diode laser. The expression of epidermal growth factor evaluated immunohistochemistry on mouse anti-EGF. The results of this study were as follows 1. In expression of EGF, the lesion of experimental group made EGF to more induce significantly than control tensions. 2. EGF immunoreactivity in burned skin were increased markedly 3 days after burns, and increased gradually from 1 day to 2 days in burns which is laser irradiation These data suggest that low power laser have wound healing effect in the burned skin of the rats.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.4
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• pp.425-431
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• 2016

The usage of Friction Stir Welding(FSW) technology has been increasing in order to reduce the weight in automobile industries. Previous studies that investigated on the FSW have focused on the aluminum alloy. In this study, Al6061-T6 alloy plates having 5 mm of thickness were welded under nine different conditions from three tool rotation speeds: 900, 1000 and 1100 rpm, and three feed rates: 270, 300 and 330 mm/min. Specimen size of Micro Shear Punch(MSP) test was $10{\times}10{\times}0.5mm$. The mechanical properties were evaluated by MSP test and Analysis of Variance (ANOVA). The specimens were classified by advancing side(AS), retreating side(RS), and center(C) of width of tool shoulder. The optimal welding condition of FSW based on micro strengh was obtained when the tool rotation speed was 1100 rpm and the feed rate was 300 mm/min. The maximum load measured AS, RS, and C in the weldment was measured 554.7 N, 642.9 N, and 579.2 N, respectively.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.265-270
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• 1972

An attempt was made in this study to investigate the possibility of processing squid along with pork into an intermediate moisture food, as an acceptable new item in Korea. To obtain a palatable and low cost product, portions of mixture consisting of equal amounts of ground squid and pork were cooked in soy sauce for 20 min, soaked in glycerol for 20 min at $80^{\circ}C$, and then air dried for 90 min at $60^{\circ}C$. During storage for 42 days in saturated humidity incubator at $37^{\circ}C$, the total microbial counts of the products packaged in polyethylene (0.05 mm), polypropylene (0.05 mm) and plastic laminated aluminum foil were decreased from 230 per gram to 40, 20 and 10 per gram respectively. In another long range storage test of 6 months, the results paralleled the above trends. Even though the TBA value of the samples increased during the storage, it was not so serious as to damage on the organoleptic quality of this product. The results indicate that stored product was as acceptable as the freshly prepared one.

• Nuclear Engineering and Technology
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• v.40 no.6
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• pp.497-504
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• 2008

In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica ($SiO_2$), calcium oxide (CaO) and aluminum oxide ($Al_2O_3$). Furthermore, calcium fluoride ($CaF_2$), magnesium oxide (MgO), and ferric oxide ($Fe_2O_3$) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding $5.5{\times}10^3$. The slag formers containing calcium fluoride ($CaF_2$) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium.