• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.233-244
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• 2006

Of many volatile organic detergents for metals, benzine(CAS No. 8030-30-6), of which the toxicity has not yet been proven, has been used as an alternative of the halide compounds in the consideration of toxic effects, global warming and the destruction of ozone layer. In order to evaluate the effects of the benzine on human body by investigating the subchronic inhalation toxicity, to obtain the basic data for establishing the criteria of exposure in working environments and to classify the hazardousness in compliance with the Industrial Safety and Health Act by evaluating the hazardousness, repeated inhalation exposure test was carried with SD rats. The rats were grouped by 10 females and males each. The repetitive inhalation exposures were carried out at 4 levels of concentration of 0 ppm, 60 ppm, 300 ppm, and 1,500 ppm, for 6 hours a day, 5 days a week, for 13 weeks. The results are described hereunder. 1. No death of the animals of the exposed and controlled groups in the test period. Not any specific clinical symptoms, change in feed intake quantity, abnormality in eye test, or change in activity were observed. 2. In the 300 ppm and 1,500 ppm groups, weight reduction in the female groups and weight increase of liver and kidney in the male groups compared with control group were observed with statistical significance(p<0.05). 3. In the blood test, the HCT increased in the male 300 ppm group and the number of hematocyte increased, MCV and MCH decreased in the male 1,500 ppm group. In the female 1,500 ppm group, the HB decreased and the distribution width of the hematocyte particle size increased. In the blood biochemistry test, the TP in the male 1,500 ppm group and the LDH in the female 1,500 ppm group were increased with statistical significance(p<0.05). 4. Under the test conditions of the present study with SD rats, the NOEL was evaluated to be from 60 ppm to 300 ppm for both male and female groups. By extrapolation, the NOEL for human who work 8 hours a day was evaluated to be from 128 ppm to 640 ppm 5. Since the NOEL evaluated in this study do not exceed 60ppm(0.184 mg/L) the test material does not belong to the classification of the hazardous substance "NOEL${\leq}$0.5mg/L/6hr/90day(rat), for continuous inhalation of 6hours a day for 90 days" nor to the basic hazardous chemical substance class 1(0.2 mg/L/6hr/90day(rat) defined by the GHS which is a criteria of classification and identification of chemical compounds. However, considering the boiling point($30-204^{\circ}C$), flashing point($-40^{\circ}C$), vapor pressure(40 mmHg), and the inflammable range(1.0 - 6.0 %), sufficient care should be taken for handling in the safety aspects including fire or explosion.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.3
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• pp.224-234
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• 2007

This study aimed to examine the harmful effects of Mn and Fe, which may be generated as dust or fume in the industrial sites, on the body and genital organs by their inhalation. It is intended to find the characteristics and differences of the hazardousness by inhaling a single and the mixed materials of Mn and Fe. Male F344 rats were divided into the control group and 3 exposed groups on the basis of the test material compound (Mn $1.5mg/m^3$, Mn 1.5 and Fe $3.0mg/m^3$, Fe $3.0mg/m^3$). The 4 groups were divided into 4 subgroups again on the basis of the exposure period (4 and 13 weeks) and the recovery period (4 and 13 weeks). The exposure condition was 6 hours a day, 5 days a week for the whole body. Clinical tests including changes in weight and feed rate, blood biochemical test, motility change, changes in the number and the amount of spermatozoon (sperm count), daily sperm production (DSP), deformity test of spermatozoon and changes in the accumulation of Mn and Fe in blood and internal organs were performed. Motility was reduced by Mn exposure. Especially, the effect of Mn was exposure period responsible. By mixing with Fe, no significant change in motility Mn and Fe accumulation in organs was observed. Sperm count and daily sperm production (DSP) were decreased by Mn. Additional effect like the reduction of sperm count and DSP, and delayed restoration of sperm count and DSP during the recovery period were observed in the mixed exposure group. These results indicate that Mn and Fe may affect the motility reduced and has male reproductive toxicity. Mixed exposure of Mn and Fe lead to synergic effects on the male reproductive toxicity.

• 대한공업교육학회지
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• v.33 no.2
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• pp.259-272
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• 2008

In order to improve the productivity and quality of boat's mold in leisure boat industry, the development of modelling and machining technology of leisure boat's plug is strongly required. The traditional lines drawing approach by hand required the designer to both create fair curves and to make sure that the curves matched up to each other in the three main drawing views: profile, plan, and section. However, one will find when studying lines drawings in books that the curves might look smooth and fair, but the lines do not agree exactly in the three views. Therefore, the 2 dimensional drawing data of leisure boat are transformed using 3 dimensional design s/w and CAM s/w. In addition, the leisure boat is designed with a 3 dimensional s/w. The NC cutting data are generated by the CAM s/w. The surface characteristics of machined surface are investigated at various cutting conditions such as spindle speed, feed speed, and cutting material.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.4
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• pp.599-605
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• 2016

In this study, two experiments were conducted to investigate the physicochemical characteristics (Exp. I) of bedding materials such as rice hulls (RH), sawdust (SD), wood shavings (WS) and sawdust+wood shavings (S+W; 1:1 in volume), and utilization of these beddings except RH (Exp. II) for rearing beef cattle. In Exp. I, the distribution of particle size (%) with $250{\mu}m$ and below $250{\mu}m$ was greater (p<0.05) in SD (30.4) than RH (4.4), WS (18.8) and S+W (20.1). Bulk density ($kg/m^3$) of bedding materials was directly proportional to the percentage of $250{\mu}m$ and below $250{\mu}m$ particles, 178, 46, 112, and 88 for SD, WD, S+W and RH, respectively. Water absorption rate (%) after submersion in water for 24 h was higher (p<0.05) in WS (540.2) compared to SD (270.2), S+W (368.2). The S+W had an intermediate value of the absorption rate between SD and WS, but had an outstanding durability of water absorption capacity. Moisture evaporation rate (%) for 12 h was higher (p<0.05) in WS (75.4) than SD (70.5), S+W (72.2) and RH (57.8). Average ammonia emission ($mg/m^2/h$) for 36 h was higher (p<0.05) in RH (3.15) than SD (1.70), WS (1.63), and S+W (1.73). In Exp. II, thirty six Hanwoo cows were allocated in 9 pens with one side on feed bunk side (Side A) and another side equipped with water supply (Side B) for 3 weeks with duplicated periods. Average moisture concentrations (%) of beddings were higher (p<0.05) in WS (side A, 65.7; side B, 57.9) than SD (side A, 62.5; side B, 52.2) and S+W (side A, 61.6; side B, 50.7). Regardless of types of beddings, moisture concentrations (%) of beddings within a pen were lower (p<0.05) at side B than A, implying longer period of utilization. These results suggest that using S+W would be a better choice than SD or WS alone, considering physicochemical characteristics and economics, and RH is not a suitable material as a bedding for beef cattle.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.535-541
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• 2017

On the basis of 200 ppm of Ag and 120 l/h of feed flow rate, we built a pilot plant of an ion exchange fiber system having an double tube type ion exchange chamber with strong base ion exchange fiber (FIVAN A-6) which was designed to replace fibers easily and to eliminate the need for a fixture. The following results were obtained for the double tube type of ion exchange fiber system with an ion exchange capacity of 4.6 meq/g for Ag. The adsorption process was operated in the range of 40~90 l/h after confirming the effect of the flow rate and, pH did not affect formation of complex ion of Ag in the range of pH 7~12. In the case of backwash process, the recovery rate of Ag was tested in the range of 60~120 l/h and comparative experiments were carried out using NaOH, $NH_4Cl$, and NaCl as the chemicals for backwash. Although the desorption time was shortened at higher concentration, the desorption efficiency per mol was lowered. Therefore, it was confirmed that the desorption time and the concentration should be well balanced to operate economically. The desorption pattern of the backwash process is slower than the adsorption process and takes a lot of time. The results showed that the Ag adsorption ratio was 99.5% or more and the Ag recovery ratio was 96% or more, and commercialization was possible.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.108-108
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• 2009

Precipitation hardening nickel base alloys strengthened by intermetallic compounds are extensively used to manufacture on the components of the hot section of gas turbine engines. To ensure structural stability and maintenance of strength properties for a long time, nickel alloys are normally subjected to complex alloying with elements to form ${\gamma}'$(gamma prime). Such alloys have a limited weldability, are normally welded in high temperature. However, laser welding have a merit that applies in room temperature as easy control of welding parameter and heat input. In this study, $CO_2$ laser welding is applied on STS304 plate with good ductility and precipitation hardening nickel base alloy (GTD111DS) used blade material. Also, several welding parameters are applied on powder, power and travel speed. There are no cracks in Rene 80 and IN 625 powder when STS304 plate is used. But IN 625 powder has no cracks and Rene 80 have some cracks in welds with GTD111DS substrate. Adjusting of welding parameter is tried to apply Rene 80 having a good strength compare to IN 625. In the result of adjusted welding parameter, optimized welding parameters are set with low power, low feed rate and high welding speed. Tensile strength of GTD111DS substrate with Rene 80 powder is same and over than the one of base metal in room temp and high temp($760^{\circ}C$).

• Korean Journal of Poultry Science
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• v.30 no.4
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• pp.253-257
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• 2003

The suitability of processed cardboard(PC) as litter of broiler house was evaluated by comparing the growth performances of broiler chicks reared on the PC with those of birds reared on conventional rice hull litter(RH) as the control group. A total of 180 male broiler chick (5d old, Ross) were randomly divided into 2 groups and placed into 2 types of litter, PC and RH, with 3 replicates of 30 birds per replicate. Commercial broiler feeds and water were provided ad libitum for 5 weeks. The body weight gains of the birds reared on PC were heavier than those on RH(P<0.05). The average feed conversion rate of chicks reared on PC was appeared to be improved as compared to that of the control. The Enterobacter aerogens counts in PC were significantly rduced than those in the control litter(P<0.05), but a total number of Salmonella and E. coli were not affected by the litter materials. No difference was observed between the average moisture contents of the litters. The average mortality of the chicks reared on PC was significantly lower than that of RH(P<0.05). The results indicate that processed cardboard can substitute other conventional litter materials when the others are in short supply or expensive.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.29-34
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• 2015

Hydrocarbon resins, which are defined as low molecular weight, amorphous, and thermoplastic polymers, are widely used as tackifier for various types of adhesives, as processing aids in rubber compounds, and as modifiers for plastics polymers such as isotactic polypropylene. Typically, hydrocarbon resins are non-polar, and thus highly compatible with non-polar rubbers and polymer. However, they are poorly compatible with polar system, such as acrylic copolymer, polyurethanes, and polyamides. Moreover, recently the raw materials of hydrocarbon resin from naphtha cracking had been decreased because of light feed cracking such as gas cracking. To overcome this problem, in this study, novel hydrocarbon resins were designed to have a highly polar chemical structure which material is sustainable. And, it was successfully synthesized by Diels-Alder reaction of dicyclopentadiene monomer and sorbic acid from blueberry as renewable resources. Acrylic resins were formulated with various tackifiers solution including sorbic acid grafted hydrogenated dicyclopentadiene hydrocarbon resins in acrylic adhesive and rolling ball tack, loop tack, $180^{\circ}$ peel adhesion strength, and shear adhesion strength were measured. The properties depend on the softening point and polar content of tackifiers.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.130-133
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• 1999

Body fat-reducing ability of oyster mushroom (Pleurotus ostreatus) water extract (OMWE) was investigated of mice by supplying it drinking water. OMWE(2.95% solid content ) was prepared by extracting a low grade of the mushroom at 12$0^{\circ}C$ for 10min. The solid material of OMWE was composed of 65.2% reducing sugar, 0.23% crude fat, 0.5%total protein, 1.2% ash and 32.9% others. OMWE was appropriately diluted with drinking water. Seventy two male ICR mice(25$\pm$1 g, 7~8 weeks of age, 6 mice/cage, 18 mice/treatment) housed in polycarbonate cages containing $\beta$-chips were adopted in a temperature-and humidity-controlled facility with free access to water and diet. One week later, the mice were subjected to one of the treatments for 36days : 0 (control), 10, 50 and 100% OMWE. Drinking wter with or without OMWE was supplied twice (40ml each, 80ml in total ) daily per cage. Body weight and fed intake were recorded every three days. At the end of the experiment, mice were sacrificed to determine the chemical composition (fat, protein, ash and water). Body weight of mice treated with OMWE (10, 50 and 100%) at day 36 was 35.9, 35.9and 35.5g per mouse , respectively, and not significantly reduced as compared to that (36.5g/mouse) of control mice. Average body fat of 0,10,50 and 10% OMWE -treated mice was 14.3, 13.1, 10.7 and 12.0% , respectively. Body fat reduction by 50% OMWE treatment was 25.2% (p<0.05) relative to control. OMWE did not affect feed intake. The contents of body protein and ash were increased with respect to body fat decrease, while water content was not changed much. These results suggest that OMWE could reduce body fat of the mice without body weight change, giving the best effect by 50% OMWE.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.7-14
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• 2004

This study was carried out to survey and confirm the occurring sites of Parnassius bremeri in Korea, and to investigate ecological characteristics to develop a mass rearing technique. In the field survey, adults were found in the two previously known sites in Gyungnam Province and another site was newly found in Samcheok, Gangwon Province. Emergence period of adults was from middle of May to middle of June. Oviposition took place on various material, including hostplant, debris, dead leaves, etc. Eggs were laid singly, up to 126.7 eggs per female. The egg-period was 221.3${\pm}$2.3 days, eggs were hatched from 11th to 22nd of January in the natural condition, and started to feed for about 10 days after hatching. Survival rate of the 1st larvae was 67.6%. Developing period of each instar in the insectary (25$^{\circ}C$, 75% RH, 16L:8D) was 11.2 days for the 1st instar, 7.3 days for 2nd, 12.8 days for 3rd, 16.2 days for 4th, and 18.2 days for 5th, and the pupal period was 21.3 days. The average longevity of adults was 26.2 days. Oviposition rate was higher in the natural condition with enough space to fly for 3♀ : 1 ♂ coupled, at least 3 ${\times}$ 3${\times}$4 m-sized room, than in smaller cage. In a comparison of the preference for visiting on sugar source, black sugar and fructose were effective.