• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.688-694
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• 2009

A spray-type cleaning agent in utilizing dust-remover on PCB was chosen to study the cleanliness test and efficiency. In order to choose alternative environmental-friendly cleaning agents, it is important that the systematic selection procedures should be introduced and applied through the evaluation of their cleaning ability, environmental characteristics, and economical factors, and that the objective and effective evaluation methods of cleanliness should be established for the industry. A novel cleaning evaluation method with scanning electron microscopy/energy-dispersive X-ray analysis of surface observation evaluation method and an infra-red thermography camera(THERMOVISION A20 model) was studied in this work. The sound card(CT-2770 model) cut by $2{\times}2cm$ size was used as a part, and before and after the spray cleaning, the cleanliness was observed by the image analyzer of SEM and further the removal efficiency of dust was quantitatively evaluated by the component analysis of EDX. For the parts of P4TE model motherboard and IPC-A-36 PCB plate, before and after the spray cleaning, temperature differences were measured and compared at room temperature and 50 oven temperature by an infra-red thermography camera in the contaminants of dust and iron powder.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.694-699
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• 1997

Normal-phase HPLC was used to separate the useful phospholipids, PE, PI and PC in soybean lecithin. The mobile phase used in this experiments were haxane, isopropanol and methanol, the gradient mode was applied as the three components could not be separated by the isocratic mode. To find the optimum separation condition, the concentration profiles of effluents were calculated from the plate theory and the capacity factor in step-gradient mode. From the calculated results, PE was separated with hexane/isopropanol/methanol = 90/5/5vol.% in isocratic mode and PI and PC were resolved in the conditions of 10min gradient time and the second mobile phase of hexane/isopropanol/methanol=50/20/30vol.% in step-gradient mode. The agreement between the calculated concentration profile and experimental data was good, so the methodology developed in this work can be used to obtain the optimum separation condition in gradient mode.

• Journal of Korean society of Dental Hygiene
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• v.12 no.3
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• pp.641-646
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• 2012

Objectives : The purpose of this study is to analyze the sterilizing effects of toothbrushes by administering bacteria into toothbrushes and reproducing the antibacterial effects using a microwave oven. Methods : The heads of four-row mid-strength toothbrushes were cut, put in a bacterial solution ($3{\times}10^9cells/ml$) for vortexing, and sterilized with microwaves for 0, 30, and 60 seconds. They were then moved into four tubes containing DW 10 ml and suspended in a vortex mixer for two minutes to separate bacteria from them. DW 9ml was added by 1ml of bacteria for dilution of $10{\sim}10^6$ times. It was then administered to the BHI agar plate by 0.1ml and cultured at $37^{\circ}C$ for 24 hours. Total number of bacteria adhered to a toothbrush was obtained by multiplying the number of colonies by the dilution factor. The experiment was done in the first, second, and third step, being repeated in a normal temperature drier ($23^{\circ}C$) after 5, 9 and 24 hours. Results : The results of the experiment revealed that the sterilizing effects were 95% or over. When toothbrushes were sterilized for 60 seconds, the number of colonies is about 11 after drying for 5 hours, 7 after drying for 9 hours and 2 after drying for 24 hours. The sterilizing effects reached 98% when the bacteria-administered toothbrush was sterilized for 1 minute after drying for 24 hours. Conclusions : The results demonstrated that toothbrush sterilizing by using microwave is a suitable way to prevent cross-contamination of toothbrushes by oral bacterial infection and thus easy to use at home. However, this study suggests that toothbrush sterilizing by using microwave should be limited within two times a week because the physical properties of toothbrush might be changed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.230-237
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• 2003

For hygenic evaluation, microbiological tests of seasoned raw vegetal)les from five high school foodservice operations were conducted. The antimicrobiological effect of pre-preparation with vinegar against microorganisms on vegetables in foodservice operations was also investigated. Total plate counts of leek gukgalli, broad bellflower saengchae and vegetable salad ranged from 10$^4$ CFU/g to 10$^{6}$ CFU/g. Coliform levels of those ranged from 10$^2$CFU/g to 10$^4$ CFU/g. Leek washed three times was pre-prepared at different concentration (0.05%,0.1%,0.5%,1% and 2%) and temperature ( 1$0^{\circ}C$ 2$0^{\circ}C$ and 4$0^{\circ}C$) for 5, 10 and 30 minutes. The higher the concentration and temperature of vinegar were, the more the antimicrobiological activity increased. The sanitizing activity of vinegar increased with treatment time. Considering the quality of vegetable and the expense, when the levels of total plate counts and coliform of vegetable were 10$^{6}$ and 10$^3$ CFU/g, pre-preparation with 0.5% of vinegar at 2$0^{\circ}C$ for 10 minutes was best. The population of total plate count and coliform on row and leek washed three times increased during storage for 72 hours. However, The levels of microorganism on leek samples pre-prepared with 0.5% and 1% vinegar decreased during storage. After the treatment of vinegar at 1$0^{\circ}C$ for 10 minutes, Staphylocucus aureus, Escherichia coli O157, Shigella sonnei, Salmonella entritidis, Listeria monolytogenes were not detected.

• Animal Systematics, Evolution and Diversity
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• v.5 no.2
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• pp.107-119
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• 1989

Three species of Korean sticklebacks family Gasterosteidae were reviewed based on the specimens of several populations for the study of their morphological variations and taxonomical positions. All specimens of Gasterosteus aculeatus observed have a complte row of lateral plates ranging from thirty-two to thirty-five in number. The low-plate morph regarded as landlocked type is virtually absent. And no difference was recognized among six populations of G. aculeatus in the meristic chracters, i.e. number of vertebrae, gill rakers and finrays. The Pungitius sinensis and P.kaibarae ssp. shown local variations have scutes ranging from 31 to 35, but not clinal in the morphometric characters. But P.sinensis was statistically different from P.kaibarae ssp. in some characters such as the number of dorsal spine rays and vertebrae, and body depth, although their ranges overlapped. No significant taxonomic difference was detected between white from and black from in dorsal spinous membrane of P.kailbarae ssp. Although these three species of Korean sticklebacks have the same diploid chromosome number (2N=42), G. aculeatus is obviously different from the two species of genus Pungitius in their karyotype ; G. aculeatus consists of six metacentrics, six submetacentrics, and thiry subtelo-acrocentrics, and both P.sinensis and P.kaibarae ssp. have four metacentrics, six submetacentrics, and thirty-four subtelo-acrocentrics.

• Journal of Advanced Technology Convergence
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• v.1 no.2
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• pp.11-17
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• 2022

The purpose is to find out where medical workers can receive the minimum radiation does in clinical. In order to sett RQR standard quality of radiation, put a Al 1.5mm filter(row and column: 10 cm × 10 cm) on X-ray tube. Al 0.9 mm, Cu 0.3 mm, Ni 0.3 mm used as a filter. The Acrylic phantom were set to 13.1 cm, 18.5 cm, 21.1 cm. by the object thickness was different. As a results, when we use Al 0.9 mm, 1853 nSv was the highest numeral. It is a point of anode low 50 cm, when we use 13.1 cm Acrylic phantom. When we use Cu 0.3 mm, 173 nSv was the lowest numeral. It is a point of anode low 150 cm, when we use 13.1 cm Acrylic Phantom. In this study, it was confirmed that the spatial scattering dose decreased as the distance from the X-ray tube increased. It is considered that more studies on the exposure of scattered doses are needed in the future.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.1-8
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• 2008

The lateral strength test of bending type was done to investigate the lateral capacity of the double bolt connection of domestic larix glulam according to bolt spacing. In the shear specimen, which is bolted connection in the inserted plate type, the hole of bolt was made, changing the diameter of bolt (12 mm and 16 mm), the number of bolt (single bolt : control and double bolt), the direction of bolt row (in parallel to grain : Type-A and in perpendicular to grain : Type-B) and the bolt spacing (Type-A : 4 d and 7 d and Type-B : 3 d and 5 d). Lateral capacity and failure mode of bolt connection were compared according to conditions. In prototype design (KBCS, 2000), the reduction factor of the allowable shear resistance that the bolt spacing is reduced was calculated. The results were as follows. 1) Bearing stress per bolt in the single and double bolt connection of Type-A was directly proportional to bolt diameter and bolt spacing. Bearing stress of Type-B decreased as bolt diameter was increased, and decreased by 2~10% when bolt diameter was increased. 2) In the single bolt connection and the double bolt connection of Type-A, the splitted failure was formed in the edge direction. When the bolt spacing was 3 d in Type-B, bolt was yielded more in the part of tension than in the part of compression, and the splitted failure started at the bolt in the part of tension. In the 5 d spacing specimen, the bolt in the part of tension was yielded similarly to bolt in the part of compression, and the splitted failure started in the part of compression. 3) In the prototype design, the reduction factor was calculated by non-dimensionizing the yielding load in the standard of bolt spacing (Type A : 7 d and Type B : 5 d). In 12 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.87 and 0.55, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.55, respectively. In 16 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.96 and 0.76, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.77, respectively.