• Korean Journal of Ichthyology
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• v.19 no.3
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• pp.201-209
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• 2007

The fine structures and histochemical features on the integumentary system of the grass puffer, Takifugu niphobles were examined by means of the light and transmission electron microscopy. Integumentary surface of the grass puffer showed irregular folds in light microscope. The folds of the ventral region are more pronounced than those in the dorsal region. Integumentary system is composed of outer epidermal layer and inner dermal layer. The stratified epidermal layer consists of epithelia, mucous cells, club cells, granular cells and multivacuolar gland. Epithelial cells are classified into superficial, intermediated and basal cell, and free surface of superficial cell is covered with microridges. Glands of the epidermal layer are divided into unicellular and multicellular gland. Mucous cells of multicellular gland contains mucosal materials of neutral glycoprotein. Multivacuolar gland is composed of numerous vacuole cells of about $20{\mu}m$ in axial diameter. Vacuole cells contains a large central vacuole and are connected to another by many desmosomes. The mucous glands and multivacuolar glands are more abundant in ventral region than dorsal integument. The thickness of dermis is more three to five times than epidermis in ventral integument. The collagen fibers, fibrocytes, nerve cells, basal plate of spine and chromatophore are observed in the dermal layer of compact connective tissue.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1397-1398
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• 2007

본 연구는 $SF_6$와 Dry-air(건조공기), $N_2$, $CO_2$ 가스가 혼합된 절연매체의 절연 특성과 부분방전 특성 연구를 기초실험용 쳄버와 70kV급 GIS mock up을 이용하여 교류전압을 인가하여 실험이 수행되었다. 전자의 경우, Sphere gap 및 Needle/Plate 전극시스템을 이용하여 순수 $SF_6$가스와 Dry-air, $N_2$, $CO_2$ 가스들의 절연내력을 비교하고, 챔버의 압력을 5기압으로 유지한 상태에서 Dry-air, $N_2$, $CO_2$와 $SF_6$가스의 혼합비를 변화시키면서 절연내력이 측정되었다. 후자의 경우, 기초실험에서 도출된 $SF_6$가스와 Dry-air, $N_2$, $CO_2$의 최적의 혼합비율을 선택한 후, 방전 개시전압과 부분방전 양상을 순수 $SF_6$가스의 결과와 비교분석하기 위한 실험을 수행하였다. 이를 위하여 GIS 사고의 주요원인이 되는 결함들, 즉 Protrusion, Floating, Free moving particle 들을 인위적으로 모의하여 Mock up 내부에 설치하고 내부 압력을 5기압으로 유지한 상태에서 수행되었다. 전자의 경우, $0.5{\sim}5$ 기압 범위 내에서 Dry-air, $N_2$, $CO_2$ 압력을 변화시켰을 때 절연내력은 전극시스템에 무관하게 순수 $SF_6$가스의 결과치의 Dir-air $47{\sim}51%$, $N_2\;48{\sim}61%$, $CO_2\;47{\sim}60%$ 정도이다. 또한 챔버 압력이 5기압인 상태에서 Dry-air, $N_2$, $CO_2$가 80% 혼합된 절연매체는 순수 $SF_6$가스 절연내력의 80%이상의 절연내력을 가지고 있다. 후자의 경우, 인가전압을 고정 시켰을 때, 부분방전 패턴과 방전크기는, 순수 $SF_6$가스와 Dry-air 가 80% 혼합된 절연매체는 동일한 패턴과 방전크기를 나타내고 있다. 이러한 결과를 근거로, 가스 압력이 5기압에서 운전되는 전력기기의 절연매체로서 혼합가스를 사용할 경우, $SF_6$가스와 Dry-air, $CO_2$, $N_2$ 가스들의 혼합비는 2:8정도가 적절한 것으로 제안한다.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.542-547
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• 2021

Glass lined impellers are corrosion resistant to most chemicals, including strong acids, and also have a smooth, non-stick surface, easy to clean and free from impurities in the process. Glass lined home base impeller is a multi-purpose impeller designed to stir a wide viscosity range of liquids from low viscosity fluids to high viscosity fluids, among others, cell culture, yeast culture, and beer fermentation pots, especially used for air-water system breathable stirring. The glass lining for HB impellers, which are simple in structure and competitive in performance, is essential to have upper and lower division in order to make the joint area between the impeller and shaft as small as possible. The upper and lower division of the impeller hardly affects the mixing performance, but the aeration performance. In this study, in order to optimize the shape of the Glass Lining HB impeller, a study was conducted on the effect of the angle between the upper and lower impellers, the clearance between the impellers, and the number of baffles on the aeration power. The optimal shape and baffle plate conditions for the Glass lined HB impeller were derived through the study results that the angle and the clearance between the upper and lower impellers decreased the ration of the power consumption with aeration P_g and that without aeration P₀, P_g/P₀.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.630-635
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• 2022

Copper(II) oxide (CuO), electroless plated on a nitrogen-containing carbon sponge prepared by a melamine sponge thermal treatment, was developed as a nitric oxide (NO) gas sensor that operates without a wafer. The CuO content on the surface of the carbon sponge increased as the plating time increased, but the content of nitrogen known to induce NO gas adsorption decreased. The untreated carbon sponge showed a maximum resistance change (5.0%) at 18 min. On the other hand, the CuO plated sample (CuO30s-CS) showed a maximum resistance change of 18.3% in 8 min. It is considered that the improvement of the NO gas sensing capability was caused by the increase in hole carriers of the carbon sponge and improved movement of electrons due to CuO. However, the NO gas detection resistance of the CuO electroless plated carbon sponge for 60 s decreased to 1.9%. It is considered that the surface of the carbon sponge was completely plated with CuO, resulting in a decrease in the NO gas adsorption capacity and resistance change. Thus, CuO-plated carbon sponge can be used as an effective NO gas sensor because it has fast and excellent resistance change properties, but CuO should not be completely plated on the surface of the carbon sponge.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.587-592
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• 2021

Change in the cortical thickness of long bones occurring with aging and osteoporosis is known to be a risk factor for fracture. The present study aims to investigate the dependencies of phase velocities of ultrasonic guided waves on the cortical thickness in 7 soft tissue-bone mimicking phantoms consisting of acrylic plates covered by a 2 mm-thick silicone rubber layer by using the axial transmission technique with a pair of transducers with a center frequency of 200 kHz and a diameter of 12.7 mm. Two distinct propagating waves with different velocities, the First Arriving Signal (FAS) and the Slow Guided Waved (SGW), were consistently observed for all the soft tissue-bone mimicking phantoms. The FAS velocity decreased slightly with increasing thickness, whereas the SGW velocity increased strongly with increasing thickness. The FAS and the SGW velocities were found to be closely consistent with the S0 and the A0 Lamb mode velocities for a free acrylic plate, respectively, suggesting that the presence of the soft tissue mimicking material (2 mm-thick silicone rubber layer) covering the acrylic plates does not influence significantly the velocity measurements.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.46-53
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• 1996

Background: Endotoxin or lipopolysaccharide(LPS) can prime phagocytic cells such as polymorphonuclear leukocytes, monocytes or animal peritoneal macrophages to generate increased amounts of secretory products such as oxygen free radicals and tumor necrosis factor, which play an important role in developing adult respiratory distress syndrome in gram negative sepsis. Human alveolar macrophages(HAM) are continuously exposed to various stimuli inhaled into the alveoli, and the response to LPS might be different in HAM. Therefore, we investigated the effect of LPS pre-exposure on HAM adhered to plastic surface and A549 cell(type II human alveolar epithelial cell line) monolayer. Methods: HAM were isolated from bronchoalveolar lavage fluid from normal lung of the patients with localized lung cancer and esophageal cancer. LPS was exposed to HAM for 2hrs before or after adherence to plastic surface of 24-well Linbro plate and A549 cell monolayer. And then HAM was stimulated with PMA(phorbol myristate acetate) or fMLP(N-formyl-methionylleucyl-phenylalanine). The amount of hydrogen peroxide($H_2O_2$) production in the supernatant was measured on the principle of peroxidase-dependent oxidation of phenol red by hydrogen peroxide. Results: LPS pre-exposure could not enhance $H_2O_2$ production in neither HAM adhered to plastic surface nor one to A549 cell monolayer. But LPS even in the absence of PMA or fMLP stimulation directly increased $H_2O_2$ release in HAM if added after the adherence to A549 cell monolayer. Conclusion: Endotoxin does not prime HAM, but may directly activate HAM adhered to alveolar epithelial cells. Further investagation will be necessary.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.515-520
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• 2007

This study was peformed to determine the antioxidative, antimutagenic and cytotoxic effects of the natural seasoning using Lentinus edodes powder (NSLP) by DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical donating method, Ames test, and cytotoxicity, respectively. The scavenging effect on DPPH radical in ethyl acetate fraction of NSLP showed $155{\mu}g\;of\;RC_{50}$. The direct antimutagenic effects of ethanol extract and its solvent fractions of NSLP were examined by Ames test using Salmonella Typhimurium TA98 and TA100. In the Ames test, ethanol extract of NSLP alone did not exhibit any mutagenicity and most of the samples showed high antimutagenic effects against mutation induced by N-methyl-N'-nitro-N-nitroso guanidine (MNNG) and 4-nitroquinoline-1-oxide (4NQO). Ethyl acetate fraction of NSLP ($200{\mu}g/plate$) showed approximately 82% inhibitory effect on the mutagenesis induced by 4NQO against TA98 strain, whereas 84% and 80% inhibitions were observed on the mutagenesis induced by 4NQO and MNNG against TA100 strain. In anticancer effects of ethanol extract and its solvent fractions of NSLP against cancer cell lines including human lung carcinoma (A549), human breast adenocarcinoma (MCF-7), human hepatocellular carcinoma (Hep3B), human cervical adenocarcinoma (HeLa) and human gastric carcinoma (AGS) were investigated. The treatment of 1 mg/mL ethyl acetate fraction of NSLP showed strong cytotoxicity of 56.7%, 84.9%, 64.6%, 85.1% and 71.5% against A549, MCF-7, Hep3B, HeLa and AGS, respectively. In contrast 1 mg/mL treatment of NSLP extract and its solvent fractions had only $4{\sim}40%$ cytotoxicity on human transfomed primary embryonal kidney cell (293). From this result, it is suggested that NSLP is believed to have possible antioxidative, antimutagenic and anticancer capacities.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.145-153
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• 2009

The purpose of this study was to evaluate the effect of instrument compliance on the polymerization shrinkage stress measurements of dental composites. The contraction strain and stress of composites during light curing were measured by a custom made stress-strain analyzer, which consisted of a displacement sensor, a cantilever load cell and a negative feedback mechanism. The instrument can measure the polymerization stress by two modes: with compliance mode in which the instrument compliance is allowed, or without compliance mode in which the instrument compliance is not allowed. A flowable (Filtek Flow: FF) and two universal hybrid (Z100: Z1 and Z250: Z2) composites were studied. A silane treated metal rod with a diameter of 3.0 mm was fixed at free end of the load cell, and other metal rod was fixed on the base plate. Composite of 1.0 mm thickness was placed between the two rods and light cured. The axial shrinkage strain and stress of the composite were recorded for 10 minutes during polymerization. and the tensile modulus of the materials was also determined with the instrument. The statistical analysis was conducted by ANOVA. paired t-test and Tukey's test (${\alpha}<0.05$). There were significant differences between the two measurement modes and among materials. With compliance mode, the contraction stress of FF was the highest: 3.11 (0.13). followed by Z1: 2.91 (0.10) and Z2: 1.94 (0.09) MPa. When the instrument compliance is not allowed, the contraction stress of Z1 was the highest: 17.08 (0.89), followed by FF: 10.11 (0.29) and Z2: 9.46 (1.63) MPa. The tensile modulus for Z1, Z2 and FF was 2.31 (0.18), 2.05 (0.20), 1.41 (0.11) GPa, respectively. With compliance mode. the measured stress correlated with the axial shrinkage strain of composite: while without compliance the elastic modulus of materials played a significant role in the stress measurement.

• Food Science and Preservation
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• v.14 no.2
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• pp.220-225
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• 2007

This study was performed to measure the antioxidative, antimutagenic, and cytotoxic properties of Prunus armeniaca using the DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical donating method, the Ames test, and cytotoxicity measurements, respectively. Electron-donating abilities were 48.3, 43.9, 14.8 and 12.9 per g dry matter of P. armeniaca seed (PAS), P. armeniaca flesh(PAF), butylated hydroxytoluene, and ${\alpha}-tocopherol$, respectively. The direct antimutagenic effects of an ethanol extract of P. armeniaca were examined in Ames tests using Salmonella typhimurium TA98 and TA100 as reporter organisms. In the Ames test, the ethanol extract of P. armenicaca alone did not exhibit any mutagenicity but the extract did show substantial inhibitory effects against mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) and 4-nitroquinoline-1-oxide(4NQO). The ethanol extract of PAS(200g dry matter/plate) inhibited strain TA98 mutagenesis induced by 4NQO by ca. 37.9%, and mutation inhibition values of 42.1% and 69.4%, respectively, were observed when 4NQO and MNNG acted on the TA100 strain. The cytotoxic effects of ethanol extracts of P. armeniaca against cell lines of human lung carcinoma(A549), human breast adenocarcinoma(MCF-7), human hepatocellular carcinoma(Hep3B), human cervical adenocarcinoma(HeLa), and human gastric carcinoma(AGS) rose with increases in extract concentration. An ethanol extract(4mg/mL dry matter) of PAF showed strong cytotoxicities of 88.2%, 58%, 72.8%, 89.4%, and 91.9% against A549, AGS, MCF-7, HeLa, and Hep3B cells, respectively. In contrast, the same extract showed only 13 37% cytotoxicity for a nomal human kiney cell line(293). It is suggested that P. armeniaca possesses useful antioxidative, antimutagenic, and anticancer properties.

• the MEAT Journal
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• s.34 winter
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• pp.14-25
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• 2007

The objective of this study was to investigate the physicochemical, microbiological and sensory properties of food additive-free grilled pork products manufactured using loin (T1), tender loin (T2) and ham (T3). The samples were heated for 30 min at $60^\circC$, and then 50 min for $150^\circC$. After cooling, vacuum packaged grilled pork samples was stored at $4\pm$$1^\circC$ for 40 days. The pH values of grilled pork samples ranged from 5.92 (T1) to 6.10 (T3) at the initial storage time, and from 6.28 (T1) to 6.60 (T3) after 40 days. The water holding capacities (%) was 85.99~93.24% for T1, 85.26~93.89% for T2 and 89.11~94.67% for T3, all of which were slightly higher than those of other pork products. The shear force values of T2 were significantly higher (p<0.05) than those of the other pork products throughout the storage period. The TBARS and VBN values of T2 were significantly higher (p<0.05) than those of T1 and T3. With regard to microorganisms, all grilled pork samples was in good condition, showing 1.93~3.48 log10 CFU/g via total plate counts, and 1.74~3.48 log10 CFU/g for lactic acid bacteria throughout the storage period. Regarding sensory evaluation, the scores of overall acceptability in all products were above 5.0 points through 40 days of storage.