• Journal of Food Hygiene and Safety
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• v.24 no.1
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• pp.12-18
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• 2009

This experiment was conducted to investigate the effect of wa-song (Orostachys japonicus A. Berger) extracts on the oxidative stability of edible oil. Wa-song was dried from hot air (HWE) and freeze (FWE), and then they were extracted by hot water. The different levels (0.1, 0.5 and 1.0 g/100 mL) of HWE and FWE were added to soybean oil and lard. The chromaticity of edible oils was generally increased with prolonged heating time and HWE was higher than FWE. The anisidine value showed significant increase during heating for 48hrs. After heating for 48 hrs, it was lower than control, except for HWE added sample of 0.5 and 1.0 g/100 mL, FWE added sample of 1.0 g/100 mL. In lard, it was lower in sample added wa-song extract than control. The acid value was not significant by added amount of wa-song. Its value in HWE added sample was lower than FWE, after heating for 48 hrs. POV was lower HWE than FWE, also. After heating for 24 hrs, TBA values in soybean oil containing HWE and FWE added sample was lower than control. In lard, its value in HWE and FWE added sample was lower than control during heating for $12{sim}48\;hrs$. Therefore, those results suggested that HWE has higher antioxidant activity than FWE added sample, and then oxidative stability of HWE in edible oil was more potential for lard during its heating.

• Parasites, Hosts and Diseases
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• v.35 no.3
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• pp.171-180
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• 1997

Studies on geographical distributions and relative population densities of the vector mites of tsutsugamushi disease were carried out in October 1996 at 12 locations of the mid south inland of the Korean peninsula, where chigger mites have been never studied. Of 177 field rodents and insectivores collected. 154 (87.0%) were Apodemus ngrarius. Total 25,707 chigger mites were collected and 14 species were identified. of which Leptotrombidium pnllidum was predominant (79.8%) and L. palpate the next (8.9%) . L. pallidum, the vector species, was widely distributed in all study areas, showing the highest density at Cho-o 2-dong, Sangju-si (chigger index 201.8), and the lowest at Tanwol-dong. Chungiu-si (chigger index 40.7) . The other vector species, L. scutellare was found only at the southern part of the study area such as Yobae and Mipyong, Kumrung gun and Vnsu , Kimchon-si. The northernmost areas of the L. scutellcre distribution were coincided with the areas where actual mean air temperature is above 10.0%. Among 157 A. ograrius sera tested, 48.3% was Karp, 1.7% william and 3.3% Kuroki. The rest of the sera were not able to determine the sexto-type because of the cross antigen-antibody reactions among the tested sero-types.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.723-732
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• 1996

Cu films were deposited by chemical wapor deposition on the as-received substrates (TiN/Si) and three kinds of Cu-seeded substrates (Cu/TiN/Si) which had seeding layer in the thick ness of 5 ${\AA}$ and 130 ${\AA}$ coated by ICB(Ionized Cluster Beam) method. The effect of Cu seeding layers on the growth rate, crystallinity, grain size uniformity and film adhesion strength of final CVD-Cu films was investigated by scanning eletron microscopy(SEM), X-ray diffractometry and scratch test. The growth rate was found to incresase somewhat in the case of ICB-seeding. The XRD patterns of the Cu films on the as-received substrate and ICB Cu-seeded substrates exhibited the diffraction peaks corresponding to FCC phase, but the peak intensity ratio($I_{111}/I_{200}$) of Cu films deposited on the ICB Cu-seeded substrates increased compared with that of Cu films on the as-received substrate. The resistivity of final Cu film on 40 ${\AA}$ seeded substrate was observed as the lowest value, 2.42 $\mu\Omega\cdot$cm compared with other Cu films. In adhesion test, as the seeding thickness increased from zero to 130 ${\AA}$, the adhesion strength increased from 21N to 27N.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.175-180
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• 1998

As a part of investigation for quality improvement of surimi gel from fish with a red muscle by addition of calcium-based powder from fish bone, we investigated the processing condition of calcium-fortified mackerel surumi gel and its quality stability during storage at $5^{\circ}C$. Judging from the results of the soluble calcium content and jelly strength, the reasonable addition concentration of calcium-based powder from Alaska pollack bone for improvement of functional properties in surimi gel was revealed 0.9% on the weight basis of the chopped mackerel meat. The soluble calcium content of the calcium-fortified surimi gel (105.0 mg/100 g) was more than that of the ordinary surumi gel (2.9 mg/100 g). During cold storage of calcium-fortified surumi gel, the moisture contents, amino acid compositions, soluble calcium and phosphorus contents were little changed, the pH, volatile basic nitrogen contents, histamine contents, peroxide values and brown pigment formation were slightly increased and viable cell counts and coliform groups were not detected. The calcium-fortified surimi gel was superior in the lysine and calcium contents, EPA and DHA compositions to the ordinary surumi gel. Judging from the results, it was suggested that calcium-fortified surumi gel was nutritive, functional and safety foods.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.876-883
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• 1989

In order to investigate the index component and basis for the shelf-life of the grain share improved Meju, the effect of the storage time and package on the quality of Meju and soy sauce were studied during 90 days storage at $30^{\circ}C$. Also, sensory evaluation for the soy sauces from Meju with various storage time were carried out. During the storage period, moisture content, amylase and protease activity were decreased, on the other hand, the contents of amino-nitrogen and ammonia-nitrogen were increased. Among these components, protease activity was found the major index component for quality control because it was the most important component for soy sauce fermentation and the most changeable component of Meju during the storage period. According to the sensory test, the quality of soy sauce was agreed well with the protease activity of Meju, and the soy sauce from longer storage Meju was inferior organoleptic quality to that from shorter Meju. By the storage quality test, protease activity showed the highest value in 15 days storage Meju and decreased gradually with storage time passed. The basis of protease activity for quality control was 200 (O.D. at 660 nm/g). which was 50% of the initial activity And it was known that the shelf-life of the grain shape improved Meju was about 90 days . It was also shown that the storage in package did not affect noticeably to prolong the shelf-life of Meju on this study.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.87-87
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• 2018

다이아몬드 상 탄소(diamond-like carbon, DLC)는 상당량의 $sp^3$ 결합을 가지는 비정질 탄소(a-C) 또는 수소화 비정질 탄소(a-C:H)로 이루어진 준안정 형태의 탄소이다. DLC는 전기 저항과 굴절률이 높고 화학적으로 다른 물질과 반응하지 않으며, 마찰계수가 낮고 경도가 높아 자기 디스크, 광학 소자 등의 다양한 분야에서 적용되고 있다[1,2]. 또한 다이아몬드에 비해 상온에서 성장이 가능할 정도로 합성온도가 낮아 적용 기판의 제한이 거의 없고, 증착 방법과 조건에 따라 탄소 결합의 다양성과 비정질성이 변화하기 때문에 넓은 범위의 특성을 얻을 수 있는 장점이 있다. 지금까지 DLC 박막의 광학적 특성, 특히 굴절률, 광학적인 에너지 밴드 갭, 자외선과 적외선 투과성에 대해서는 많은 연구가 진행되었으나 가시광선의 투과성에 대한 연구는 제한적이며[4], 가시광선 투과도 개선에 대한 연구는 전무하다. 본 연구에서는 ITO 기판 위에 DLC를 합성하고 기계적 특성과 가시광선 영역 투과도를 조사하였다. RF-PECVD(radio frequency plasma enhanced chemical vapor deposition) 방법에 의해서 $C_2H_2+Ar$ 혼합 가스 비율과 $C_2H_2+N_2$ 혼합 가스 비율을 변화시켜 ITO 기판 위에 DLC 박막을 합성하였다. 공정 압력과 rf-power, 증착시간, 기판온도는 0.2 torr, 40 W, 5 분, $50^{\circ}C$로 고정하고, 공정 가스는 $C_2H_2+Ar$과 $C_2H_2+N_2$가 200 sccm이 되도록 비율을 변화하였다. $C_2H_2:Ar$과 $C_2H_2:N_2$의 비율은 180 : 20, 160 : 40, 140 : 60, 120 : 80, 100 : 100이 되도록 가스의 유량을 조절하였다. 투과도는 가시광선(380 ~ 780 nm) 범위에서 측정하였고 두께와 표면조도는 AFM으로 측정하였다. 투과도는 $C_2H_2+Ar$의 Ar 가스 비율이 증가할수록 증가해 140 : 60일 때 최댓값을 나타낸 후 다시 감소하였다. $C_2H_2+N_2$ 투과도는 $N_2$ 가스 비율이 증가할수록 감소하는 경향을 나타내었다. 표면 거칠기는 $C_2H_2+Ar$ 혼합 가스를 사용한 경우의 Ar의 가스 비율이 증가할수록 증가하였다. 그러나 $C_2H_2+N_2$ 혼합 가스를 사용한 경우에는 $N_2$ 가스의 혼합 비율이 증가할수록 감소하였다.

• Journal of Embryo Transfer
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• v.25 no.4
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• pp.229-235
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• 2010

The MTT assay is one of superior evaluation methods widely used to analyze the viability of metabolically active cell. It can be used to determine the percentage of viable sperm through measurement of the reduction of MTT granules at mitochondria in sperm tail. The purpose of this study is to determine the optimal condition of a simple and easy MTT assay to validate boar sperm viability and compare the accuracy of this test with microscopic examination. The MTT reduction rate for sperm viability were analyzed in microtiter plates (96 well) from 1 hr to 5 hr incubation periods at $37^{\circ}C$ using spectrophotometer (microplate reader) at 550 nm wavelength. The remainder of semen sample was simultaneously examined to compare the correlation of accuracy between MTT assay and other sperm parameters. Those sperm parameters were included the motility, survival rates, membrane integrity, mitochondria activity and acrosome integrity. The OD values of MTT assay (MTT reduction rates) did not greatly change at 1 hr to 5 hr incubation periods in different proportion of live and freeze-killed sperms (dead sperm). The MTT reduction rates or survival rates were decreased according to the different concentration of live and dead sperm. The linear regression at 1 hr and 4 hr incubation periods in sperm MTT assay was y=291.55x-72.176 and y= 180.64x-44.569, respectively. There are high correlation between 1 hr and 4 hr incubation periods (p<0.001). The results of MTT assay and other sperm parameters has a positive correlation (p<0.01 or 0.05). The correlation coefficients for MTT assay was 0.88115 for motility, 0.89868 for survival rates, 0.91722 for membrane integrity and 0.77372 for acrosome integrity, respectively. In conclusion, the MTT assay can be used as a reliable and efficient evaluation method for boar sperm viability. It can be use practical means to evaluate the quality of boar sperm by a fast, inexpensive and easy method.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.107-113
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• 2003

This study was carried out to improve the performance of pre-developed heat recovery devices attached to exhaust-gas flue connected to combustion chamber of greenhouse heating system. Four different units were compared in the aspect of heat recovery performance; A-, B-, and C-types are exactly the same with the old ones reported in previous studies. D-type newly developed in this experiment is mainly different with the old ones in its heat exchange area and tube thickness. But airflow direction(U-turn) and pipe arrangement are similar with previous three types. The results are summarized as follows; 1. System performances in the aspect of heat recovery efficiency were estimated as 42.2% for A-type, 40.6% for B-type, 54.4% for C-type, and 69.2% for D-type. 2. There was not significant improvement of heat recovering efficiency between two different airflow directions inside the heat exchange system. But considering current technical conditions, straight air flow pattern has more advantage than hair-pin How pattern (U-turn f1ow). 3. The main factors influencing on heat recovery efficiency were presumably verified to be the total area of heat exchange surface, the thickness of ail-flow pipes, and the convective heat transfer coefficient influenced by airflow velocity under the conditions of allowable pipe durability and safety. 4. Desirable blower capacity for each type of heat recovery units were significantly different to each other. Therefore, the optimum airflow capacity should be determined by considering in economic aspect of electricity required together with the optimum heat recovery performance of given heat recovery systems.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.518-523
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• 2010

In this study, partially stabilized zirconia was synthesized using a chemical $Y_2O_3$ stabilizer and hydrothermal method. First, $YCl_3-6H_2O$ and $ZrCl_2O-8H_2O$ was dissolved in distilled water. Y-TZP (a $Y_2O_3$-doped toughened zirconia polycrystalline precursor) was also prepared by conventional co-precipitates in the presence of an excess amount of $NH_4OH$ solution under a fixed pH of 12. The Y-TZP precursors were filtered and repeatedly washed with distilled water to remove $Cl^-$ ions. $ZrO_2$-Xmol%$Y_2O_3$ powder was synthesized by a hydrothermal method using Teflon Vessels at $180^{\circ}C$ for 6 h of optimized condition. The powder added with the Xmol%- $Y_2O_3$ (X = 0,1,3,5 mol%) stabilizer of the $ZrO_2$ was synthesized. The crystal phase, particle size, and morphologies were analyzed. Rectangular specimens of $33mm{\times}8mm{\times}3$ mm for three-point bend tests were used in the mechanical properties evaluation. A teragonal phase was observed in the samples, which contains more than 3 mol% $Y_2O_3$. The $3Y-ZrO_2$ agglomerated particle size was measured at $7.01{\mu}m$. The agglomerated particle was clearly observed in the sample of 5 mol % $Y_2O_3-ZrO_2$, and and the agglomerated particle size was measured at 16.4 um. However, a 20 nm particle was specifically observed by FE-SEM in the sample of 3 mol% $Y_2O_3-ZrO_2$. The highest bending fracture strength was measured as 321.3 MPa in sample of 3 mol% $Y_2O_3-ZrO_2$.

• Corrosion Science and Technology
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• v.9 no.4
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• pp.147-152
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• 2010

Conventional paints for conversion coating applications in steel production derived mainly from water-based polymer dispersions containing several additives actually show good general performance, but suffer from poor scratch and abrasion resistance during use. The reason for this is because the relatively soft organic binder matrix dominates the mechanical surface properties. In order to maintain the high quality and decorative function of coated steel sheets, the mechanical performance of the surface needs to be improved significantly. In fact the wear resistance should be enhanced without affecting the optical appearance of the coatings by using appropriate nanoparticulate additives. In this direction, nanocomposite coating compositions (Nanomer$^{(R)}$) have been derived from water-based polymer dispersions with an increasing amount of surface-modified nanoparticles in aqueous dispersion in order to monitor the effect of degree of filling with rigid nanoparticles. The surface of nanoparticles has been modified for optimum compatibility with the polymer matrix in order to achieve homogeneous nanoparticle dispersion over the matrix. This approach has been extended in such a way that a more expanded hybrid network has been condensed on the nanoparticle surface by a hydrolytic condensation reaction in addition to the quasi-monolayer type small molecular surface modification. It was expected that this additional modification will lead to more intensive cross-linking in coating systems resulting in further improved scratch-resistance compared to simple addition of nanoparticles with quasi-monolayer surface modification. The resulting compositions have been coated on zinc-galvanized steel and cured. The wear resistance and the corrosion protection of the modified coating systems have been tested in dependence on the compositional change, the type of surface modification as well as the mixing conditions with different shear forces. It has been found out that for loading levels up to 50 wt.-% nanoparticles, the mechanical wear resistance remains almost unaffected compared to the unmodified resin. In addition, the corrosion resistance remained unaffected even after $180^{\circ}$ bending test showing that the flexibility of coating was not decreased by nanoparticle addition. Electron microscopy showed that the inorganic nanoparticles do not penetrate into the organic resin droplets during the mixing process but rather formed agglomerates outside the polymer droplet phase resulting in quite moderate cross linking while curing, because of viscosity. The proposed mechanisms of composite formation and cross linking could explain the poor effect regarding improvement of mechanical wear resistance and help to set up new synthesis strategies for improved nanocomposite morphologies, which should provide increased wear resistance.