• Preventive Nutrition and Food Science
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• v.16 no.4
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• pp.364-369
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• 2011

Levels of carbon dioxide gas, a metabolite of microbial growth, have been reported to parallel the onset of microbial spoilage and may be used as a convenient index for a packaged food's shelf life. This study aimed to establish a kinetic model of $CO_2$ production from perishable food for the potential use for shelf life control in the food supply chain. Aerobic bacterial count and package $CO_2$ concentration were measured during the storage of seasoned pork meat at four temperatures (0, 5, 10 and $15^{\circ}C$), and their interrelationship was investigated to establish a mathematical model. The microbial growth at constant temperature was described by using model of Baranyi and Roberts. $CO_2$ production from the stored food could be explained by taking care of its yield and maintenance factors linked to the microbial growth. By establishing the temperature dependence of the microbial growth and $CO_2$ yield factor, $CO_2$ partial pressure or concentration in package headspace could be estimated to a limited extent, which is helpful for controlling the shelf life under constant and dynamic temperature conditions. Application and efficacy of the model needs to be improved with further refinement in the model.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.400-406
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• 2015

This study researched the structure of the source of an ion milling machine used to fabricate a scanning electron microscope (SEM) sample. An ion source is used to mill out samples of over 1 mm dimension using a broad ion beam to generate plasma between the anode and cathode using a permanent magnet. To mill the sample in the vacuum chamber, the ion source should be greater than 6 kV for a positive ion current over $200{\mu}A$. To discover the optimum operating conditions for the ion miller, the diameter of the extractor, anode shape, and strength of the permanent magnet were varied in the experiments. A silicon wafer was used as the sample. The sputter yield was measured on the milled surface, which was analyzed using the SEM. The wafer was milled by injecting 1 sccm of argon gas into the 0.5 mTorr vacuum chamber.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.608-613
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• 1993

Production of cyclodextrin (CD) by cyclodextrin glycosyltransferase (CGTase) isolated from alkalophilic Bacillus sp. was carried out to determine optimal reaction conditions. The maximum initial rate of CD production from amylose was obtained at dextrose equivalent 10.5. The CD production yield showed inverse proportionality to DE values over the range from 0.5 to 37.7. Even though the deactivation constant of CGTase at $60^{\circ}C$ was higher than those at lower temperatures, the production rate and yield at $60^{\circ}C$ were still higher. These results suggest thermal stabilization of CGTase by binding with starch.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2227-2232
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• 2011

The new metrology, Advanced Poly-silicon Ultra-Trace Profiling (APUTP), was developed for measuring bulk Cu and Ni in heavily boron-doped silicon wafers. A Ni recovery yield of 98.8% and a Cu recovery yield of 96.0% were achieved by optimizing the vapor phase etching and the wafer surface scanning conditions, following capture of Cu and Ni by the poly-silicon layer. A lower limit of detection (LOD) than previous techniques could be achieved using the mixture vapor etching method. This method can be used to indicate the amount of Cu and Ni resulting from bulk contamination in heavily boron-doped silicon wafers during wafer manufacturing. It was found that a higher degree of bulk Ni contamination arose during alkaline etching of heavily boron-doped silicon wafers compared with lightly boron-doped silicon wafers. In addition, it was proven that bulk Cu contamination was easily introduced in the heavily boron-doped silicon wafer by polishing the wafer with a slurry containing Cu in the presence of amine additives.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.302-310
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• 1990

A study has been made of the Korean bentonite aqueous suspension contrast with American bentonite by means of XRD IR swelling, gel formation and rheogram at various conditions such as concentration, temperature and pH. The Korean bentonite was identified as montmorillonite clay containig a small proprotion of crystoballite and mordenite, and its swelling power were acceptable for requirements of Korean pharmacopeia regulations though its values were not satisfied. Korean bentonite swelled to 10 times and American one did to 15 times compared to its bulkiness of powder. The rheogram of Korean bentonite suspension reveals bulged pseudoplatic flow with yield value at higher concentration and pseudoplastic flow without yield value at lower concentration. The higher the concentration, the greater were the apparent viscosity and hysteresis loop. Korean bentonite suspension showed insignificant temperature dependence on both apparent viscosity and hysteresis loop and it was more temperature dependent on viscosity but less on hysteresis loop than those of American sample. The pH dependence was so high on viscosity that apparent minimum value was near pH 7 and maximum value at pH 3 or 7. The hysteresis loop appeared minimum over the pH range 5-7 and maximum near pH 3 or 11. The Korean bentonite was inferior to the American bentonite in swelling volume, gel formation, thioxotropy, however, it would be possible to improve the quality of Korean bentonite by developing the method of purification for bentonite clay.

• Journal of the Korean Society of Tobacco Science
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• v.14 no.1
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• pp.3-11
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• 1992

The present study examined various environmental and cultural media conditions for in vitro "rescue" of cross-fertilized ovules formed through sexual crosses between Nicotiana rustica and N. tabacum cv. BY4. The response ovules to two cultural procedures was compared; ovules were cultured either separately or left attached to the placenta. Total yield of seedlings and percent of normal seedlings were increased by culturing individual ovules separately, rather than on excised placenta. Total yield of seedlings and number of normal seedlings were produced following in vitro culture of individual fertilized ovules of N. rustica X M tabacum cv. BY4 at four days post-pollination on NN medium containing 2% sucrose. In the in vitro culture of fertilized ovules, high sucrose concentration increased the frequency of seedlings of abnormal appearance. Therefore, sucrose should be supplied to developing ovules at gradually decreased concentrations. Culture of fertilized ovules from three to eight days after pollination gave increased number of seedlings, but with delayed cultral time the number of morphologically normal seedling were decreased. Hybrids were uniform in appearance and showed vegetative heterosis but flower characteristics were generally intermediate between those of the parents. All hvbrids evaluated were self-sterile.f-sterile.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.177-186
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• 1971

In order to obtain an idea on the cause of beneficial effect of organic matter, compost and fresh rice straw, in paddy production, a number of previous experimental results were reviewed. The results are as follows: 1. As a soil ameriolater, compost give a beneficial effect, in well drained and somewhat permeable soils but in ill drained and none permeable paddy field the effect is not observed. 2. The effect of fresh rice straw, is expected to be positive with less than compost limitation to the soil conditions. The reason for this benefical effect of fresh rice straw to paddy yield is evidenced to be of depressing effect of early stages of paddy growth which reserves plant nutrients in soil for later use. 3. Several problems in connection with the use of fresh rice straw in rice production is also discussed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.85-90
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• 2005

A downstream process was developed for the production of yeast extract from brewer's yeast cells. Various downstream processing conditions including clarification, debittering, and the Maillard reaction were considered in the development of the process. This simple and economic clarification process used flocculating agents, specifically calcium chloride ($1\%$). After the clarification step, a Maillard reaction is initiated as a flavor-enhancing step. By investigating the effects of several operation parameters, including the type of sugar added, sugar dosage, glycine addition, and temperature, on the degree of browning (DB), giucose addition and reaction temperature were found to have significant effects on DB. A synthetic adsorption resin (HP20) was used for the debittering process, which induced a compositional change of the hydrophobic amino acids in the yeast hydrolysate, thereby reducing the bitter taste. The overall dry matter yield and protein yield for the entire process, including the downstream process proposed for the production of brewer's yeast extract were 50 and $50\%$, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.3
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• pp.247-252
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• 1990

Nine Holstein cows in mid lactation period were utilized to examine the effect of recombinant bovine somatotropin (BST) of tow companies (Company A, Company B) on milk production and milk composition under the feeding conditions of Korea. Treatments were 0 (Control), 25 mg BST/day from company A (BST A) and 25 mg BST/day from company B (BST B) injected subcutaneously, once daily beginning at $200{\pm}20$ days postpartum and continuing for 28 days. Cows were fed ad libitum a total mixed diet throughout the experimental period. BST treatments increased average 4% fat corrected milk yields and milk energy output over the 28-day treatment period. However, no differences were observed in dry matter intake, gross efficiency, energy intake and percent milk energy. Although there was a tendency for increased milk fat percent, there were no differences in milk composition and yields of major milk components except for milk fat yield with BST injection. Somatic cells of all groups were also characteristic of a well managed herd. Neither mean body condition score nor body weight was significantly (p <0.05) changed before and during BST treatment. BST concentration in milk remained in the range of control animals throughout the experimental period of BST treatment. Results indicate that short-term injection of recombinant bovine somatotropin from two companies to lactating dairy cow resulted in similar increased in milk yield without alteration of major milk components or feed intake.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.369-375
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• 1991

A series of in vitro incubation studies with washed rumen bacteria were conducted to determine the influence of incubation time and concentrations of peptides, alanine, ammonia nitrogen and carbohydrate on the rate of peptide disappearance and on bacterial growth. Disappearance rate of tri-alanine (ala3) under various conditions was between 30.6 and $58.2mg\;hr^-$ per gram bacterial dry matter. Ala3 was removed from the incubation medium in an almost linear fashion as incubation time and ala3 concentration was increased. Washed rumen bacteria utilized ala3 faster than di-l-alanine (ala2) at all concentrations. Adding 9mM carbohydrate significantly increased ala3 disappearance, but level of ammonia nitrogen had no influence on ala3 disappearance. The presence of alanine in the medium significantly lowered ala3 utilization by rumen bacteria. Bacterial dry matter and nitrogen growth yield were not influenced by alanine and peptides when incubation medium already contained a sufficient level of ammonia nitrogen. Increased ammonia nitrogen in the presence of ala3 did not stimulate bacterial growth. Carbohydrate significantly increased bacterial dry matter and nitrogen growth as expected. Results indicate that the rate of peptide utilization by rumen bacteria may be altered by type and concentration of peptides, and energy supply, and this may be mediated through changes in numbers and type of bacteria.