• Korean journal of food and cookery science
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• v.11 no.3
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• pp.249-260
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• 1995

6 Central commissary and 2 conventional school foodservice operations were assessed in terms of time-temperature relationship and microbiological quality, and monitoring control methods were identified through hazard analysis during the phases of prodution and distribution. 2 conventional schools from Seoul and 6 commissary schools from Kyungkido were participated in the survey. Meals produced in central commissary were distributed to satellites, therefore delivery practices of foods were identified as critical. Microbiological test results for commissary and conventional schools revealed that microbiological quality of foods was mainly related to time-temperature management, types of food, and equipment sanitation not to the foodservice system used. Time-temperature profiles at temperature danger zone (7.2-60$^{\circ}C$) observed were to be related to the following sanitary practices: cooked vegetables were held at temperature danger zone for relatively longer delayed time (15-38$^{\circ}C$: 15-226 min, 7-60$^{\circ}C$: 75-226 min), and same results were observed for deep-fat fried cutlets (15-38$^{\circ}C$: 15-151 min, 7-60$^{\circ}C$: 33-151 min). Menu items with various ingredients and frequent contacts with hands and equipments during the production flow were held at temperature danger zone for longer delaying time than other menu items with brief prodution stages. Based on hazard analysis critical control points, microbiological quality was collectively affected by time-temperature relationships, equipment sanitation, proper cooking methods, and sanitary management competencies of dietitians. Microbiological test results of working equipments and surface of dishes and trays showed that immediate action should be taken. Cutting boards used in central kitchen were also showed similar results of potential dager of cross-contamination. Effective sanitary control methods were urgently needed.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.268-275
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• 2004

To investigate the potential application of the single-cell gel electrophoresis (SCGE) assay to carp as an aquatic pollution monitoring technique, gill, liver, and blood cells were isolated from carp exposed to a direct-acting mutagen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), or indirect mutagen, $benzo[\alpha]pyrene$ $(B[\alpha]P)$, then the DNA strand breakage was analyzed using the assay. Based on testing 5 different cell isolation methods and 6 electrophoretic conditions, the optimized assay conditions were found to be cell isolation by filter pressing and electrophoresis at a lower voltage and longer running time (at 0.4 V/cm for 40 min). In preliminary experiments, gill and liver cells isolated from carp exposed to MNNG in vitro exhibited DNA damage signals even with 0.5 ppb exposure, which is a much higher dose than previously reported. In the gill cells isolated from carp exposed to 0.01-0.5 ppm MNNG in vivo, significant dose-and time-dependent increases were observed in the tail for 4 days. As such, the linear correlation between the relative damage index (RDI) values and time for each dose based on the initial 48-h exposure appeared to provide effective criteria for the genotoxicity monitoring of direct-acting mutagenic pollution. In contrast, the in vivo exposure of carp to 0.25-1.0 ppm of $B[\alpha]P$ for 7 days resulted in dose-and time-dependent responses in the liver cells, in which 24-h delayed responses for metabolizing activation and gradual repair after 48 h were also observed. Thus, the negative-sloped linear correlation between the RDI and time at each dose based on the initial 48 h appeared to provide more effective criteria for the genotoxicity monitoring of indirect mutagenic pollution.

• Biomolecules & Therapeutics
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• v.4 no.4
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• pp.391-397
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• 1996

The aim of this study was to assess the allergenic potential of 0.3% DA-5018 cream, a non-narcotic analgesic agent, using a guinea pig maximization test. Five male and female guinea pigs in the experimental group were sensitized in two steps. First, ,0.3% DA-5018 cream was injected intradermally, and 7 days later, the material was applied topically. After another 2 weeks test material was applied, the skin response was evaluated by visual observation. Five male and female guinea pigs served as cream base group, negative(ultreated) group or positive (2,4-dinitrochlorobenzene, DNCB) group, respectively. 0.3% DA-5018 cream provoked slight erythema in 1 out of 5 cases in male and female guinea pigs sensitized with 0.3% DA-5018 cream or cream base. The animals challenged with cream base also showed slight erythema in 1/5 female guinea pig sensitized with 0.3% 3A-5018 cream or 2/5 male guinea pjgs sensitized with cream base, respectively. Histologically, however, no indication of skin sensitization was observed in all of these cases. The positive control group was sensitized with 0.1% DNCB suspended in olive oil and challenged with 0.01% and 0.1% DNCB ointment, all the animal showed remarkable skin reactions and obvious skin sensitization reactions in a dose dependent manner. From the challenge test it was evident that 0.3% DA-5018 cream did not elicit positive skin reaction interpreted as delayed hypersensitivity reactions, compared with cream base or untreated control group. These findings indicate that allergenic side effects by 0.3% DA-5018 cream is not likely in the clinical use.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.106-112
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• 1989

To investigate varietal differences of anther size, pollen shape, pollen fertility and other agronomic characters under low temperature condition. twenty rice varieties (5 Tongil and 15 Japonica type) were treated at 19$^{\circ}C$ water temperature from booting to heading stage. There was varietal difference of low temperature response which was indicated by the delayed heading, the shortening of culm and panicle length. and the decrease of grain fertility and yield potential resulted from cooling treatment at booting stage. The varieties with low fertility damaged by the low temperature treatment at booting stage showed low pollen density per anther. small or abnormal anthers and pollen, and many sterile pollens. Anther length was correlated significantly with the number of pollens per anther and pollen fertility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1100-1112
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• 1998

In this paper, a novel method of minimizing the phase error is proposed. A DP-PLL system using this method is implemented and its performacnce is investigated, too. The DP-PLL system detects the phase error between reference clock and locally generated system clock. The phase difference is then reported as a PEV(Phase Error Variation), which is propoced from the delayted n-tap rising dege clock circuit with 5ns resolution in the phase detector. The algorithm is used to track the optimal DAC coefficients, which are adjusted from sample to sample in such a way as to minimize the PEV. The proposed method is found to have remarkable good potential for fast and accurate phase error tracking characteristic. The algorithm shows good performance to supress the low frequency jitter.-ending points, we design new basis functions based on the Legendre polynomial and then transform the error signals with them. When applied to synthetic images such as circles, ellipses and etc., the proposed method provides, in overall, outstanding results in respect to the transform coding gain compared with DCT and DST. And in the case when applied to natural images, the proposed method gives better image quality over DCT and comparable results with DST.

• Food Science and Preservation
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• v.23 no.1
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• pp.7-11
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• 2016

In order to develop a sprayable ethylene antagonist, unlike 1-methylcyclopropene (MCP), we synthesized 2-decylcyclopropene-1-carboxylic acid ethyl ester (DCPE) as a derivative of cyclopropene and tested its effect on the flesh softening of 'Fuyu' persimmon fruits. The fruits on trees were sprayed with $4{\cdot}10^{-4}$ M DCPE solution before harvest. After harvest, the persimmon fruits were stored at a low temperature for 1.5 months. The ripening progress of the fruits was then evaluated during storage at ambient temperature ($20^{\circ}C$). Flesh softening, a measure of ethylene response, was considerably delayed up to 7 days after DCPE treatment. However control fruits was rapidly softened after 3-day storage. The treatment effect of DCPE at $4{\cdot}10^{-4}$ M was also compared to that of 1-MCP at 1 ppm. DCPE was storable at refrigerated conditions for at least one month without any loss. The results show that DCPE could be a potential sprayable agent for the prevention of flesh softening of persimmon fruit.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.386-396
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• 2001

Mixtures Of AUC-UO$_2$and Gd$_2$O$_3$ Powders doped With Cr$_2$O$_3$ or Cr$_2$O$_3$-SiO$_2$ were Pressed and sintered at 1730 t in hydrogen gas witk various water-vapor contents. The density of UO$_2$- 6wt% Gd$_2$O$_3$ pellets can be increased from 91% TD to 94.5% TD in 1 vol% $H_2O$-H$_2$ gases by the addition of 0.02wt% Cr$_2$O$_3$-(0.01~0.04) wt% SiO$_2$. The magnitude of density increase is much larger in (1~3 vol%) $H_2O$-H$_2$ gases than in 0.05 vol% $H_2O$-H$_2$ gas. The densification of U0$_2$- Gd$_2$O$_3$ compact is significantly delayed in the temperature range between 1300 and 1500 t , but that of compacts with Cr$_2$O$_3$-SiO$_2$ is not. The role of Cr$_2$O$_3$ and SiO$_2$ in densification is discussed.

• Polymer(Korea)
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• v.37 no.5
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• pp.553-556
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• 2013

Chlorine dioxide gas has an excellent ability for sterilization and deodorization, and is harmless to humans. However, it is very unstable and explosive as it is highly concentrated, thus its use in the air clean fields has been limited. Therefore, there is need to control chlorine dioxide gas at a low concentration for a long time. Chlorine dioxide gas could be produced slowly and sustainedly since the release of acetic acid from the polymer hydrogels delayed the reaction between acetic acid and sodium chlorite. In addition, as the amount of both acetic acid sodium chlorite loaded within the hydrogel and on the membrane increased, respectively, the generation amount of chlorine dioxide gas increased. The result shows that the use of polymer hydrogels has the potential to control the generation of chlorine dioxide gas.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.795-804
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• 1997

Developmental dental morphological anomalies are fusion, gemination, twinning, concrescence and etc. They may cause many problems in conservative, periodontal and esthetic aspects. Fusion is a condition where two separate tooth buds unite at some stage in their development to form a bifid crown. If tooth contact occurs early, at least before the start of calcification, the two teeth may be completely unites to form a single large tooth. If tooth contact occurs after the time when a portion of the tooth crown has completed its formation, there may be union of the roots only. In fusion the dentin is always confluent. Fusion teeth is more common in the deciduous than in the permanent dentition. Fused teeth are relatively rare, and are mostly mandibular anterior teeth. Fusion of normal and supernumerary teeth or between normal teeth may occurs. The exact etiology factor of fusion is unknown, but genetic and environmental factors seems to be related. A variety of complications and subsequent treatments have been suggested on this teeth. Periodontal conditions may arise due to a groove formed at the line of fusion of the two teeth. Crowding or Protrusion with potential for malocclusion or delayed eruption of adjacent teeth. Fusion teeth appear in the anterior region, they usually cause esthetic problems. Treatments vary depending on the problem, the location, and the extent of fusion. Treatment of fused teeth has been reported from endodontic, orthodontic, periodontic, surgical and multidisciplinary. This report presents the esthetic improvements by separation of two clinical crowns. Bone reduction or endodontic treatments are not required.

• Journal of the Korean Chemical Society
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• v.40 no.9
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• pp.640-648
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• 1996

Crosslinked chitosan was prepared from chitin after reaction with epichlorohydrin followed by deacetylation at C2-position. Epidermal releasing polymeric matrix was prepared after swelling crosslinked chitosan with distilled water and adding silver sulfadiazine and glycerine as a plasticiser. The release behavior of silver sulfadiazine from polymeric matrix was studied in pH 7.4 phosphate buffer solution by varing the drug content, glycerine concentration, and the thickness of the matrix. The drug release time was delayed by increasing the content of silver sulfadiazine and the thickness of the matrix, whereas decreased as glycerine concentration increased. The apparent constant(K) of release rate was independent upon the matrix thickness, but was proportional to the content of drug or glycerine of crosslinked chitosan matrix. These results indicated that chitosan matrix showed some potential as a drug delivery system for transdermal therapeutic application.