• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.884-888
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• 1998

Effects of heating time under high temperature on the thermal and mechanical properties of neutron shielding materials based on modified (KNS-102), hydrogenated(KNS-106) bisphenol-A type epoxy resin and phenol-novolac(KNS-611) type epoxy resin for radioactive material shipping casks have been investigated. At early stages, the initial decomposition temperatures of the shielding materials of KNS-102, KNS-106 and KNS-611 increased with the heating time under high temperature, but it was rarely affected by the heating time in the later stages. In addition, the thermal conductivities of KNS-102 and KNS-106 decreased with heating time, but that of KNS-611 increased with the heating time. On the contrary, the thermal expansion coefficients of neutron shielding materials decreased with increase of heating time. At the high temperature, the tensile strength and flexural strength of the shielding materials of KNS-102 and KNS-611 increased with heating time, but those of KNS-106 decreased with increase of heating time. And the heating time under high temperature on the neutron shielding materials did not show measurable loss of weight and hydrogen content.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.24-34
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• 2001

The authors reconstruct a mooring type underwater positioning system to measure the movement of bag-net in a set-net by long base line mode with four transponders attached on the bag-net in latitudinal and a transponder fixed on the sea bed. To confirm the practical use of the system, the field experiments were carried out at the Jaran Bay, Kosung, Kyungnam Prov., on October 6, 2000 (neap tide) and November 28, 2000 (spring tide). And the vertical oscillation of bag-net was observed with three data loggers attached on the bottom of bag-net in longitudinal on November 28, 2000. The longitudinal movement range, the latitudinal one and the vertical one of the bag-net were 3.2 m, 3.4 m and 2.1 m. respectively. At the spring tide, these variations were 7.8 m, 7.8 m and 5.0 m, respectively. The vertical oscillation range about the bottom of the bag-net at near point of the slope net, at the middle part and at far point from the slope net were 3.2 m, 3.7 m and 8.4 m, respectively. The depth of the bottom net was decreased and its vertical oscillation appeared frequently when the current speed was more than 10 cm/s and the current direction was significantly different from the longitudinal axis of the bag-net. The variation of hydrophone coordinates measured by the transponder fixed on the sea bed presents that hydrophones equipped to the frame line of the set-net could be moved within several meters due to the tidal current. The fact indicates that the compensation of hydrophone coordinates is necessary to reduce the measuring errors. The position measuring errors of x, y and z axis of the system measured in the cage of aquaculture were 0.6 m, 0.8 m, and 1.2 m, respectively. And the errors of the transponders those were close to the base lines or placed in the baselines were smaller than those of others.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.346-357
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• 2013

In this study, it was conducted to produce wood pellets using domestic forest thinning residues and examine their quality according to Korean pellet quality standard. Raw materials were composed of larch and mixed broad leaves species. Based on the small-end diameter (6 cm), they were classified into four different types of raw materials such as LM (larch with middle diameter), LS (larch with small diameter), MM (mixed broadleaf with middle diameter), and MS (mixed broadleaf with small diameter). After crushing and drying process, wood pellets were produced by a ring-die type pelletizer using each raw material. Wood pellets made from four different types of raw materials were tested for their quality such as calorific value, moisture content, ash content, inorganic matters and so on. As results of quality analysis, the calorific values of all wood pellets were higher than 198 kcal/kg, and satisfied with the first grade of Korea wood pellet standard. The ash content was slightly increased after pelletizing. Mechanical durability of wood pellets was highly dependent on the types of raw materials. The quality differences among wood pellets were turned out due to different physical and chemical characteristics of raw materials even though the same pelletizing condition was applied.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.46-51
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• 2018

Hydrogen sulfide from landfill and sewage treatment plant is a major odor component and causes many civil petitions. Rapidly developing industries release hydrogen sulfide, an odorous gas, to the atmosphere. This study aims to develop a $10{\mu}mol/mol$ concentration level hydrogen sulfide primary standard gas for odor measurement. The hydrogen sulfide gas was prepared at a nominal concentration of $10{\mu}mol/mol$ in nitrogen using the gravimetric method described in ISO 6142. Replicate standard gases were produced in 4 aluminium cylinders, and their concentrations were verified by GC-AED. The uncertainty of production was less than 0.50 %, and the variation of the 4 replicates was 0.22 %. The wall adsorption of hydrogen sulfide in cylinders was 0.10 % at 1500 psi, and the concentration was estimated to be long-term stable for one year. The relative expanded uncertainty of the preparation consistency, adsorption and long-term stability of this hydrogen sulfide standard gas was less than 1.05 % (95 % of confidence level, k=2).

• Journal of Sensor Science and Technology
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• v.7 no.2
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• pp.111-116
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• 1998

The simple solid electrolyte carbon dioxide sensor with heaters were fabricated by using Li ionic conductor. Two Au electrodes were used for the reference and sensing electrode respectively. Two types of gas sensors, type ( I ) and type (II), were fabricated. Type ( I ) sensor was fabricated by the method of melting and crystallizing alkali metal carbonate at the temperature of $420{\sim}500^{\circ}C$. The sensing membrane of type (II) sensor was formed by the printing method on sensing electrode after metal carbonate was mixed with binder. The response characteristics of sensors fabricated for the carbon dioxide were investigated for a range of $CO_{2}$ concentration from 950 ppm to 9,950 ppm at operating temperature $420^{\circ}C$. Type ( I ) sensor and type (II) sensor showed the sensitivity of 62 mV/decade and 65 mV/decade respectively. The emf/decade of type (II) sensor tested at $420^{\circ}C$ almost followed the theoretical value of Nernst's equation and showed stable response characteristics with the fast response time of $15{\sim}20$ sec. Also type (II) sensor showed excellent stability and reproduction properties for 60 days.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.1
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• pp.1-6
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• 2018

This study was conducted to investigate the feed value and silage quality according to storage period and film layers in whole crop oat silage. The crude protein content was increased in all silage during the storage periods compared to those before silage, under prolonged storage period slightly and the number of film layers of silage, six layer were higher than four layers, but no significant. NDF and ADF contents were also increased in all silage of storage duration compared to those before silage, but they was similar level between storage duration and number of film layers. TDN content was decreased of the storage duration. However, it was similar under the storage duration and the number of film layers. The pH value was decreased during prolonged storage period and six layers was lower than four layers depending on the film layers. In the organic acid contents, lactic acid and acetic acid were increased under the prolonged storage duration, and butyric acid was higher significantly(p<0.05), six layers of the film were showed higher lactic acid and lower butyric acid(p<0.05). Therefore, oat silage should be used within 6 months it was when treated with 4 layers, if considering the long-term storage, it is desirable to treat it with 6 layers or more.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.39-48
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• 2020

Many studies have been conducted to analyze factors that affect customer satisfaction, and service quality improvement in the parcel delivery industry. Most of these studies have a limited number of respondents using methods such as surveys and interviews. Therefore, this study aims to supplement the shortcomings of previous studies, by searching and analyzing the common major topics related to the complaints pointed out by consumers and suppliers in the parcel delivery service with cases of consumer counseling, and articles that reflect the complaints of workers in the industry. In addition, by analyzing the trend of these topics, we attempted to discover new topics and suggest implications. In conclusion, topics such as delay/lost/wrong deliveries as well as the fierce competition in the parcel delivery industry, turned out to be central aspects. As a result of the topic trend analysis, talks with international couriers have recently increased, and many conflicts related to apartment parcel delivery have been dealt with. The topics presented in this study are mainly focused on the contents of previous studies, but we expect that new and valuable topics can be derived by adding other data and analysis methods, such as internal counseling and academic literature.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.1
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• pp.52-60
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• 2002

According as many people use a computer newly, damage of computer virus and hacking is rapidly increasing by the crucial users. A computer virus is one of program in computer and has abilities of self reproduction and destruction like a virus of biology. And hacking is to rob a person's data in a intruded computer and to delete data in a Person s computer from the outside. To block hacking that is intrusion of a person's computer and the computer virus that destroys data, a study for intrusion detection of system and virus detection using a biological immune system is in progress. In this paper, we make a model of positive and negative selection for self recognition which have a similar function like T-cytotoxic cell that plays an important role in biological immune system. We embody a self-nonself distinction algorithm in computer, which is an important part when we detect an infected data by computer virus and a modified data by intrusion from the outside. And we showed the validity and effectiveness of the proposed self recognition algorithm by computer simulation about various infected data obtained from the cell change and string change in the self file.

• Korean journal of applied entomology
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• v.50 no.4
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• pp.353-362
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• 2011

This study was conducted to elucidate the patterns of occurrence of bark beetles on deadwoods of Quercus serrata Fisher and Carpinus laxiflora Blume which are expected to increase due to climate change. The survey was carried out at the LTER site in Gwangneung forest in Gyeonggi Province in 2007-2008. Bark beetles were collected using emergence traps and attraction traps (funnel trap and window trap). A total of 408 beetles belonging to 12 species in two subfamilies were collected. Platypus koryoensis (Murayama) was the most abundant species. P. koryoensis and Xylosandrus germanus (Blandford) occurred mainly in deadwoods of Q. serrata. All other species, except two rare species, occurred commonly in deadwood of both tree species. Species richness and abundance of bark beetles were higher in the attraction traps than in the emergence traps, and higher in Q. serrata than in C. laxiflora. These indexes were higher in classes I-II or I-III than in classes III-IV or IV of deadwood. Bark beetle communities differed according to years and showed a little difference between tree species.

• Journal of agricultural medicine and community health
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• v.34 no.2
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• pp.244-255
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• 2009

Objectives: This study was to identify and test the health and nutritional status of grandparents in grandparents-grandchildren family in rural area. Methods: The subjects of this study were 70 grandparents of grandparents - grandchildren family in Muan-Gun. The collected data were analyzed by descriptive statistics, regression analysis. Results: The average age of grandparents was 70.1${\pm}$6.6 years old, unhealthy of the subjective health status was 55.7%, MNA score was 21.0${\pm}$3.5 points and 62.2% of the grandparents were shown to have malnutritonal status. The ADL, IADL, depression and fall index of health status were significantly related to the relationship with gender(p<.01), age(p<.05), economic(p<.01) and educational level(p<.01), and partnership(p<.01). MNA score was significantly related to the relationship with acute disease(p<.05), ADL(p<.001), IADL(p<.01), cognitive function(p<.01) and gender(p<.01). And the health status variables and general characteristics were positively correlated while the relationships were positive between health status variables and MNA score. Conclusions: With the above findings, grandparents of grandparents-grandchildren family have the problems of health and nutritional status. Then health and nutritional intervention program for grandparents-grandchildren family is needed to serve.