• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.2
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• pp.205-214
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• 1999

The objective of this paper is to investigate the thermal properties of TMA clathrate compound applicable to cold storage system for building air-conditioning. Especially, the test tube experiments are performed by comparing and analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of density, temperature of heat source and charging quantity in TMA clathrate compound. The results are summarized as follows:1) $-15^{\circ}C$ is not proper as the temperature of heat source because the temperature of subcooling is above $8.3^{\circ}C$ 2) temperature of phase change is dropped as the temperature of heat source is lower, 3) the effect of subcooling suppression with about 8$^{\circ}C$ is confirmed when the temperature of heat source is $-10^{\circ}C$ in case of 26, 27, and 30wt%, while the temperature of subcooling is about $0^{\circ}C$ when the temperature of heat source is $-15^{\circ}C$ in case of 25, 26 and 30wt%. Thus, the effect of subcooling suppression is greater as the temperature of heat source is lower. Additionally, the concentrative study is needed on mass concentration causing the phase change without subcooling phenomenon when the temperature of heat source is $-15^{\circ}C$. Thus, it is concluded that TMA clathrate compound has enough thermal properties as the cold storage medium for building air-conditioning.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.725-734
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• 2000

The objective of this paper is to investigate the thermal properties of TMA clathrate applicable to cold storage system for building air-conditioning. Especially, the test tube experiments are peformed by comparing and analyzing the temperature of phase change, specific heat and subcooling characteristic according to the variation of concentrations and temperature of heat source in TMA clathrate. The results are summarized as follows; 1) temperature of phase change is dropped as the temperature of heat source is lower, 2) the effect of subcooling suppression with about $9.3^{\circ}C$ is confirmed when the temperature of heat source is $-10^{\circ}C$ in case of 30wt%, while the temperature of subcooling is about $0^{\circ}C$ when the temperature of heat source is $-15^{\circ}C$ in case of 25, 29wt% and 30wt% . Thus, the effect of subcooling suppression is greater as the temperature of heat source is lower. Additionally, the concentrative study is needed on mass concentration causing the phase change without subcooling phenomenon when the temperature of heat source is $-15^{\circ}C$ Thus, it is concluded that TMA clathrate has proper properties as the cold storage medium for building air-conditioning.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3579-3582
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• 2010

We studied the reaction of tri-methylaluminum (TMA) on hydroxyl (OH)-terminated Si (001) surfaces for the initial growth of aluminum oxide thin-films using density functional theory. TMA was adsorbed on the oxygen atom of OH due to the oxygen atom’s lone pair electrons. The adsorbed TMA reacted with the hydrogen atom of OH to produce a di-methylaluminum group (DMA) and methane with an energy barrier of 0.50 eV. Low energy barriers in the range of 0 - 0.11 eV were required for DMA migration to the inter-dimer, intra-dimer, and inter-row sites on the surface. A unimethylaluminum group (UMA) was generated at each site with low energy barriers in the range of 0.21 - 0.25 eV. Among the three sites, the inter-dimer site was the most probable for UMA formation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.293-299
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• 2004

In this paper, thermal and mechanical properties of electric epoxy with water aging were discussed. We made elastic epoxy specimen adding a ratio of 0〔phr〕20〔phr〕, 35〔phr〕 and 53〔phr〕 with modifier to existing epoxy. We studied mechanical property of elastic resin after absorption in water from 0 to 484 hours. As a result, diffusion factor of elastic epoxy showed 20-21${\times}$10$^{-4}$ $\textrm{mm}^2$/s and general epoxy showed 9.5${\times}$10$^{-4}$ $\textrm{mm}^2$/s. Elastic property increased linearly according to addiction and decreased according to water absorption. Tensile strength was reduced according to addition. It was affected by water absorption of micro-void of elastic epoxy. Hardness inclined to decrease after increasing according to absorbed time. In water-absorption state, it was experimented a change of heat flow by temperature of elastic epoxy and change of thermal expansion coefficient. DSC (Differential Scanning Calorimetry) and TMA (Thermomechanical Analysis) equipments were used to measure Tg. A temperature ringe of DSC was from -0($^{\circ}C$) to 200($^{\circ}C$). One of TMA was from -0($^{\circ}C$) to 350($^{\circ}C$). In addition, we investigated structural analysis of water absorbed specimen using SEM (Scanning Electron Microscope).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.192-199
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• 2004

Elastic-factor of elastic epoxy were investigated by TMA (Thermomechanical Analysis), DMTA (Dynamic Mechanical Thermal Analysis), TGA (Thermogravimetric Analysis) and FESEM (Field Emission Scanning Electron Microscope) for structure-images analysis as toughness-investigation to improve brittleness of existing epoxy resin. A range of measurement temperature of the TMA and DMTA was changed from -20($^{\circ}C$) to $200^{\circ}(C)$, and TGA was changed from $0^{\circ}(C)$ to $600^{\circ}(C)$. Glass transition temperature (Tg) of elastic epoxy was measured through thermal analysis devices with the content of 0(phr), 20(phr) and 35(phr). Also, thermal expansion coefficient (a), high temperature, modulus and loss factor were investigated through TMA, TGA, and DMTA. In addition, the structure of specimens was analyzed through FESEM, and then elastic-factor of elastic epoxy was visually showed by FESEM. As thermal analysis results, 20(phr) was more excellent than 30(phr) thermally and mechanically. Specially, thermal expansion coefficient, high temperature, modulus, and damping properties were excellent. By structure-images analysis through FESEM, we found elastic-factor of elastic epoxy that is not existing epoxy, and proved high impact.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.183-184
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• 2005

In this paper. a new small size Lateral Trench Electrode Power IGBT is proposed. The entire electrode of proposed LIGBT is placed in trench oxide. The forward blocking voltage of the proposed LIGBT is improved by 1.6 times with that of the conventional LIGBT. The forward blocking voltage of proposed LIGBT is 500V. At the same size. a increase of the forward blocking voltage of about 1.6 times relative to the conventional LIGBT is observed by using TMA-MEDICI which is used for analyzing device characteristics. Because the electrodes of the proposed device are formed in trench oxide. the electric field in the device are crowded to trench oxide. We observed that the characteristics of i the proposed device was improved by using TMA-MEDICI and that the fabrication of the proposed device is possible by using TMA-TSUPREM4.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.3
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• pp.320-331
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• 2019

In this paper, we propose a method of TMA(Target Motion Analysis) performance improvement using target elevation tracking and fusion in conformal array sonar. One of the most important characteristics of conformal array sonar is to detect a target elevation by a vertical beam. It is possible to get a target range to maximize advantages of the proposed TMA technology using this characteristic. And the proposed techniques include target tracking, target fusion, calculation of target range by multipath as well as TMA. A simulation study demonstrates the outstanding performance of proposed techniques.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1337-1342
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• 2004

To improve the quality of Gulbi, 10% garlic juice (GJ), 10% onion juice (OJ), and 10% garlic and onion juice mixture (GOJ) were added to the brine solution as a wet-salting method. The changes of total volatile basic nitrogen (TVB-N) and trimethyl amine (TMA) production, thiobarbituric acid reactive substance (TBARS) value, and total microbial numbers in Gulbi were analyzed during storage at room temperature for 12 days. The group treated with 10% GOJ showed the lowest values of 88.2 mg/l00 g in TVB-N, 14.13 mg/l00 g in TMA, and 3.1 $\mu$mol/kg in TBARS. The fatty acid profile of Gulbi was analyzed on 5, 15, and 30 days to investigate the effect of GOJ treatment. The group treated with GOJ showed higher C22:6 (9.91%) and C20:5 (4.25%) contents than control (7.37% and 3.71%, respectively), but had lower C18:1 (24.44%) content. The saturated fatty acid content in Gulbi was 32∼35% and the C16:0 (21∼23%) was predominant in it. Oleic acid was major unsaturated fatty acid in Gulbi. The contents of polyunsaturated fatty acids (C18:3, C20:5, C22:6) were decreased after 30 days but increased the saturated fatty acid (C16:0) and monoenes (C16:1 and C18:1). The Gulbi treated with GOJ by brine salting method showed higher DHA and EPA (9.91% and 4.25%, respectively) contents than the control group.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.344-352
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• 1984

In recent years, the occurrence of nitrosamine, which are produced by the interaction of nitrite and secondary amine, in foods has been the subject of considerable interest and controversy. In this experiment, changes in nitrate, nitrite, TMAO, TMA and DMA nitrogen of salted and dried corvenia, which were incorporated with sodium benzoate, ascorbic acid, cysteine and tetracycline in salt, during processing and storage were analyzed. Levels of nitrate nitrogen was decreased while those of nitrite was increased in salted and dried products during processing and storage, but sample was incorporated with ascorbic acid, cysteine and sodium benzoate in salt inhibited the reduction of nitrate to nitrite while with tetracycline in salt accelerated this reduction in salted and dried products during processing and storage. Contents of TMAO nitrogen in all salted and dried products as well as in the control was decreased, but was increased during storage, while TMA nitrogen was increased in salted and dried products during processing and storage. Contents of DMA nitrogen was increased in all salted and dried products during processing and storage, DMA contents of raw in the control was increased to more than 11.6 times after storage for 30 days, but sample was incorporated with ascorbic acid, cysteine and sodium benzoate in salt inhibited the production of DMA nitrogen while with tetracycline in salt accelerated in salted and dried products during processing and storage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.7-14
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• 1981

Secondary amines are known as one of the precursors of nitrosamines which are potent carcinogenic compounds for human being and animals. In this study, trimethylamine and dimethylamine contents of salted, hot-air dried and sun dried samples of two commercial fishes, mackerel pike and seerfish were analyzed and quantitatively compared at three different temperature conditions. The formation of both secondary amines was more rapid at$10^{\circ}C\;and\;15^{\circ}C\;than\;at\;2^{\circ}C$. Residual amounts of trimethylamine oxide of salted samples were relatively higher than those of the other samples. Trimethylamine contents of hot-air dried mackerel pike and sun dried seerfish were relatively higher than those in the other samples, while those of salted samples were comparatively lower than those of others. Dimethylamine contents of hot-air dried samples were higher than those of the other samples, whereas those of salted samples were comparatively lower than those of the other samples.