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김태범,안효준,허보영,Kim, T.B.,Ahn, H.Y.,Hur, H.Y. 한국재료학회 2006 한국재료학회지 Vol.16 No.3
The sodium/sulfur(Na/S) battery has many advantages such as high theoretical specific energy(760Wh/kg), and low material cost based on the abundance of electrode material in the earth. It has been reported that the electrochemical properties of sodium/sulfur cell above $300^{\circ}C$, utilized a solid ceramic electrolyte and liquid sodium and sulfur electrodes. A lot of researches have been performed in this field. Recently, Na/S battery system was applied for electricity storage system for load-leveling. One of severe problems of sodium/sulfur battery was high operating temperature above $300^{\circ}C$, which could induce the explosion and corrosion by molten sodium, sulfur and polysulfides. In order to develop sodium battery operated at low temperature, sodium ion battery has been studied using carbon anode, and sodium oxides cathodes. However, the energy densities of the sodium ion batteries were much lower than high temperature sodium/sulfur cell. In this study, the sodium/sulfur battery with 1M $NaCF_3SO_3$ is tested at room temperature. The charge-discharge mechanism was discussed based on XRD, DSC, SEM and EDS results.
케미칼 크랙킹 방법을 이용한 플라스틱 제품의 응력측정에 관한 연구
원시태 ( S. T. Won ),김태범 ( T. B. Kim ),이실 ( S. Lee ),원정민 ( J. M. Won ),차규호 ( K. H. Cha ),류민영 ( M. Y. Lyu ) 한국고무학회 2012 엘라스토머 및 콤포지트 Vol.47 No.4
사출성형품에서 잔류응력은 성형공정 중 열과 전단응력에 의해 형성된다. 잔류응력을 평가하는 방법은 여러 가지가 있는데, 불투명한 제품에서의 잔류응력은 케미칼 크랙킹 테스트 방법으로 측정 할 수 있다. 이 방법은 시편과 솔벤트가 반응하게 하여 측정하는 방법이다. 크랙은 응력의 크기에 따라 형성되기 때문에 크랙의 크기나 수를 측정하여 응력을 정량적으로 측정한다. 본 연구에서는 케미칼 크랙킹 방법으로 잔류응력을 측정하기 위한 기초자료인 응력과 크랙과의 관계를 규명하기 위한 실험을 수행하였다. 시편을 제작하기 위한 재료는 PC/PBT와 PC/ABS사용하였으며 지그를 이용하여 시편을 변형을 주고 이를 솔벤트에 담궈서 크랙을 유도하였다. 솔벤트는 tetrahydrofuran과 methyl alchol을 이용하여 제조하였다. 두 재료 모두 응력이 어느 정도 이상에서만 크랙이 형성되었으며, 크랙은 응력이 증가함에 따라 대략 2차함수로 증가하였다. Residual stress in the injection molded part is originated from thermal shrinkage and shear stress during injection molding process. There are many measurement methods of residual stress in the plastic part. Residual stress in opaque products can be measured by chemical cracking test. This method enables the solvent and specimen to react and to cause cracks. Cracks developed according to the level of residual stress. Thus the stresses in plastic part can be quantitatively measured by counting the number of cracks or measuring the size of cracks. Relationship between stress and number of cracks in a plastic specimen has been investigated in this study. Bergen jig was used to give a strain in the specimens those were molded using PC/PBT and PC/ABS. Solvent for the chemical cracking test was prepared using tetrahydrofuran and methyl alcol with the ratio of 1 to 3. Stresses in the specimen can be calculated by strains those were imposed by Bergen jig. Cracks were developed for stress higher than certain level. The number of cracks increased by second order function for stress.
3.3kV(105A) COMPACT RACK TYPE 고압 인버터 시스템의 방열 성능 향상을 위한 열유동 해석
김선영(S. Y. Kim),김성대(S. D. Kim),유성열(S. R. Ryoo),유남규(N. K. You),김태범(T. B. Kim),홍찬욱(C. O. Hong) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5
With ever-rising concerns about saving of fossil fuel resource, there have also been an increasing demand for using of energy more efficiently. The electric motor driven inverters can be a great help to improve energy efficiency. They are used to control the motor speed to the actual need. Therefore the use of them can lead to reduce energy consumption. In particular, the medium voltage(MV) drive systems which are used for pumps, fans, steel rolling mills and tractions have widespread applications in the industry. They covers power ratings from 0.4MW to 40MW at the medium-voltage level of 2.3kV to 13.8kV. However, the majority of the installed MV drive systems are in the 1MW to 4MW range with voltage rating from 3.3kV to 6.6kV. Recently, they also have been required to reduce size and weight like other power electronic equipments. In this paper, we studied on the 3.3kV(105A) compact rack type inverter system for improving of cooling efficiency. At first, we confirmed the tendency of temperature to compare with computational simulation using ANSYS ICEPAK and actual experimental tests. And then we researched thermal performance improvement designs in order to reduce temperature of the transformer for the safe operation. As a result, we found out more efficient solution by thermal-fluid analysis.
3.3㎸(105A) COMPACT RACK TYPE 고압 인버터 시스템의 방열 성능 향상을 위한 열유동 해석
김선영(S.Y. Kim),김성대(S.D. Kim),유성열(S.R. Ryoo),유남규(N.K. You),김태범(T.B. Kim),홍찬욱(C.O. Hong),고한서(H.S. Ko) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.3
With ever rising concerns about saving of fossil fuel resource, there have been an increasing demand for use of energy more efficiently. The electric motor driven inverters can be a great help to improve energy efficiency. They are also used to control the motor speed to the actual need. Therefore the use of them can lead to reduce energy consumption. In particular, the medium voltage(MV) drive systems used for pumps, fans, steel rolling mills and tractions have widespread applications in the industry. They cover power ratings from 0.4㎿ to 40㎿ at the ㎹ level of 2.3㎸ to 13.8㎸. The majority of the installed MV drive systems however, are in the 1㎿ to 4㎿ range with voltage rating from 3.3㎸ to 6.6㎸. But they are required to reduce size and weight like other power electronic equipments. In this paper, we studied on the 3.3㎸(105A) compact rack type inverter system for improving the cooling efficiency. At first, we confirmed the tendency of temperature with computational simulation using ANSYS ICEPAK and actual experimental tests. And then we researched thermal performance improvement designs in order to reduce temperature of the transformer for the safe operation. It can reduce temperature of transformer that using pipe type flow guide in the system. As a result, we found out more efficient solution by thermal-fluid analysis.