• Journal of the Korean Society for Heat Treatment
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• 제21권2호
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• pp.79-86
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• 2008

As a basic research for developing 600 MPa yield strength reinforcing steel bars, the strengthening of 0.25 wt.% carbon steel by vanadium addition was studied. The changes of microstructure and mechanical properties were investigated for the specimen V0 (0.00 wt.% V), V1 (0.03 wt.% V) and V2 (0.06 wt.% V) processed by various heat treatments. To set the heat treatment conditions, the continuous cooling transformation (CCT) curves were drawn for austenitizing temperatures of $900^{\circ}C$ and $1100^{\circ}C$. For specimens tempered at $600^{\circ}C$ after quenching from $900^{\circ}C$ and $1100^{\circ}C$, yield strength was increased by 19 MPa and 21 MPa for 0.01 wt % V addition, and tensile strength was increased by 25 MPa and 28 MPa for 0.01 wt % V addition, respectively. Also, for 0.06 wt.% V added specimens tempered after quenching and normalized, tensile strength was increased by 50 MPa and 30 MPa for increasing austenitizing temperature of $100^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.325-328
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• 2018

With the rapid development of autonomous driving technology, commercialization of freight cars and buses as well as passenger cars has come to the near future. As researches for commercialization of autonomous navigation are being actively carried out in various countries around the world, in accordance with the development of technology, this paper proposes a bus adopting a new concept of community driving technology based on C-V2X for more effective autonomous driving of buses do. In order to realize the cluster bus, we propose a more effective cluster bus using C-V2X, which is the core communication of the cluster driving, which is complementary to the existing V2X for inter-vehicle communication and vehicle-to-infrastructure communication.

• Journal of the Korean Institute of Telematics and Electronics T
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• 제35T권1호
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• pp.48-58
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• 1998

For the purpose of designing novel capacitance pressure sensor, several effects on sensitivity such as parasitic capacitance effects, temperature/thermal drift and leakage current have to be eleiminated. This paper proposed the experimental studies on frequency compensation method by electronic circuit technique, C-V converting method with switched capacitor and C-F converting method with schmitt trigger circuit. The third interface circuit by frequency compensation method is composed to eliminate the drift and leakage component by comparision sensing frequency with reference frequency. The signal transmission is realized by digital signal to minimize the influence of noise and high resolution is obtained by means of increasing the number of digital bits. In the fabricated high performance C-V interface, the offset voltage was not appeared, and in case of voltage source, 4.0V, feed back capacitance, 10㎊, the pressure, 0~10 ㎪, the sensitivity of C-V converter is 28 ㎷/㎪.V, the temperature drift characteristic, 0.051 %F.S./$^{\circ}C$ and C-F converter shows -6.6 Hz/pa, 0.078 %F.S./$^{\circ}C$ respectively, relatively good ones.

• Korean Chemical Engineering Research
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• 제51권3호
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• pp.313-318
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• 2013

In order to investigate the effect of $V_2O_5$ loading of $V_2O_5-WO_3/TiO_2$ catalyst on the NO reduction and the formation of $N_2O$, the experimental study was carried out in a differential reactor using the powder catalyst. The NO reduction and the ammonia oxidation were, respectively, investigated over the catalysts compose of $V_2O_5$ content (1~8 wt%) based on the fixed composition of $WO_3$ (9 wt%) on $TiO_2$ powder. $V_2O_5-WO_3/TiO_2$ catalysts had the NO reduction activity even under the temperature of $200^{\circ}C$. However, the lowest temperature for NO reduction activity more than 99.9% to treat NO concentration of 700 ppm appeared at 340 with very limited temperature window in the case of 1 wt% $V_2O_5$ catalyst. And the temperature shifted to lower one as well as the temperature window was widen as the $V_2O_5$ content of the catalyst increased, and finally reached at the activation temperature ranged $220{\sim}340^{\circ}C$ in the case of 6 wt% $V_2O_5$ catalyst. The catalyst of 8 wt% $V_2O_5$ content presented lower activity than that of 8 wt% $V_2O_5$ content over the full temperature range. NO reduction activity decreased as the $V_2O_5$ content of the catalyst increased above $340^{\circ}C$. The active site for NO reduction over $V_2O_5-WO_3/TiO_2$ catalysts was mainly related with $V_2O_5$ particles sustained as the bare surface with relevant size which should be not so large to stimulate $N_2O$ formation at high temperature over $320^{\circ}C$ according to the ammonia oxidation. Currently, $V_2O_5-WO_3/TiO_2$ catalysts were operated in the temperature ranged $350{\sim}450^{\circ}C$ to treat NOx in the effluent gas of industrial plants. However, in order to save the energy and to reduce the secondary pollutant $N_2O$ in the high temperature process, the using of $V_2O_5-WO_3/TiO_2$ catalyst of content $V_2O_5$ was recommended as the low temperature catalyst which was suitable for low temperature operation ranged $250{\sim}320^{\circ}C$.

• Journal of Korea Foundry Society
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• 제7권1호
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• pp.53-59
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• 1987

In order to study the infuence of Sb addition on the compacted vermicular graphite cast iron(C/V) and gray cast iron(GC), these specimen which had different Sb content(0-0, 1wt.%) were prepared. these specimen were tested for microstructure and mechanical properties. The result from this study are as follows. For C/V and GC, the microstructure of graphite appeared to be finer with increasing Sb content more than 0.06wt.% Ferrite disappeared from the matrix with addition of Sb more than 0.06wt.% in GC and more than 0.08wt.% in C/V. The size of the eutectic cell in GC was 4.5 to 7 times larger than that in C/V, but the decreasing tendancy of its size was more remarkable in GC than in C/V with increasing Sb content. The abrasion speed corresponding to the maximum amount of abrasion in the nabrasion test was found to be 1.37m/sec. GC sample weared 3.6 to 21 times faster than those of C/V did. the amount of abrasion demeased remarkably with Sb addition, and the abrasion rate was constant with Sb content over 0.04wt.%

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.644-647
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• 2001

The investigations were discussed on the radiation effects of the electrical properties to the p-type MOS capacitors, which were irradiated by cobalt-60 gamma ray sources. The characteristics of capacitance-bias voltage(C-V) and of dielectric dissipation tarter-bias voltage(D-V) on the capacitors were measured at 1 [MHz] frequency. The microscopic behaviors of spate charges in oxide and silicon-silicon dioxide(Si- $SiO_2$) interface were investigated from the experimental data. The C-V characteristics are statical and convenient for the evaluation of the steady state behavior of carriers and interface states characteristics. While, the distribution and magnitude of space charges in oxide can be found out accurately on the $V_{dp}$ in D-V curves. The density of interface states can be deduced with ease from the magnitude of D-peak at depletion state. Thus, it is also concluded that the D-V curves are more useful and easier than conventional C-V curves for analysis of the microscopic and dynamic behavior of carriers in oxide and Si- $SiO_2$interface.

• The Korea Journal of Herbology
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• 제25권3호
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• pp.111-116
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• 2010

Objectives : This experimental study was performed to investigate the antibacterial effect of Caesalpinia sappan and Coptis chinensis extract against B. cereus and V. parahaemolyticus. Methods : Methanol extracts of C. sappan and C. chinensis was tested against B. cereus and V. parahaemolyticus by paper disc method. Results : The growth of B. cereus and V. parahaemolyticus was inhibited by C. sappan and C. chinensis extract among 6 kinds of medicinal plant extracts. The extract of C. sappan and C. chinensis extract inhibited the growth of V. parahaemolyticus and B. cereus, respectively. The growth of B. cereus and V. parahaemolyticus had a tendency to increase depend on the concentration of the extract. EtOEt and EtOAc fractions and EtOEt and BuOH fractions of the C. sappan extract had a high antibacterial activity against B. cereus and V. parahaemolyticus, respectively. And, BuOH and $H_2O$ fractions of the C. chinensis extract showed antibacterial activity against B. cereus highly. Conclusions : C. sappan and C. chinensis extract efficiently inhibited the growth of B. cereus and V. parahaemolyticus.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1356-1361
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• 2018

Replacing conventional Si diodes with SiC diodes in Si insulated gate bipolar transistor (IGBT) modules is advantageous as it can reduce power losses significantly. Also, the fast switching nature of the SiC diode will allow Si IGBTs to operate at their full high-switching-speed potential, which at present conventional Si diodes cannot do. In this work, the electrical test results for Si-IGBT/4HSiC-Schottky hybrid substrates (hybrid SiC substrates) are presented. These substrates are built for two voltage ratings, 1.7 kV and 3.3 kV. Comparisons of the 1.7 kV and the 3.3 kV Si-IGBT/Si-diode substrates (Si substrates) at room temperature ($20^{\circ}C$, RT) and high temperature ($H125^{\circ}C$, HT) have shown that the switching losses in hybrid SiC substrates are miniscule as compared to those in Si substrates but necessary steps are required to mitigate the ringing observed in the current waveforms. Also, the effect of design variations on the electrical performance of 1.7 kV, 50 A diodes is reported here. These variations are made in the active and termination regions of the device.

• Korean Journal of Food Science and Technology
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• 제26권3호
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• pp.204-212
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• 1994

To estimate the possibility of wine-making with Korean dried persimmon, its homogenized and filtered solution was fermented at $15^{\circ}C$ and $25^{\circ}C$ for 12 weeks with Saccharomyces cerevisiae (Japan Alcoholic Beverage Association N0.7). Sugars of dried persimmon were mainly composed of 27.02% of glucose, 19.81% of fructose and 5.12% of mannose. In the fermentation at $25^{\circ}C$, glucose was almost completely consumed in 8 days, but fructose and mannose were consumed up to 64% and 74%, respectively, in the same period and were not utilized any more afterwards. In the fermentation at $15^{\circ}C$, 75% of glucose, 20% of fructose and 49% of mannose were consumed in 8 days and these sugars were continuously utilized for 12 weeks. Organic acids in the homogenized and filtered solution were levulinic acid (148.6 mg%), 4-methylvaleric acid (73.5 mg%), oxalic acid (28.7 mg%), acetic acid (8.5 mg%), N-butyric acid (8.4 mg%) and succinic acid (6.7 mg%). Irrespective of fermentation temperature, levulinic acid rapidly reduced according to progression of fermentation. Oxalic acid, N-butyric acid and succinic acid decreased at 2nd day of fermentation, and then increased at 4th and 6th days and subsequently decreased again under the levels of the solution. Acetic acid and 4-methylvaleric acid increased with the proceeding of fermentation and at 12th week of fermentation these contents were more than those of the solution. The contents of total free amino acid significantly reduced at 2th day of fermentation and then increased to the level of the solution at 12th week irrespective of fermentation temperature. Ethanol content rapidly increased to the levels of 5.3(v/v) at $15^{\circ}C$ and 9.4%(v/v) at $25^{\circ}C$ to 8th day after fermentation, but at 12th week its content was 14.5%(v/v) at $15^{\circ}C$ and 9.4%(v/v) at $25^{\circ}C$. The higher alcohots identified were 2-methyl-l-propanol, 3-methyl-ibutanol, 2-methyl-l-butanol and 2-methyl-2-propanol and the range of those contents was from 0.001% (v/v) to 0.06%(v/v). The color of the wine fermented at $15^{\circ}C$ was slightly superior but flavor and taste were slightly superior in the wine fermented at $25^{\circ}C$.

• Korean Journal of Materials Research
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• 제10권2호
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• pp.144-147
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• 2000

10%C-5%Mo-5%W-10%Cr 및 10%C-5%Mo-5%W-10%V 백주철의 응고거동을 열분석을 통하여 연구하였다. 15Kg 용량의 고주파 유도옹해로에 선철, 고철, Fe-Mo, Fe-W, Fe-Cr, Fe-V 등을 장입시켜 용해시킨 후 슬래그를 제거시키고 $1550^{\circ}C$에서 Y블럭의 펩 주형에 주입하였다. 응고거동을 조사하기 위하여 50g을 Y블럭에서 채취한 뒤 알루미나 도가니에 넣어 재용해시킨 후 1$0^{\circ}C$/min의 냉각속도로 냉각시키면서 여섯 종류의 다른 온도에서 도중에 급냉시켜 응고조직을 광학현미경으로 관찰하였다. 10%C-5%Mo-5%W-10%Cr 백주철의 경우 초정 오스테나이트, 오스테나이트와 M(sub)7C(sob)3의 공정, 오스테나이트와 M(sub)6C의 공정으로, 10%C-5%Mo-5%W-10%V 백주철의 경우 초정 MC, 오스테나이트와 MC의 공정, 오스테나이트와 M(sub)2C의 공정으로 각각 순차적으로 정출하였다. 정출하였다.