• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.93-100
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• 2011

This study deals with the high frequency induction hardening (HF at $850^{\circ}C$, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen, which was tempered at $150^{\circ}C$, did not show any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE (acoustic emission) amplitude distribution showed between 45dB and 60dB. (2) A slip and fracture occurred at the hole area of the HF specimen which was tempered at $300^{\circ}C$. As they pass the yield point, the AE energy is increased intermittently and AE amplitude distribution exists between 70dB and 85dB. In addition, after imposing the maximum tensile load, AE signals showed high amplitude and energy distribution. The AE amplitude showed between 45dB and 70dB. (3) A brittle fracture occurred at HF specimen which was tempered at $450^{\circ}C$ as if it is torn in the direction of $45^{\circ}$ on parallel area over the both sides of the tensile specimen, which lead to several peak appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

• Progress in Superconductivity and Cryogenics
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• v.21 no.1
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• pp.18-24
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• 2019

This study was carried out to investigate the effect of milling of boron (B), which is one of raw materials of $MgB_2$, on the critical current density ($J_c$) of $MgB_2$. B powder used in this study is semi-amorphous B (Pavezyum, Turkey, 97% purity, 1 micron). The size of B powder was reduced by planetary milling using $ZrO_2$ balls (a diameter of 2 mm). The B powder and balls with a ratio of 1:20 were charged in a ceramic jar and then the jar was filled with toluene. The milling time was varied from 0 to 8 h. The milled B powders were mixed with Mg powder in the composition of (Mg+2B), and the powder mixtures were uniaxially pressed at 3 tons. The powder compacts were heat-treated at $700^{\circ}C$ for 1 h in flowing argon gas. Powder X-ray diffraction and FWHM (Full width at half maximum) were used to analyze the phase formation and crystallinity of $MgB_2$. The superconducting transition temperature ($T_c$) and $J_c$ of $MgB_2$ were measured using a magnetic property measurement system (MPMS). It was found that $B_2O_3$ was formed by B milling and the subsequent drying process, and the volume fraction of $B_2O_3$ increased as milling time increased. The $T_c$ of $MgB_2$ decreased with increasing milling time, which was explained in terms of the decreased volume fraction of $MgB_2$, the line broadening of $MgB_2$ peaks and the formation of $B_2O_3$. The $J_c$ at 5 K increased with increasing milling time. The $J_c$ increase is more remarkable at the magnetic field higher than 3 T. The $J_c$ at 5 K and 4 T was the highest as $4.37{\times}10^4A/cm^2$ when milling time was 2 h. The $J_c$ at 20 K also increased with increasing milling time. However, The $J_c$ of the samples with the prolonged milling for 6 and 8 h were lower than that of the non-milled sample.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.543-550
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• 2000

The objective of this research was to study the effect of contact force of ultrasonic probe on the ultrasonic attenuation measurement of radish. The relationship between ultrasonic attenuation (y) and contact force (x) for radish can be expressed as equation y=a+bLn(x), where a=8.7194+2.l68x(porosity) and b =-9.9188+0.0075 ${\times}$ (volume). The relationship between ultrasonic power spectrum (y) and contact force (x) for radish is also represented by equation y=a+bLn(x), where a= 60.l965-1.47l4${\times}$(porosity). The coefficient b has no significant relation with radish properties.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10B
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• pp.1482-1490
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• 2001

디지털 통신 시스템 및 신호처리 회로의 핵심 연산블록으로 사용될 수 있는 복소수 승산기 코어의 파라미터화된 소프트 IP (Intellectual Property)를 설계하였다. 승산기는 응용분야에 따라 요구되는 비트 수가 매우 다양하므로, 승산기 코어 IP는 비트 수를 파라미터화하여 설계하는 것이 필요하다. 본 논문에서는 복소수 승산기의 비트 수를 파라미터화 함으로써 사용자의 필요에 따라 승수와 피승수를 8-b∼24-b 범위에서 2-b 단위로 선택하여 사용할 수 있도록 하였으며, GUI 환경의 코어 생성기 PCMUL_GEN는 지정된 비트 크기를 갖는 복소수 승산기의 VHDL 모델을 생성한다. 복소수 승산기 코어 IP는 redundant binary (RB) 수치계와 본 논문에서 제안하는 새로운 radix-4 Booth 인코딩/디코딩 회로를 적용하여 설계되었으며, 이를 통해 기존의 방식보다 단순화된 내부 구조와 고속/저전력 특성을 갖는다. 설계된 IP는 Xilinx FPGA로 구현하여 기능을 검증하였다.

• Journal of Environmental Health Sciences
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• v.12 no.2
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• pp.67-74
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• 1986

The study was carried out to investigate for the property of Bacillus strains, on the native growthed microflora in Korean native soybean paste, and Bacillus strains of the high enzyme producing, were selected and identificated, from the microflora, that is, identificated Bacillus strains beared resemblance to B. subtills, on the colony, appearance was pellicle, surface's spreading, color creamy-thin browned, colony elevation flated, and edge lobated, the identfficated B. subtills strain named for the B. subtilis SCF. For the protease activity of B. subtilis SCF, according to the variation with pH, the pH stability was pH 7~8, and on the its protease activity, optimum temperature was 40$\circ$C, on the other hand, temperature of the highest stability of the protease was 50$\circ$C.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.83-86
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• 1989

Electrical conductivity, I - V and DLTS have been measured on polycrystalline samples of $\alpha-Fe_{2}O_{3}$ containing small deviation from stoichiometry and small amounts of added titanium. DLTS (Deep Level Transient Spectroscopy) in the current transient mode has been applied to the measurement of the trap density at the grain boundary. Titanium enters the $\alpha-Fe_{2}O_{3}$ lattice substitutionally as $Ti^{4+}$, thus producing an $Fe^{2+}$ and maintaining the average charge per cation at three. The $Fe^{2+}$acts as a donor center with respect to the surrounding $Fe^{3+}$ions.

• The KIPS Transactions:PartB
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• v.17B no.2
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• pp.125-138
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• 2010

The purpose of this research is to enhance document recognition system which is essential for developing full-text retrieval system of the document image data stored in the digital library of a public institution. To achieve this purpose, the main tasks of this research are: 1) analyzing the document image data and then developing its image preprocessing technology and document structure analysis one, 2) building its specialized knowledge base consisting of document layout and property, character model and word dictionary, respectively. In addition, developing the management tool of this knowledge base, the document recognition system is able to handle the various types of the document image data. Currently, we developed the prototype system of document recognition which is combined with the specialized knowledge base and the library of document structure analysis, respectively, adapted for the document image data housed in National Archives of Korea. With the results of this research, we plan to build up the test-bed and estimate the performance of document recognition system to maximize the utilization of full-text retrieval system.

• Journal of the Korea Fashion and Costume Design Association
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• v.10 no.2
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• pp.125-138
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• 2008

For physical and hand property evaluation of fabrics, the knitted fabrics from 11 types of machines knitting fancy yarns, boucle (M1), knot (M2), snarl (M3), and slub (M4), tamtam (M5), tubular (M6), fur 1 (M7), bead (M8), fur 2 (M9), fur 3 (M10), and ladder (M11) yarns, were prepared with 7-10 G plain stitch. Washing test and pilling test had also been carried out. For hand properties by objective sensibility evaluation, 17 items of sir mechanical properties using KES-FB (Kawabata Evaluation System) had been measured. Then hand values of knitted fabrics were calculated with a calculation formula, namely KN-402-KT. Finally the total hand values were obtained through KN-301-WINTER. As a result of physical properties and objective evaluation for machines knitting fancy fabrics, most of them shrank in the direction of wale and course after the washing test, in which their shrinkage rate had a maximum of 3.5%. Therefore, the washing test indicated that the shrinkage ratio of knitted fabrics had a minor change. The results of the pilling test are mostly 4-5th grade, and all of the machines knitting fancy fabrics showed good results in the pilling resistance. In hand properties and objective sensibility evaluation, twisted fancy yarns, such as boucle (M1), knot (M2), snarl (M3), and slub (M4), were superior to bonding rigidity (B) and shear rigidity (G). The surface property between course and wale differs in all samples and course direction is tougher than wale direction. FUKURAMI (fullness and softness) of all samples have high values, besides NUMERI (smoothness) of tamtam (M5) and boucle (M1), which were rather good. Most samples except fur 1 (M7) had low KOSHI (stiffness) value. The total hand value (THV) of twisted yarns was low. This study proves that manufacturers, who plan knitting yarn products and knit fashion, can apply these data to develop machines knitting yarns and knits that fit the consumers' demands.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.401-405
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• 2004

Undoped SrB $i_2$T $a_2$O$_{9}$, donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ and acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99$ ceramics were prepared and their microstructure, ferroelectric P-E hysteresis and Curie temperature were investigated. Grain size did not influence P-E hysteresis curve in undoped SrB $i_2$T $a_2$O$_{9}$ ceramics. Donor-Doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics showed more saturated P-E hysteresis curve with larger remanent polarization (P$_{r}$) than undoped SrB $i_2$T $a_2$O$_{9}$ ceramics while acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99}$ ceramics led to a pinched P-E hysteresis loop. Larger polarization in donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics resulted from easier domain wall motion by Sr-vacancies.

• Journal of Nutrition and Health
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• v.16 no.3
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• pp.146-153
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• 1983

In this study, buckwheat four was classified by the order of extraction from the inmost layer to the outmost layer, and was designated as $B_1,\;B_2,\;B_3,$ and the mixed flour of $B_1,\;B_2,\;B_3$ (1:1:1) was named $B_0$. To improve the dried noodle-making properties, various levels of strong wheat flour and additives such as sodium alginate (SA) and xanthan gum(XG) were added to buckwheat. 1) The buckwheat $B_2$ and $B_3$ flours contained much higher amounts of crude ash, protein and fat than the $B_1$ flour. 2) Buckwheat $B_3$ flour demonstrated lower maxium viscosity value by amylograph than the $B_1$ flour, but it demonstrated 2 times higher maximum viscosity value than wheat flour. Buckwheat $B_1$ flour demonstrated 4-5 times higher maximum viscosity value than wheat flour. Addition of SA and XG increased the viscosity of the flour mixtures. 3) It was possible to make dried noodles from the composite flour of (buckwheat 40 %+wheat 60 %). The lesser the quantity of buckwheat flour was, the better the kneading property of mixed flour was. 4) SA and XG, which were added at the level of 1.0-1.5%, significantly improved dough making properties and the cooking quality of the noodles.