• The Korean Journal of Food And Nutrition
• /
• v.11 no.4
• /
• pp.402-408
• /
• 1998

A rapid processing method for fermented sauce of favorable flavor was investigated with low-usefulness marine resources. Hydrolyzed at optimal conditions for 6 hours usuing alcalase, and separated by molecularporous membrane. It's very effective for remove bitter taste at below M.W. 100 dalton, and effective at below M.W.500 dalton. Added 2% invert sugar in fermented sauce at below M.W.500 dalton, and thermal treatment at 100$^{\circ}C$ for 30 minutes were improved flavor. Chemical composition of fermented sauce using hair tail were 80.7% of moisture, 2.2% of carbohydrate, 1.8% of total nitrogen, 1.6% of amino nitrogen and pH was 6.5. The ratio of amino nitrogen in total nitrogen was 77.8%. And chemical composition of fermented sauce used gizzard shad, kangdale, pen shell and oyster were similar to fermented sauce used hair tail. Total nitrogen were above 1.8% and the ratio of amino nitrogen in total nitrogen was 77.7∼84.2% in all fermented sauce. Amino acid contents in fermented sauce used hair tail, gizzard shad, kangdale, pen shell and oyster were 4,318.1mg%, 4,681.3mg%, 3,156.2mg% and 4,175.0mg%, respectively. And the predominant free amino acid were glutamic acid, lysine and glycine in all fermented sauce.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.12
• /
• pp.1251-1257
• /
• 2014

In this paper, a 6~13 GHz ultra high speed frequency synthesizer having minimum 30 kHz step size and minimum 500 ns frequency settling time is proposed. In order to obtain fast settling time, fine resolution, and good phase noise performance, wideband output frequencies were synthesized based on DDS(Direct Digital Synthesizer) and analog direct frequency synthesis technology. The phase noise performance of wideband frequency synthesizer was estimated by the superposition theory and its results were compared with measured ones. The measured frequency settling time was below 500 ns, phase noise was below -106 dBc @ 10 kHz at 13 GHz, and frequency accuracy was measured below ${\pm}2kHz$.

• The Korean Journal of Ecology
• /
• v.7 no.4
• /
• pp.185-193
• /
• 1984

Regneration process of Abies koreana-Pinus koraiensis community consisted of a subalpione coniferous forest in Mt. Jiri, Korea, was studied in relation to age structure, especially to gap formation. The tall-tree layer (ca. 6.5m) is dominated by Abies koreana and Pinus koraiensis, while lower layer by the sapling and juveniles of A. koreana and Picea jezoensis below 2m tall. The ranges of DBH in A. koreana, P. koraiensis and P. jezonesis were 11.8cm~26.4m, 11.7cm~24.5 cm and 18.2cm~21.7 cm, respectively. The trees below 130 cm tall had contagious distribution, while tall and subtall trees had uniform distribution. The average tree ages of A. koreana, P. koraieniensis and P. jezoensis were 60~70 years, 70~80 years and 70~90 years, respectively. The saplings and juveniles below 20 years in tree ages were occupied over 80% of total trees. The coniferous trees in the gaps or around dead trees were composed of sapligs and juveniles which had emerged or invaded about 20 years before and after the gap formation. The Betula type regeneration of the coniferous forest took place in gaps which orginated from the failing down of a single or a few trees by longevity. Accordingly, it is clear that the subalpine coniferous forest composed of A. koreana of A. koreana, P. koraiensis and P. jezoensis in Mt. jiri was supporting by the regeneration pattern of Betula type.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.2
• /
• pp.190-195
• /
• 2009

Thin-gauged 3% silicon steel sheets having a highly grain-oriented texture have been developed as a core material for applications of middle-frequency (400 Hz ${\sim}$ 10 kHz) devices. The newly developed sheets with a tension coating showed an excellent reduction in iron loss at 400 Hz (iron loss at 1.0 T and 400 Hz = 4.677 W/kg, iron loss at 1.5 T and 400 Hz = 9.742 W/kg) due to high magnetic induction, $B_{10}$(measured induction at 1000 A/m), of over 1.9 T. In cases of frequencies below 400 Hz, magnetic induction, $B_{10}$, of the sample plays a major role to reduce its iron loss as excitation induction increases, whereas, in case of frequency of 1 kHz, thickness dependence becomes dominant due to a lower iron loss at relatively thinner sample. The sheets with a high magnetic induction, therefore, are favorable for high excitation induction (over 1.0 T) and low excitation frequency (below 400 Hz) applications, whereas the sheets that can reduce eddy current loss by reducing thickness or domain wall width are advantageous for low excitation induction (below 1.0 T) and high excitation frequency (around 1 kHz) applications.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3297-3304
• /
• 1994

Experimental investigation have been made to study the double-diffusive nature of convection of an initially stratified salt-water solution heated from below in a cylindrical cavity. The objective is to examine the process of mixed-layer formation, the flow phenomena, the heat transfer characteristics, and temperature and concentration distribution according to the changes in the effective Rayleigh number based on the reference height which represents the relation of temperature and concentration gradient. The types of initially formed flow pattern are categorized in three regimes depending on the effective Rayleigh number ; stagnant flow regime, single mixed-layer flow regime and successively formed multiple mixed-layer flow regime. The temperature and concentration profiles are both uniform in each layer due to convective mixing in the layered flow regime, but both linear in stagnant flow regime and single mixed-layer flow regime. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly. The layers expand by diffusion of concentration through the interface along with its random fluctuation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.466-469
• /
• 1995

This paper presents a design and performance of the 6 D.O.F linear motion table with a magnetic bearing suspension. The linear positioning of the table with a 150mm stroke is driven by a brushless DC Linear motor and the other attitudes of the stage are controlled by the analog PD controller with magnetic bearing actuators. Each magnetic bearing unit which consists of 3 electromagnets, 3 capacitance probes and 3 backup bearings affords controlled forces by detecting the air gap between the probes and guideways. An integral type capacitance probe amplifier is equipped on the upper plate of the table so that the probe line to the probe amplifier can be shorter therefore the problems due to the stray capacitance and noise can be reduced. Form the pitch-yaw errormeasured by the autocollimator, the vertical and horizont straightness errors of the table are derived that they are maintained below 1.mu. m over 100mm stroke. The positioning accuracy of the linear motion is maintained below 2 .mu. m and the repeatability error is below 1 .mu. m

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.804-807
• /
• 2007

The acid gas removal (AGR) system was designed and installed to remove $H_2S$ in coal syngas in the pilot-scale coal gasification system for producing chemicals like Dimethyl Ether(DME). The syngas from the coal gasification at the rate of $100{\sim120$ $Nm^3$/hr included pollutants such as fly ash. $H_2S$, COS, $NH_3$, etc. The designed temperature and pressure of the AGR system are below 50oC and 8 kg/$cm^2$. Fe-chelate was used as an absorbent. $H_2S$ was stably removed below 0.5 ppm in the AGR system when the concentration of $H_2S$ was $150{\sim}450$ ppm. The pH of Fe-chelate solution was also stably maintained between $8{\sim}9$. FeMgO absorbent was also tested to remove $H_2S$ in the lab-scale AGR system and $H_2S$ was also removed below 0.5 ppm in the initial operation.

• Tribology and Lubricants
• /
• v.32 no.1
• /
• pp.18-23
• /
• 2016

The effective case depth for case-hardened rolling bearing has been discussed. For this purpose, rolling contact fatigue tests for ball bearings built with inner race of various hardness values were conducted until L₁₀ calculating rating life using a bearing life test machine under radial loading. Then, the distribution of residual stress below the inner raceway, which depended on the hardness value, was measured by X-ray diffraction. As a result, the linear relationship was established between the hardness value of the inner race and the theoretical shear stress evaluated at the depth where the residual stress disappeared below the inner raceway. Based on the relationship, it could be found that the factor of safety in bearing manufacturer’s rules for the effective case depth of case hardened rolling bearings was set higher. However, it could be also found that the hardness values at the depth where the maximum shearing stress acted below the raceway surface in a tapered roller bearing hardened by the carburizing process, were not sufficient for preventing plastic deformation under the basic dynamic load rating. Consequently, further efforts were still required to reduce or to disperse the contact load on the material design of a rolling bearing in order to prolong its life.

• Journal of Powder Materials
• /
• v.11 no.1
• /
• pp.34-42
• /
• 2004

The effect of extrusion temperature on the microstructure and mechanical properties were studied in He-gas atomized $Al_{81-(x＋y)}Si_{19}Ni_xCe_y$ alloy powders and their extruded bars using SEM, tensile testing and thermal expansion testing. The extruded bar of $Al_{73}Si_{19}Ni_7Ce_1$ alloy consists of a mixed structure in which fine Si particles with a particle size below 20∼500nm and very fine $Al_3Ni,\;Al_3Ce$ compounds with a particle size below 200nm are homogeneously dispersed in Al martix with a grain size below 500nm. With increasing extrusion temperature, the microstructural scale was decreased. The ultimate tensile strength of the alloy bars has incresed with decreasing extrusion temperature from 500 to 35$0^{\circ}C$ and $Al_{73}Si_{19}Ni_7Ce_1$ alloy extreded at 35$0^{\circ}C$ shows a highest tensile strength of 810 MPa due to the fine namostructure. The addition of Ni and Ce decreased the coefficients of thermal expansion and the effects of extression temperature on the thermal expansion were not significant.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.139-144
• /
• 2002

Ti-50.9at%Ni wires were welded using pulsed YAG laser. The laser welded wires were tested for investigating the shape memo교 effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.