• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.130-131
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• 2005

In the era of submicron devices, super ultra thin gate oxide characteristics are required. Titanium silicide process has studied gate oxide reliability and dielectric strength characteristics as the composition of gate electrode. In this study the author observed process characteristics on MOS structure. In view point of the process characteristics of MOS capacitor, the oxygen & Ti, Si2 was analyzed by SIMS analysis on before and after annealing with 1,2 step silicidation, the Ti contents[Count/sec]of $9.5{\times}1018$ & $6.5{\times}1018$ on before and after 2'nd anneal. The oxygen contents[Count/sec] of $4.3{\times}104$ & $3.65{\times}104$, the Si contents[Count/sec] of $4.2{\times}104$ & $3.7{\times}104$ on before and after 2'nd anneal. The rms value[A] was 4.98, & 4.03 on before and after 2'nd anneal.

• Journal of Welding and Joining
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• v.19 no.3
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• pp.317-324
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• 2001

This study deals with high power Nd:YAG laser welding of thin steels for small pressure vessels. Full penetration welding at the overlap joint was performed so as to assure sufficient weld strength. Results showed that mid-depth weld size reduced drastically with increasing the travel speed. Position of focus had little effect on the bead formation even though short focal system was used. However, the shape factor and the bead width had closely related with the position of focus. Based on the microstructural inspection, acceptable weld was obtained when the overlap clearance was controlled up to 20% of the base metal thickness. In the case that the joint contained more clearance than the critical value, both the tensile shear strength and the tear strength were reduced. Results also demonstrated that shielding gases were proved to play a key role as far as the bead formation characteristics was taken into consideration. Blowing dry air through 5mm in diameter nozzle produced narrower bead cross-section than that of argon or nitrogen shielding.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.144-147
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• 1988

The current-fed DC-DC converter, which is known as the most stable DC-DC converter, has a two-winding reactor in series with the input. In this paper the new multi-output DC-DC converter circuit, in which the 2nd winding of the reactor is creating the 2nd output, while the 2nd winding is feeding the energy to input in the current-fed converter, is proposed. The steady state characteristics of the new circuit are clarified. And it is found that the maximum value exists in the 2nd output.

• Journal of the Korea Safety Management & Science
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• v.8 no.1
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• pp.145-164
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• 2006

Value Engineering(VE) has been recognized by many companies as a powerful and innovative technical approach for cost down and improvement in function of product and service. VE is a discipline which use an organized, creative approach to achieve the required function at the lowest cost. For the Purpose of developing new product, at this paper used the method of 2nd look VE developing bike helmet, in the order of selecting target, function analysis and writing alternative. The development of Helmet by the process of VE job plan, achieve the cost reduction of 27 million won for developing new product with customer's need.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.204-209
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• 1990

The temperature variation at a laser rod center induced by high repetetion rate pumping was measured by counting the number of inteference frigne shift and found to be consistent with the theoretical value obtained from heat diffusion equation. The spatial homogeneity and energy transfer rate of flashlamp pumping by the single elliptical reflector plated with gold were evaluated by measuring interference fringes oever the cross section of a Nd:YAG laser rod.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.432-442
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• 2006

Statement of problem: One of common problems associated with dental implant is the loosening of abutment screws that retain the implants. Purpose : This study was performed to investigate the influence of abutment screw length and repeated tightening on screw loosening in dental implant. Material and method: Forty nine Hexplants (13mm length, 4.3mm diameter, Ti grade IV, Warantec. Co. Ltd. Seongnam, Korea) and cementation type abutments(straight abutment) and abutment screws (0.4mm/pitch) were divided into 7 groups, depending on abutment screw length. Each implant and abutment was tightened to 30Ncm by torque controller(MGT50, MARK-10 Inc., USA) and the removal torque values were measured during 10 consecutive closure/opening trials. Results and Conclusion: The results of comparing the removal torque value are as follows : 1. There is no significant difference in the removal torque value between groups in 10 consecutive closure/opening trials (p = 0.97). 2. If the fractured abutment screw is engaged in longer than 2.425 thread length, there is no significant difference in the preload between the fractured abutment screw and the new abutment screw when both are equally tightened to 30 Ncm. 3. The removal torque value in the 1st trial(24.510 Ncm) was lower than that in the 2nd, 3rd, 4th, 5th, 6th, 7th trials and the removal torque value in the 2nd trials(25.551 Ncm) was maximum and was decreased in 1311owing trials. The removal torque value in the 1st trial was significantly lower than that in the 2nd, 3rd, 4th trials and was significantly higher than that in the 8th, 9th, l0th trials(p<0.05). 4. In the 2nd, 3rd, 4th, 5th, 6th, 7th trials, the abutment screw was mainly influenced by settling effect and the higher preload was obtained In the 8th, 9th, l0th trials, the abutment screw was mainly influenced by adhesive wear and the progressively lower preload was obtained.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.330-336
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• 1996

Quality characteristics of mash of takju prepared by different raw materials such at nonglutinous rice. glutinous rice, barley and wheat flour were investigated during fermentation. At the beginning stage of fermentation, ethanol content was in the range of $0{\sim}1.2%$ but it was increased to $9.8{\sim}11.6%$ after 16 day of fermentation. takju that was made of nonglutious rice with starter showed higher ethanol content than any other treatment. At the first stage, pH of takju that was made of nonglutinous rice without starter was 6.57 while other sample showed pH $5.04{\sim}5.80.$ There was no significant difference in pH value between treatments after 2 day of fermentation. Total acid was increased rapidly at the first stage of fermentation, and increased slowly after 2 day of fermentation. Takju that was made of nonglutious rice without of fermentation, and increased slowly after 2 day of fermentation. Takju that was made of nonglutious rice without addition starer showed higher total acid content than the other teratments. Total sugar contents were $19.18{\sim}20.23%$ at the beginning of fermentation, and decreased to $5.21{\sim}14.03%$ after 2-4 days of fermentation. Takju that was made of wheat flour showed higher value of total sugar during the fermentation. Reducing sugar contents of takju decreased with fermentation progressing to $0.2{\sim}0.5%$ after 16 day if fermentation. L value decreased during the fermentation. period and that of takju that was made of barley had lowest L value among the treatment. Alcohols, such as n-propanol ($nd{\sim}0.05\;mg/ml$), iso-butanol (0.02), iso-amyl alcohol ($nd{\sim}0.13$), n-hexanol ($nd{\sim}0.17$), n-heptanol ($nd{\sim}0.09$), and phenylethanol ($nd{\sim}0.02$) were detected. There were no alcohols detected at the beginning of fermentation, but their contents were increased during fermentation.

• Journal of the Korean Magnetics Society
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• v.6 no.2
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• pp.80-85
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• 1996

An externally applied magnetic field during annealing the $Nd_{2}Fe_{14}B/Fe_{3}B$ based spring magnet was found to enhance the exchange coupling between the hard and soft magnetic grains. More than 30 % increase in remanence values for melt-spun $Nd_{4}Fe_{73.5}Co_{3}(Hf_{1-x}-Ga_{x})B_{18.5}$(x=0, 0.5, 1.0) alloys was resulted from uniform distribution of $Fe_{3}B$, $\alpha$-Fe as well as $(Nd_{2}Fe_{14}B)$, and also from reduced grain size of those phases by 20 %. The result also showed that there is an optimum grain size exhibiting a high coercivity value which will be discussed in terms of previously simulated exchange coupling parameter.

• Korean Journal of Veterinary Service
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• v.24 no.3
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• pp.217-222
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• 2001

Hemagglutination inhibition(HI) titers of Newcastle disease(ND) were measured to investigate the vaccination times on three different species of broiler chicks in Chonbuk province. Each 330 of Cobb, Ross and White-semi broiler chicks were selected from 11 broiler farms. The primary vaccine were sprayed in hatchery at one day old chicks. Secondary and tertiary vaccine were used by drinking water at 7 to 24 days old chicks. The ND antibody titer were measured by HI from each different species of broiler chicks at the marketing date. Total average HI titers of Cobbs vaccinated with primary ones, secondary and tertiary ones were recorded 1.86, 1.52 and 2.76, respectively. The antibody titers were shown to 2.22, 2.13, 3.07 in terms of vaccination of Ross broiler chicks. They were also 2.56, 2.65 and 2.78 in terms of vaccination of White-semi broiler chicks. The value HI titer were not statistically different of all treatments. The results of this experiment suggested that HI titer of sera is scored less than defensive value of ND antibody titer at more than two times of vaccination.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.193-198
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• 2008

When the existing polder levee was constructed, the river's numerical analysis decided the bank raise by applying the planned flood stage or by using the result from the sectional 1st dimensional numerical analysis. But, it was presented that there is a limitation in the 1st dimensional value analysis when the structure like the polder levee obstructs the special shaped running water flow. Therefore, in order to verify the numerical value applicability when the polder levee is constructed, this report compared each other through the 1st and 2nd dimensional numerical analysis and the mathematical principle model laboratory. In case of the polder levee construction through the numerical analysis and the mathematical principle model laboratory, it was decided that there was no big problem in the 1st dimensional numerical analysis applied design, considering the uncertainty of mathematical principle analysis though the first dimensional numerical analysis was calculated a little bigger than the second. But, after construction, it was found that the water level deviation of the 1st, 2nd occurred biggest at the place where the flow was divided into two. Also, as a result of comparing the 1st, 2nd dimensional numerical analysis with the mathematical principle model laboratory, it was confirmed that the 1st numerical analysis applied design decreased the modal safety largely, as the left side water level was calculated smaller more than 0.5m in case of the 1st dimensional numerical analysis.