• Journal of Powder Materials
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• v.6 no.1
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• pp.18-35
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• 1999

Phase equilibria in the system Si3N4-TiC-TiCxN1-x-C-N were determined by thermodynamic calculations (CALPHAD-method). The reaction peaction paths for Si3N4-TiC and SiC-TiC composites in the Ti-Si-C-n system were simulated at I bar N2-pressure and varying terpreatures. At a temperature of 1923 K two tie-triangles (TiC0.34N0.66+SiC+C and TiC0.13N0.87+SiC+Si3N4) and two 2-phase fieds (TiCxN1-x+SiC; 0.13

• Journal of the Korean Ceramic Society
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• v.24 no.1
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• pp.23-32
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• 1987

Synthesis of high purity ultrafine Si3N4 and ${\beta}$-Sialon powders was investigated via the simultaneous reduction and nitriding of amorphous SiO2, SiO2-Al2O3 system prepaerd by hydrolysis of alkoxides, using carbonablack as a reducing agent. In Si(OC2H5)4-C2H5 OH-H2 O-NH4OH system, hydrolysis rate increased with increasing reaction temperature and pH. Pure ${\alpha}$-Si3N4 was formed at 1350$^{\circ}C$ for 5 hrs in N2 atmosphere. In Si(OC2H5)4-Al(OC3H7)3-C6H6-H2 O-NH4OH system, weight loss increased as Si/Al ratio decreased. Single phase ${\beta}$-Sialon consisted of Si/Al=2 was formed at 1350$^{\circ}C$ in N2 and minor phases of ${\alpha}$-Si3N4, AIN, and X-phase were existed besides theSialon phase at other Si/Al ratios. The Si3N4 and Sialon powders synthesized from alkoxides consisted of uniform find particles of 0.05-0.2$\mu\textrm{m}$ in diameter, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.757-765
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• 2021

To carry out multi-domain operations included in the U.S. Department of Defense's national security strategy in 2018, timely data sharing between C4I systems is critical. Several studies of the Korean military have also raised the problems of interface and standardization between C4I systems, and it is necessary to establish a new plan to solve this problem. In this study, a solution to the problem was derived through case analysis that the U.S. Department of Defense has been pursuing for about 20 years to implement the data strategy after establishing the data strategy in 2003. and by establishing a data strategy suitable for the ROK military C4I system operating environment, developing a data model, selecting a standard for data sharing, and proposing a shared data development procedure, we intend to improve the data sharing capability between ROK military C4I systems.

• Journal of the Optical Society of Korea
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• v.13 no.4
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• pp.464-467
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• 2009

The grating projection method with phase-shifting technique is very useful in measuring the 3-dimensional (3D) shape with high accuracy and speed. In this work, we have developed an ultra high-speed digital laser grating projection system using a high-power laser diode and a highsensitivity CMOS camera. With our system, the optical measurement required to find out the profile of a 3D object could be carried out within 2.6 ms, which is a significant ($\sim$10 times) improvement compared with those of the previous studies.

• Convergence Security Journal
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• v.12 no.4
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• pp.57-69
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• 2012

C4ISR system is an important tool for military operational command and control. Therefore, it is frequently exposed to the cyber-terror attempt to paralyze the military command and control system. Generally, the information system uses IDS and firewall as major security computing tools. C4ISR system also uses them as major measures for the information protection. But the usefulness of IDS is reduced due to the frequent false-positives and false-negatives if the behavioral patterns are modified or new behavioral patterns appear. This paper presents new IDS structure which can create modified attack patterns and unexpected attack patterns automatically during IDS probing process. The proposed IDS structure is expected to enhance the information protection capability of the C4ISR system by reducing false-positives and false-negatives through the creation and verification of new attack patterns.

• Journal of the Korean Ceramic Society
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• v.21 no.2
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• pp.143-148
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• 1984

In this study we mainly dealt with the effects of organic retarder(calcium lignosulfate) on the early hydration process of clinker minerals. From a consideration of the hydration process of tricalcium silicate $(C_3S)$ tricalcium silicate $(C_3S)$-tricalcium aluminate $(C_3A)$ tricalcium silicate $(C_3S)$-tetracalcium aluminof-errite $(C_4AF)$ systems with calcium lignosulfate the following results were obtained. 1. when 0.25wt% of CLS was added to $C_3S$ the hydration process was progressed normally but adding of 0.5wt% its hydration was greatly retarded. 2. The hydration of $C_3S$-$C_3A$ system was progressed normally up to 0.5wt% but by adding gypsum its hydration was retarded slightly. 3. The hydration of $C_3S$-$C_4AF$ system was greatly retarded even with 0.25wt% of CLS but by adding gypsum its hydration process was recovered normally.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.4
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• pp.1-16
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• 2011

It is important not only to introduce the C4I(Command and Control, Communication, Computer, Intelligence) system for realizing the NCW(Network Centric Warfare) but also to evaluate the synergistic effect by the C4I system. However, the study effort for evaluating the system's synergistic effect is insufficient compared with introducing the system. Therefore, in this paper, we proposed a model that measures the synergistic effect of combat power by the warfare information system. To measure the synergistic effect of warfare information system, the network power must be considered, so we also proposed a new methodology for measurement of network power based on SNA(Social Network Analysis), not Metcalfe's law. A model we proposed is a model that measures the raised combat power by the network effectiveness. The methodology and model we proposed in this paper will be used usefully to analyze the practical effect of constructing future warfare information system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.352-361
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• 2000

The performance of a multi-carrier CDMA system is analyzed considering frequency selective multipath fading and Near/Far effects. The number of multicarrier, multiuser, and arms of RAKE receiver, and the decay ratio of frequency selective multipath fading are used as a parameter for the performance analysis. More over, the distribution and the strength of multiuser interference are also considered. To evaluate the Near/Far effects in a multi-carrier CDMA system, three distribution models are assumed. In the first model, interference to carrier Ratio, I/C, ranges from -4 dB to 4dB, and at each 2 dB interval, 20 % of multiuser is assumed to be uniformly distributed. In the second one, I/C ranges from -2 dB to 2 dB, and 33.3% of multiuser is assumed to be equally dispersed at each 2dB interval. The third model is 0 dB of I/C, that is, with perfect power control, multiuser are assumed to be evenly located. In this paper, multi-carrier CDMA system adoption RAKE receiver is proposed to mitigate the frequency selective multipath fading. From the results, the third model(i.e. perfect power control) shows the best performance, and the narrower range of I/C causes the less effects to the desired signal, which reads to the better performance.

• Journal of Korean Academy of Nursing
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• v.9 no.2
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• pp.73-83
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• 1979

The objectives of this study have been conducted to establish effective clinical teaching program to I.C.U in terms of proper assignment of the clients for the students, proper rotation schedule, priorities in critical nursing problems and selection of the teaching and learning. We have analyzed statistically 1,850 patients who have been admitted during a period from January 1977 to October 31 1979 in Ewha Woman's University Hospital. The results are as follows: 1. The proportion to the total inpatients number was 6.5% and mortality rate was 16.3%. 2. The average hospitalized days were 5.8 days in I.C.U and the total death was occured from 1 st hospital day to 5th hospital day. So it shows a certain difficulties for clinical experiences of the senior students in I.C.U. 3. In the age of the death, 41.3% of the patients were in the 41-60 year age group. It shows highest mortality rate in socially active and productive age groups. 4. The mortality rates of the departments of the medicine was 18.7%, general surgery 18.5%, and neurosurgery 14.7%. 5. The number of patients admitted to the department of neurosystem was 30.6%, cardiovascular system 22.6%, respiratory system 11.1 ％ and urinary system 2.9%. 6. On utilizing instruments and machine for diagnosis and client's assessment in I.C.U, they have utilized everything a usual. But they never utilize angiogram and cardiac catheterization in cardiovascular system, and retroperitoneal pneumography in the urologic system. Further more we would recommend as follows 1. In consideration of the average hospital days and the date of death, the rotation program for clincal experience need to be adjusted as continuing practice program in apposite to current alternative practice program for comprehensive nursing care. 2. Socioeconomic needs for the patient's families and himself should be emphasized by the students in addition to physical needs. 3. Course content for critical care might be built up in considering of core disease centered nursing problems. 4. The diagnostic procedures and client's assessment items which could not experience in our university hospital by the students might be considered and refilled as filled trips to another hospital and visual aids.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.781-783
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• 2000

1bit full adder have 3 input (including carry_in) and 2 outputs(Sum and Carry_out). Because of 1 bit full adder's propagation delay. We usually use 4-bit binary full adder with fast carry, 74LS283. The 74LS283 is positive logic circuit chip. But the logic function of binary adder is symmetrical, so it can be possible to use it not only positive logic but also the negative logic. This thesis use symmetrical property. such as $C_{i+1}(\bar{a_i}\bar{b_i}\bar{c_i})=C_{i+1}{\bar}(a_i,\;b_i,\;c_i)$ and $S_i(\bar{a_i}\bar{b_i}\bar{c_i})=\bar{S_i}(a_i,\;b_i,\;c_i)$. And prove this property with logic operation. Using these property, the 74LS283 adder is possile as the negation logic circuit. It's very useful to use the chip in negative logic. because many system chip is negative logic circuit. for example when we have negative logic chip with 74LS283. we don't need any not gate for 74LS283 input, and just use output of adder(74LS283) as the negation of original output.