• Journal of the Korean institute of surface engineering
• /
• v.43 no.6
• /
• pp.260-265
• /
• 2010

STD 61 steel has been widely used for tools, metallic mold and die for press working because of its favorable mechanical properties such as high toughness, and creep strength as well as excellent oxidation resistance. The STD 61 tool steel coated with TiN and ZrN by sputtering results in improvement of wear and corrosion resistance. In this study, surface characteristics of TiN and ZrN film coated STD 61 by sputtering were studied by using FE-SEM, EDS, XRD, and XRR and nanoindentation tests. From the results of surface characteristics of coated specimen, the ZrN coated surface showed finer granular than that of TiN coated surface. The coated layer structures of ZrN and TiN were grown to (111) and (200) preferred orientation. From the results of XRR test for surface roughness, density and growth rate of coating film, surface roughness and growth rate of ZrN coated film revealed lower values those of TiN coated film, whereas density of ZrN coated film showed higher values than that of TiN coated film. From the nanohardness and elastic modulus test, nanohardness value and elastic modulus of ZrN coated film became higher than those of TiN coated film.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.1
• /
• pp.15-24
• /
• 2008

The data delivery confirmation method of MIL-STD-188-220C, which is a tactical wireless mobile Ad-Hoc communication protocol, is that a source node requires the end-to-end ack from all destination nodes and the data-link ack from 1-hop neighboring destination nodes and relaying nodes, regardless of the hop distance from a source node to destination nodes. This method has the problem to degrade the whole communication network performance because of excessive data traffic due to the duplicate use of end-to-end ack and data-link ack, and the collision among end-to-end acks on the wireless network in the case of confirming a data delivery within an 1-hop distance. In order to solve this problem, this paper has proposed the method to perform the data delivery confirmation with the improvement of communication network performance through the data traffic reduction by achieving the reliable data delivery confirmation requiring the only data-link ack within an 1-hop distance. The effects of the proposed method are analyzed in the two aspects of the data delivery confirmation delay time and the data delivery confirmation success ratio.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.3
• /
• pp.370-378
• /
• 2018

The mission data in missile systems should be quickly and reliably transmitted from a mission transmission device to a guidance control unit. The MIL-STD-1553B is one of the reliable communication standards, but its bit rate is generally limited to 1Mbps due to the intrinsic properties of its electrical design. Therefore, the bus controller needs to be optimized to efficiently transmit the mission data on the inevitably limited bit rate. This paper proposes an analytical approach based on sampling-based optimization methods to maximize the data throughput without data loss. The proposed approach was evaluated in the simulations with the data transmission model for the MIL-STD-1553B communication system. The results of the proposed methods were applied to a real-time system and showed that the proposed method was successfully performed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.11
• /
• pp.1129-1137
• /
• 2012

The wireless link of tactical datalink system provides a communication network to share digitalized tactical data in real-time. Also MAC(Multiple Access Control) of this system is subject to TDMA or CSMA according to a operated circumstance of target nodes to exchange the data reliably. In this paper, we verify the operability when we use CSMA scheme based on MIL-STD-188-220 in tactical datalink system which is basically designed with TDMA, and provide a mathematical analysis scheme to verify the operability and performance. Finally, by implementing CSMA scheme to a tactical datalink equipment we obtain practical results which can be compared with theoretical results.

• Journal of the Korean Society for Heat Treatment
• /
• v.16 no.3
• /
• pp.134-140
• /
• 2003

Effects of cryogenic treatment and tempering temperature on the amount of retained austenite, hardness and wear properties has been investigated using alloy tool steel, STD 11. Cryogenic treatments were performed at the temperatures of $-100^{\circ}C$, $-150^{\circ}C$ and $-196^{\circ}C$, and tempering were performed at $200^{\circ}C$ and $530^{\circ}C$. It was shown that lower hardness value was obtained on high temperature ($530^{\circ}C$) tempering even after cryogenic treatment. And retained austenite was not entirely transformed to martensite after cryogenic treatment even at $-196^{\circ}C$, which was not consistent with the belief that $-80^{\circ}C$ was sufficient to entirely transform any austenite retained in the quenched microstructure. Austenite retained in cryogenic treated condition was completely transformed to martensite only after tempering at $530^{\circ}C$. As far as wear test conditions in this investigation, it was found that cryogenic treatments improved the sliding wear resistance, but improvement of wear resistance was not directly related with retained austenite contents. And it was found that predominent wear mechanisms of STD 11 steel were oxidation wear and adhesive wear In sliding wear conditions.

• Journal of the Korean Society for Heat Treatment
• /
• v.24 no.5
• /
• pp.262-270
• /
• 2011

Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.4
• /
• pp.161-167
• /
• 2008

A method to compute the size of packet and the optimal way to transmit the packets are proposed in this work for the VoIP communication using the MIL-STD-188-220C, military wireless Ad-hoc protocol which is used for the amicable communications of both speeches and data between several radiotelegraph. The expected time of data transmission is estimated beforehand, and then the size of package and transmission method are decided in the consideration of VoIP speech quality for the users as well as the data transmission quality of radiotelegraph.

• Journal of Korean Public Health Nursing
• /
• v.25 no.2
• /
• pp.255-265
• /
• 2011

Purpose: The study investigated the knowledge and actual condition of sexuallytransmitted diseases(STD) in Mongoloian. Method: Data from 210 Mongolians were collected for 6days from August 10-15, 2008 using a questionnaire translated by Mongolians to identify the knowledge of STD and with permission, analysis of blood and human immuno deficiency virus(HIV) by SD Bioline Syphilis 3.2 test and SD Bioline HIV-1/2 3.0 test respectively. The data was scored by mean ${\pm}$ standard deviation. Differences were evaluated according to the subjects' general characteristics by t-test and the ANOVA. Results: The average knowledge score concerning STD 48.99(${\pm}.19$) indicated a low level of knowledge. STD was detected in six(2.9%) and HIV was four(1.9%) of the 210 subjects. General characteristics significantly different knowledge level were gender(t=-3.098, p=.002), education(F=6.090, p=.003), type of employment(F=2.443, p=.049), and sexual education experience(F=5.604, p=.004). Conclusion: Education programs to increase STD awareness and its prevention must be developed and regular health evaluations for those already have sexual transmitted disease is needed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.6
• /
• pp.1045-1054
• /
• 2006

In this paper, described a design result of bus interface modulo for multiple level MU-SID-1553 data bus network. In general, MIL-SID-1553 network is used for single level data bus topology. But, according to applied system's structure. multiple level bus architecture is required., And for his, micro processor must be involved for system be, and a additional hardware and software functions are needed. The designed data bus interface module is simply consists of communication transceivers and simple electronic circuit without micro processor. Through the hardware testing and software simulation, the functional performance of the designed interface module was successfully validated.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.4
• /
• pp.422-429
• /
• 2013

MIL-STD-1553B communication is globally used in the area of aerospace and defense which require safety and reliability in spite of its low communication speed. As recently increased requirements for high precision and robust guidance ability of missiles, missile sensor equipment needs more data to satisfy those requirements. Therefore, missile systems to adopt MIL-STD-1553B requires higher data transfer and processing capability than those of the current systems. In this paper, we describe the result of analysis and implementation of the existing methods that applied multi-message chain and double buffers to improve the current missile system.