• Journal of Digital Convergence
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• v.20 no.1
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• pp.185-190
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• 2022

Bluetooth is a common wireless technology that is widely used as a connection medium between various consumer electronic devices. The Bluetooth receiver usually adopts a Viterbi algorithm to improve signal-to-noise ratio performance, but requires complex hardware and calculations for continuous search and estimation for the irrational modulation indexes at the transmission. This paper proposes a non-coherent maximum estimation based 8-State Viterbi FSM to solve these complexity problems. The proposed optimal Viterbi FSM can detect Gaussian frequency-shfit keying symbol without any prior information and estimation for the modulation indexes. The HV1/HV2 packets are used for the estimation of the proposed algorithm and the simulation results have shown performance improvements with about 2dB for 10^-3 BER compared to other ideal approaches such as decision direct method.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.1
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• pp.39-44
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• 2014

This study was conducted to investigate the effect of the addition of lactic acid bacteria (LAB) and chlorella on the change of nutritive value, quality and microbes regarding the mixture silage of Italian ryegrass and hairy vetch (IRG-HV silage). The content of crude protein of IRG-HV silage in only the LAB treatment was not different as compared to the control. However, the content of crude protein significantly increased in the treatment of LAB with chlorella, compared to both the control and LAB treatments (p<0.05). Acid detergent fiber, neutral detergent fiber, total digestible nutrient and in vitro dry matter digestibility of IRG-Alfalfa silage were not significantly different in all treatments. Further, the pH of IRG-HV silage in only the LAB treatment was not different as compared to control, but decreased in both LAB and chlorella treatments (p<0.05). The content of lactic acid in the LAB treatment increased as compared to the control, and also significantly increased in the LAB treatment with chlorella (p<0.05). In addition, the number of LAB in LAB treatment increased as compared to the control, and significantly also increased in the LAB treatment with chlorella (p<0.05). Therefore, we suggest that IRG-HV silage improved with addition of both LAB and chlorella.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2563-2566
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• 2013

Background: Interleukin-33 (IL-33) has recently been implicated in tumor immunity. The aim of this study was to explore the clinical role of serum IL-33 in patients with non-small-cell lung cancer (NSCLC). Methods: Sera collected from 250 healthy volunteers (HV), 256 patients with benign lung diseases (BLD) and 262 NSCLC cases were subjected to IL-33 ELISA and relationships between serum IL-33 and clinical characteristics were evaluated. Results: Circulating IL-33 levels were higher in the NSCLC group in comparison with the HV and BLD groups (p<0.001). Using a cut-off level 68 pg/ml (95% specificity in the HV group), IL-33 showed a good diagnostic performance for NSCLC. Multivariate survival analysis indicated that serum IL-33 was an independent prognostic factor in the entire NSCLC group [hazards ratio (HR) = 0.64 for low versus high IL-33 levels, 95% confidence interval (CI) 0.50-0.82; p<0.001] and in 165 selected patients with locally advanced or metastatic disease receiving chemoradiotherapy or chemotherapy (HR 0.70, 95% CI 0.52-0.94; p=0.013). Conclusions: IL-33 is a promising potential diagnostic and prognostic marker in NSCLC, independent of the therapeutic intervention.

• Journal of Welding and Joining
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• v.27 no.5
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• pp.81-87
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• 2009

Recently, extruded aluminium-alloy panels have been used in the car bodies for the purpose of the light-weight of railway vehicles and FSW(Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. This paper presents the optimum design of the FSW process on A6005 extruded alloy for railway vehicles to improve its mechanical properties. Rotational speed, welding speed and tilting angle of the tool tip were chosen as design parameters. Three objective functions were determined; maximizing the tensile strength, minimizing the hardness and maximizing the difference between the normalized tensile strength and hardness. The tensile tests and the hardness tests for fifteen FSW experiments were carried out according to the central composite design table. Recursive model functions on three characteristic values, such as the tensile strength, the hardness difference(${\Delta}Hv$) and the difference of normalized tensile strength and ${\Delta}Hv$, were estimated according to the classical response surface analysis methodology. The reliability of each recursive function was verified by F-test using the analysis of variance table. Sensitivity analysis on each characteristic value was done. Finally, the optimum values of three design parameters were found using Sequential Quadratic Programming algorithm.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.134-144
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• 1996

A study was performed to investigate the properties of base metal and weldment for two HSLA steels and one HY-100 steel. Tensile, yield strength and elongation of HSLA-A steel were superior to those of HY-100 steel and yield ratios in HSLA-A and HSLA-B steels were higher than HY-100 steel owing to the precipitation of $\varepsilon$-Cu phase. The impact energy of HSLA-A steel was greater at all aging temperatures than that of HY-100 steel. HSLA-A and HY-100 steels had low impact transition temperature of about -l$25^{\circ}C$ and high upper shelf energy, The peak hardness of weldment in HSLA-A, HSLA-B and HY-100 steels were Hv 299, Hv 275 and Hv 441, respectively. The hardenability of HY-100 steel was largest due to the higher amount of carbon. The y-groove test showed that HSLA steels had superior resistance to cold cracking. Toughness of weld joint at the F. L. and F. L. ＋1mm in HSLA-A was almost the same as HY-100, but those at F. L.＋3mm and F. L.＋5mm was greater in HSLA-A steel.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.75-81
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• 2018

In this study, the simulation of partial discharge pulse waveform have been performed for the typical joints such as EBA and PMJ in the HV underground transmission XLPE cable system in order to improve the understanding of partial discharge pulse waveform and the on-site measurement accuracy of partial discharges. FDTD simulation technique was adopted for the simulation and has been shown to be suitable for partial discharge simulation of power cables in terms of pulse propagation characteristics and waveform formation. The simulation results for the EBA showed that the second not-so-large opposite polarity peak appeared after the first negative polarity peak and the measurement sensitivity was the highest near the bottom of the EBA copper box. In the analysis results for PMJ, the magnitude of the second opposite polarity peak was large enough to compare with the first peak, and the measurement sensitivity at the end of the PMJ copper box was the highest. These simulation results show considerable similarity with the on-site measurement, and it would be very useful for the partial discharge measurement of HV XLPE cable systems.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.1
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• pp.3-9
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• 2006

The phase changes, nitride precipitation and hardness variations of 14%Cr-6.7Ni-0.65Mo-0.26Nb-0.05V-0.03C super martensitic stainless steel were investigated after nitrogen permeation heat treatment at a temperature range between $1050^{\circ}C$ and $1150^{\circ}C$. The nitrogen-permeated surface layer was transformed into austenite. The rectangular type NbN, NbCrN precipitates and fine round type precipitate were coexisted in the surface austenite layer, while the interior region that was free from nitrogen permeation kept the martensitic phase. The hardness of surface austenite showed 280 Hv, while the interior region of martensite phase represented 340 Hv. When tempering the nitrogen-permeated steel at $450^{\circ}C$, a maximum hardness of 433 Hv was appeared, probably this is attributed to the secondary hardening effect of the precipitates. The nitrogen concentration decreased gradually with increasing depth below the surface after showing a maximum of 0.3% at the outmost surface. The strong affinity between nitrogen and Cr enabled the substitutional element Cr to move from interiors to the surface when nitrogen diffuse form surface to the interior. Corrosion resistance of nitrogen permeated steel was superior to that of solution-anneaed steel in the solution of 1N $H_2SO_4$.

• Journal of the Korean Society of Safety
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• v.2 no.1
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• pp.31-41
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• 1987

The surface rolling method which is one of the plastic deformation processes increases the surface roughness with reduction of diameter and hardness. In this study, three NACHI 6000 ZZ bearing were used for surface rolling tool on a mild steel. The following results have been obtained with the mild steel. 1) The load is major factor in getting fine surface roughness of roller fininshing after grinding. The optimal surface roughness of SS40 steel can be obtained at the contact pressure of $210kgf/cm^2$. But, Better surface roughness can not be expected, Due to flaking phenomena at more than 300 kgf/cm of contact pressure. 2) At the contact pressure range of $200kgf/cm^2{\sim}210kgf/cm^2$ for optimal surface roughness, The surface hardness increased to Hv 200~Hv 240 from Hv 125 before surface rolling. 3) Within the diameter variation of $13{\mu}m$ the surface roughness and the surface hardness were increased, but out of variation of $14{\mu}m$. The surface roughness become worse and the surface hardness was increased.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.254-259
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• 2015

This paper reports the optimized mixed-signal performance of a high-voltage (HV) laterally double-diffused metaloxide-semiconductor (LDMOS) field-effect transistor (FET) with a dual gate oxide (DGOX). The fabricated device is based on the split-gate FET concept. In addition, the gate oxide on the source-side channel is thicker than that on the drain-side channel. The experiment results showed that the electrical characteristics are strongly dependent on the source-side channel length with a thick gate oxide. The digital and analog performances according to the source-side channel length of the DGOX LDMOS device were examined for circuit applications. The HV DGOX device with various source-side channel lengths showed reduced by maximum 37% on-resistance (R_ON) and 50% drain conductance (g_ds). Therefore, the optimized mixed-signal performance of the HV DGOX device can be obtained when the source-side channel length with a thick gate oxide is shorter than half of the channel length.

• Journal of Welding and Joining
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• v.14 no.2
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• pp.1-9
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• 1996

철강재료에 대한 플라즈마질화법의 적용에는 지금까지 많은 연구결과가 나와 있는데, 탄소강이나 적합금강의 경우는 그 표면정도가 Hv400 - 900, 고합금강의 경우 는 Hv1000이상의 정도를 얻을 수 있으며, 내마모성도 향상한다고 알려져 있다. 그리 고 플라즈마질화처리에 의한 질화층의 형성기구나 화합물층 및 확산층의 생성에 관여 하는 처리조건의 영향, 질화층의 경도 및 깊이에 대한 합금원소의 영향등이 어느 정도 밝혀져 있다. 그리고 스테인레스강의 경우는 그 표면에 견고한 산화피막을 형성하기 때문에 염욕질화나나 가스질화법에 의한 처리가 일반적으로 곤란하다. 그러나 프라 즈마질화처리에 의하면, 분위기를 질소와 수소의 혼합가스로 함으로서 특별한 전처리 를 하지않고도 질화처리가 가능한 것으로 알려져 있다. 또한 철강재료 이외의 비철 금속에 대한 플라즈마질화처리의 적용이 검토되었으며, 질화물을 형성하기 쉬운 Ti 와 그 합금, Zr, Al 그리고 Va, AIa족원소의 경우는 Hv1000이상의 경도가 얻어진다는 것과 최적 질화조건등이 보고되어져 있다. 또한 질화물을 형성하지 않는 금속, 즉 Ni 나 Cu합금 등에 대하여도 Ti, Al 등의 질화물생성원소를 첨가하여 플라즈마질화법에 의한 표면경화특성도 검토되고 있다. 본 해설에서는, 탄소강, 탄소저합금강 등의 철강 재료를 중심으로하여 플라즈마질화처리한 경우의 표면경화특성에 대하여 서술하고자 한다.