• Journal of the Korean Society for Heat Treatment
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• v.10 no.4
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• pp.266-277
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• 1997

Near-threshold fatigue crack growth characteristics was investigated on the Ni-Cr-Mo-V low alloy steel, which has the different microstructure obtained by tempering at various temperature. The specimens were austenized at $950^{\circ}C$ and then followed by tempering at $200^{\circ}C$, $530^{\circ}C$ and $600^{\circ}C$. Strain rate was obtained from strain gauge attached on the crack tip and crack opening point was observed through load-strain curve. Threshold stress intensity range(${\Delta}K_{th}$) was increased with increasing tempering tempuerature, but the effective threshold stress intensity rage (${\Delta}K_{eff,\;th}$) was not affected with the increasing temperature. Grain size increased with increasing tempering temperature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1369-1376
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WiMedia Distributed-MAC(D-MAC) protocol is adopted for development of a seamless N-Screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU(One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a Dynamic Threshold-based Multicast(DTM) technology is proposed and analyzed. For this technology, a new Hard/Soft Vertical Region(HVR-SVR) based time slot allocation and a multicast resource reservation scheme are combined. From simulation results, proposed DTM scheme expands the number of time slots available for unicast and multicast realtime N-Screen reservations with various service time interval requests. Furthermore, it enhances performances in vewpoints of realtime N-Screen data reservation conflict and throughput.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.44-49
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• 2018

This study analyzed the Vulnerability of Network Communication devices when IEMI is coupled with the Network System. An Ultra Wide Band Generator (180 kV, 700 MHz) was used as the IEMI source. The EUTs are the Switch Hub and Workstation, which are used to configure the network system. The network system was monitored through the LAN system configuration, to confirm a malfunction of the network device. The results of the experiment indicate that a malfunction of the network occurs as the electric field increases. The data loss rate increases proportionally with increasing radiating time. In the case of the Switch Hub, the threshold electric field value was 10 kV/m for all conditions used in this experiment. The threshold point causing malfunction was influenced only by the electric field value. The correlation between the threshold point and pulse repetition rate was not found. However, in case of the Workstation, it was found that as the pulse repetition rate increases, the equipment responds weakly and the threshold value decreases. To verify the electrical coupling of the EUT by IEMI, current sensors were used to measure the PCB line inside the EUT and network line coupling current. As a result of the measurement, it can be inferred that when the coupling current due to IEMI exceeds the threshold value, it flows through the internal equipment line, causing a malfunction and subsequent failure. The results of this study can be applied to basic data for equipment protection, and effect analysis of intentional electromagnetic interference.

• Physical Therapy Korea
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• v.5 no.2
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• pp.1-14
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• 1998

This study was conducted to examine the increasing effects of Ga-As-Al laser Koryo-hand acupuncture on experimental pressure threshold. Forty healthy subjects (female=20. male=20) aged 21 to 30 years were randomly assigned to two treatment groups with same ratio in sex. The subjects in the experimental group (n=20) received Ga-As-Al laser stimulation, and those in the control group (n=20) received sham stimulation on appropriate Koryo-hand acupuncture points M10 on the left hand which is reflex point of upper trapezius portion. Experimental pressure threshold at the contralateral upper trapezius was determined with a pressure algometer and Galvanic Skin Response (GSR) before and after treatment. The change of pressure threshold between pretreatment and posttreatment in the experimental group was greater than that in the control group (p<0.05). The result indicates that Ga-As-Al laser Koryo-hand acupuncture increases experimental pressure threshold and suggests that it is an effective noninvasive pain management technique.

• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.151-164
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• 2002

Genetic variance and covariance components of the linear traits and the ordered categorical traits, that are usually observed as dichotomous or polychotomous outcomes, were simultaneously estimated in a multivariate threshold animal model with concepts of arbitrary underlying liability scales with Bayesian inference via Gibbs sampling algorithms. A multivariate threshold animal model in this study can be allowed in any combination of missing traits with assuming correlation among the traits considered. Gibbs sampling algorithms as a hierarchical Bayesian inference were used to get reliable point estimates to which marginal posterior means of parameters were assumed. Main point of this study is that the underlying values for the observations on the categorical traits sampled at previous round of iteration and the observations on the continuous traits can be considered to sample the underlying values for categorical data and continuous data with missing at current cycle (see appendix). This study also showed that the underlying variables for missing categorical data should be generated with taking into account for the correlated traits to satisfy the fully conditional posterior distributions of parameters although some of papers (Wang et al., 1997; VanTassell et al., 1998) presented that only the residual effects of missing traits were generated in same situation. In present study, Gibbs samplers for making the fully Bayesian inferences for unknown parameters of interests are played rolls with methodologies to enable the any combinations of the linear and categorical traits with missing observations. Moreover, two kinds of constraints to guarantee identifiability for the arbitrary underlying variables are shown with keeping the fully conditional posterior distributions of those parameters. Numerical example for a threshold animal model included the maternal and permanent environmental effects on a multiple ordered categorical trait as calving ease, a binary trait as non-return rate, and the other normally distributed trait, birth weight, is provided with simulation study.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.410-417
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• 2009

The objective of this paper is to study the discharge phenomenon for a point-plane air interval using an original fuzzy logic system. Firstly, a physical model based on streamer theory with consideration of the space charge fields due to electrons and positive ions is proposed. To test this model we have calculated the breakdown threshold voltage for a point-plane air interval. The same model is used to determine the discharge steps for different configurations as an inference data base. Secondly, using results obtained by the numerical simulation of the previous model, we have introduced the fuzzy logic technique to predict the breakdown threshold voltage of the same configurations used in the numerical model and make estimation on the insulating state of the air interval. From the comparison of obtained results, we can conclude that they are in accordance with the experimental ones obtained for breakdown discharges in different point-plane air gaps collected from the literature. The proposed study using fuzzy logic technique shows a good performance in the analysis of different discharge steps of the air interval.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.733-734
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• 2016

This study proposes a novel approach for ground segmentation of 3D point cloud. We combine two techniques: gradient threshold segmentation, and mean height evaluation. Acquired 3D point cloud is represented as a graph data structures by exploiting the structure of 2D reference image. The ground parts nearing the position of the sensor are segmented based on gradient threshold technique. For sparse regions, we separate the ground and nonground by using a technique called mean height evaluation. The main contribution of this study is a new ground segmentation algorithm which works well with 3D point clouds from various environments. The processing time is acceptable and it allows the algorithm running in real time.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.1
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• pp.39-43
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• 2013

In this paper, we present a effective method of gait rehabilitation training using critical point of median frequency in muscle fatigue analysis using EMG. To target the five healthy volunteers, EMG signal were measured in the quadriceps femoris muscle and the tibialis anterior muscle in order to determine muscle fatigue. We performed a test targeting three adult male for 30 minutes on a treadmill at a speed of 6km/h same. EMG signal analysis in frequency and median frequency is calculated to quantification of muscle fatigue, and calculated the critical point which is saturated by muscle fatigue during 30 minutes. We set saturated point the threshold which muscle can withstand. The results of this paper, we are able to quantify the threshold of the muscle.

• Asia-Pacific Journal of Business
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• v.11 no.2
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• pp.207-233
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• 2020

Purpose - The purpose of this paper analyzes the relationship between the Corporate Social Responsibility(CSR) and Corporate Value to estimate whether the characteristics of Firm can change this relationship. Design/methodology/approach - This paper utilizes the total 776 firms' data over the period 2014-2018, and develops a new ESG index which was estimated by PCA. Findings - First, the estimated ESG index implies that Large company has the highest value of CSR, while Medium sized and Small company have the relatively low one. And comparing to the case of 2014, the trend of ESG index in Large company does not decrease in 2018. Second, there is a clear and significant non linear relationship between CSR and corporate value, it implies that the U-shaped exists in the Korean Firms. Such a tendency is mush stronger in the Large company. Third, the new ESG index indicates that it takes more time to increase Firm value in the Medium sized and Small company while there is a high possibility of increasing value in Large company from the little gab between the threshold points and mean value of ESG. Research implications or Originality - The non linear tendency between the Corporate Social Responsibility and Corporate Value is strongly affected by Firm size and the relative high quintile of ESG, but it is less affected by Firm history.

• Journal of Korean Physical Therapy Science
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• v.2 no.4
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• pp.771-778
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• 1995

The purpose of this study was to determine the effects of linear polarized near-infrared ray radiation on experimental pain threshold in healthy adult subjects. Thirty healthy adult subjects were divided into 5 groups: 1) group 1, super lizer radiation at 0 % ; 2) group 2, super lizer radiation at 10 % ; 3) group 3, super lizer radiation at 20 % ; 4) group 4, super lizer radiation at 40 % ; 5) group 5, super lizer radiation at 80 %. The polarized near-infrared ray radiation was applied on LI 4 point of subject's right hand at a fixed time for 30 second. Experimental pain threshold were measured with electrical current on the right hand at 5 intervals for each radiation: 1) pretreat; 2) posttreat ; 3) posttreat of 1/2 hr ; 4) posttreat of 1 hr ; and 5) posttreat of 2 hrs. Data were analyzed using analyses of variance with repeated measures for pain threshold. No significant interaction between power output and time for pain threshold was found. Significant effects of power output and time for experimental pain threshold were found. Significant increase was noted in experimental pain threshold in group 4 and group 5 at posttreat, posttreat of 1/2, 1 hr and 2 hrs as a result of the applications of the polarized near-infrared ray radiation. This study indicate that polarized near-infrared ray radiation with above 40 % of power output increases pain threshold, thus possibly increasing options in choosing radiation output for treating pateint with pain. Further study is needed to compare the effects of these radiation in patients with clinical pain.