• Design & Manufacturing
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• v.14 no.1
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• pp.49-55
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• 2020

In this study, the fatigue behavior and fatigue life characteristics of PA2200 specimens fabricated by SLS 3D printer were studied. Fatigue tests were performed according to the standard specification (ASTM E468) and fatigue life curves were obtained. In order to perform the fatigue test, mechanical properties were measured according to the test speed of the simple tensile test, and the self-heating temperature of the specimen according to the test speed was measured using an infrared temperature measuring camera in consideration of heat generation due to plastic deformation. There was no significant difference within the set test speed range and the average self-heating temperature was measured at 38.5 ℃. The mechanical strength at the measured temperature showed a relatively small difference from the mechanical strength at room temperature. Fatigue test conditions were established through the preceding experiments, and the loading conditions below the tensile strength at room temperature 23 ℃ were set as the cyclic load. The maximum number of replicates was less than 100,000 cycles, and the fracture behavior of the specimens with the repeated loads showed the characteristics of Racheting. It was confirmed that SLS 3D printing PA2200 material could be applied to the Basquin's S-N diagram for the fatigue life curve of metal materials. SEM images of the fracture surface was obtained to analyze the relationship between the characteristics of the fracture surface and the number of repetitions until failure. Brittle fracture, crazing fracture, grain melting, and porous fracture surface were observed. It was shown that the larger the area of crazing damage, the longer the number of repetitions until fracture.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.1-13
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• 2020

In the event of fire, it is necessary to put out the fire within a golden time to minimize personal and property damages. To this end, it is necessary for fire engines to arrive at the site quickly. This study established a fire engine travel time estimation model to secure the golden time by identifying road and environmental factors that influence fire engine travel time in the case of fire by examining data on fire occurrence with GIS DB. The study model for the estimation of fire engine travel time (model 1) covers variables by applying correlation analysis and regression analysis with dummy variables and predicts travel time for different types of places where fire may occur (models 2, 3, 4). Analysis results showed that 17 siginificant independent variables are derived in model 1 and the fire engine travel time differs depending on the types of places where fire occurs. Key variables(travel distance, number of lane, type of road) that are included commonly in the 4 models were identified. Variables identified in this study can be utilized as indicators for research related to travel time of emergency vehicles and contribute to securing the golden time for emergency vehicles.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.53-58
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• 2023

The glutamic acid producing strain for development savory taste enhancing foods was identified the possibility through application into soybean fermentation. To check the effects on glutamic acid production during soybean fermentation, Lactococcus lactis HY7803 was introduced as a starter. The soybean samples were analyzed on days 0, 7, 14 and 21. The numbers of bacteria decreased gradually, while the content of amino-type nitrogen increased during fermentation in the soybean with L. lactis HY7803. Glutamic acid content in soybeans with L. lactis HY7803 increased from 114.99 ± 9.37 pmol/ul on day 0 to 138.14 ± 1.76 pmol/ul on day 21, showing an overall higher amino acid content than soybeans without L. lactis HY7803 and similar content to soybeans with Aspergillus oryzae SNU-G. It was clearly distinguished through principal component analysis. Consequently, our results indicate that L. lactis HY7803 is available as a fungus replacement and may be a good starter strain for enhancing savory taste in vitro as well as soybean fermentation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.51-63
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• 2022

Convoy driving is one of the technologies of multi-vehicle cooperation driving along with platoon driving. All over the world, research on vehicle control mechanisms to maintain vehicle formation during convoy driving convoy driving has been actively conducted and in Europe's Autonet 2030 project has developed and demonstrated convoy driving services for highways. But, even the concept of convoy driving is still insufficient in Korea. Therefore, in this study, the concept of convoy driving service was established and scenarios and communication messages for service application on urban roads were developed. And its effectiveness was verified through simulation analysis. As a result of comparing and analyzing individual vehicle cooperative driving and convoy driving for the blind spot support service and dilemma zone safety support service, which are representative V2I cooperative driving services on urban roads, the number of conflicts(indicator of traffic safety) and delays and stops(indicator of traffic efficiency) are significantly improved in convoy driving compared to individual vehicle cooperative driving.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.359-364
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• 2010

Many therapeutic roles have been proposed for sigma-1 receptor (Sig-1R), but the involvement of Sig-1R in neuropathic pain has currently not been well explored. The present study aimed to evaluate the anti-nociceptive effect of Sig-1R antagonist (BD1047) in a rat model of chronic compression of the dorsal root ganglion (CCD), which is a model of human foraminal stenosis and radicular pain. When stainless steel rods were inserted into the intervertebral foramen of lumbar vertebrae 4 and 5, the CCD developed reliable mechanical (from 3 day) and cold allodynia (from 1 day) as compared with the sham operation group. The spinal expressions of Sig-1R and phosphorylation of extracellular signal-regulated kinase (pERK) were significantly increased from day 3 to day 14 after CCD surgery, as is consistent with the manifestation of allodynia. The BD 1047 (10, 30, 100 mg/kg) administered on postoperative days 0~5 dose-dependently suppressed both the induction of allodynia and the elevation of the spinal pERK expression in a manner comparable with that of gabapentin (100 mg/kg). At 7 days post-CCD surgery, BD1047 (10, 30, 100 mg/kg) administration also produced anti-nociceptive effects on the mechanical and cold allodynia similar with those of gabapentin (100 mg/kg). Therefore, this data suggested that Sig-1R may play an important role in both the development and maintenance of CCD-induced neuropathy.

• Polymer(Korea)
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• v.35 no.2
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• pp.146-151
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• 2011

The physical properties of poly (ethylene 2,6-naphthalate) (PEN) copolymers were studied. PEN copolymers were synthesized successfully from the mixtures of ethylene glycol(EG), 1,3-propanediol (PD) and l,4-butanediol (BD) with 2,6-dimethyl naphthalene dicarboxylate. The results indicated that PEN copolymers showed an amorphous state when the content of BD(PD) in applied EG/BD(EG/PD) mixtures was less than 40% during the polycondensation. As a result, the lowering of thermal properties, orientation, and mechanical properties was found, however, the dimensional stability was improved. This is a promising result to apply the synthesized PEN copolymers as flexibles substrates.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.98.2-98.2
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• 2016

뿌리기술은 제조기술의 근본이 되는 주조, 금형, 소성가공, 용접, 열처리 그리고 표면처리기술로 소재를 가공하여 제품을 제작하는 기초기술입니다. 국내 뿌리기업의 경쟁력을 제고하기 위해서 기획된 '17년 첨단뿌리기술 분야의 산업기술에 대한 정부의 R&BD 전략을 소개할 예정이오니 뿌리기술과 관련된 기업, 학교, 연구기관의 기술개발 계획수립에 활용하시기 바랍니다.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.4
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• pp.311-317
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• 2014

As products have been more complex and customer's demands of personalized products are increasing, manufacturing system has been changed from mass production to mass customization production that makes small quantity but different kinds of product. In addition, it becomes important that manufacturers quickly respond to variable customer's demands and characteristic regulations in each country. Therefore, three prerequisites are essential for manufacturers to response agilely. First, manufacturing data should be monitored in real time, second, information is extracted from the data, and finally, the information is used to make manufacturing strategy. In this paper, the mobile dashboard system is presented. It visualizes manufacturing data on mobile devices, and measures performance of the shop floor through the information. The proposed system is composed of server and client, and is running on the R - the open source software for statistics. Four kinds of template are given for easy visualization through the system.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.129-134
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• 2002

To isolate probiotic lactic acid bacteria having superior inhibitory activities against animal gastro-intestinal pathogenic bacteria such as Salmonella gallinarum, Staphylococcus aureus and Escherichia coli, 130 strains were initially isolated from the small intestines of Korean native chickens and 7 lactic acid bacteria were finally selected. By using API CHL kit and 16S rRNA sequencing method, the selected lactic acid bacteria were found to be belonged to genus Lactobacillus except BD14 identified as Pediococcus pentosaceus. Especially, Lactobacillus pentosus K34 showed the highest resistancy to both of HCl and bile salt, as well as the highest inhibitory activities against S. gallinarum, S. aureus and E. coli. All the selected strains were sensitive to various antibiotics such as neomycin, erythromycin, cephalosporin, amoxicillin/clavulanic acid, ampicillin, oxytetracycline, but resistant to ciprofloxacin. All the selected strains except BL strain were resistant to colistin and streptomycin, and BD14, BD16, K34 strains were resistant to gentamicin.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.22 no.1
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• pp.57-67
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• 2018

Objectives The objective of this study is to examine the interpretability of the questionnaire-based pattern identification in terms of biosignals. For this purpose, we investigate the relationship between electrochemical skin conductance (ESC) and Qi-Blood-Yin-Yang Deficiency Questionnaire (QBYY-Q) in diabetic patients. Methods A total of 40 patients with diabetes mellitus answered the QBYY-Q and their ESC were measured by SUDOSCAN device (a diabetes screening device, France). To analyze the relationship between QBYY-Q and ESC, ANOVA analysis and Scheffe test were performed and Pearson correlation coefficients were obtained. Results Of the 40 diabetic patients, 23 (57.5%) were males and 17 (42.5%) were females. According to the QBYY-Q, 9 patients were classified into Qi deficiency pattern (QD), 9 patients were Blood deficiency pattern (BD), 10 patients were Yin deficiency pattern (YiD) and 12 patients were Yang deficiency pattern (YaD). Demographic information (age, body mass index, duration of illness, etc.), signs of vitality (blood pressure, body temperature, etc.), fasting plasma glucose and glycated hemoglobin were not significantly different in each deficiency pattern. The ESC of the right leg was significantly lower in the BD group compared to the YiD group (p<0.022). Pearson's correlation coefficient was negatively correlated with the BD questionnaire score (r=-0.343, p <0.05). Finally, ESC showed a positive correlation with hemoglobin and erythrocyte levels in all limbs (r=0.483, p<0.01). Conclusions We showed that ESC could be used to classify the Deficiency pattern identifications in diabetic patients. Especially, the ESC was significantly lower in the BD group and was negatively correlated with the BD scores. It implies the potential utility of the ESC to understand the BD in terms of modern biosignals.