• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.164-170
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• 2017

The CNC machine tool field is showing a growing trend with the recent rapid development of manufacturing industries such as semiconductors, automobiles, medical devices, various inspection and test equipment, mechanical metal processing equipment, aircraft, shipbuilding and electronic equipment. However, small and medium-sized machining companies that use CNC machine tools are experiencing difficulties in increasingly intense competition. Especially, small companies which are receiving orders from 3rd or 4th venders are very difficult in business management. In recent years, company S experienced difficulty to make product quality and delivery time due to the ignorance of the processing method when manufacturing cooling plate jig made of SUS304 material used for cell phone liquid crystal glass processing. In order to solve these problems, we redesigned the process according to the size of our company and tried to manage all processes with quantified data. In the meantime, we have found that there is a need to improve the cutter process, which accounts for most of the machining process. Therefore, we have investigated the correlation between RPM and FEED of three cutters that have been used in the past. As a result, we found that it is the most urgent problem to solve the roughing process during the cutter operation which occupies more than 70% of the total machining. In order to shorten the machining time and improve the quality in machining of SUS304 cooling plate jig, we select the main factors such as price, tool life, maintenance cost, productivity, quality, RPM, and FEED and use AHP to find the most suitable milling cutter. We also tried to solve the problem of delivery, quality and production capacity which was a big problem of S company through experiment operation with selected cutter tool. As a result, the following conclusions were drawn. First, the most efficient of the three cutters currently available in the machining center has proven to be an M-cutter. Second, although one additional facility was required, it was possible to produce the existing facilities without additional investment by supplementing the lack of production capacity due to productivity improvement. Third, the Company's difficulties in delivery and capacity shortfalls have been resolved. Fourth, annual sales increased by KRW 109 million and profits increased by KRW 32 million annually. Fifth, it can confirm the usefulness of AHP method in corporate decision making and it can be utilized in various facility investment and process improvement in the future.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.347-352
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• 2011

When concrete is worked in cold weather, the methods of using hot air, water and aggregate heating, accelerators are used to prevent early frosting and to improve early strength. But these methods raise problems such as implementation difficulty, high cost, and energy losses. Among the available cold weathering methods, accelerator method is the most economical but with the drawbacks of rapid setting and insufficient workability in the initial hydration stage. Therefore, the tablet method usually used for pharmaceutical field was applied to the accelerator method to compare the controlled reaction time of the new and old accelerator method. Based on the test results, physical and mechanical properties of concrete were tested and the possibility of delaying initial reactions to increase the total reaction time was evaluated. The results showed that when both accelerators and tablet were used, setting-time decreased. Physical properties of concrete were optimal for tablet 0.5% and 1.0%. Also, accelerator 0.5%, tablet 0.5% and 1.0% showed good early strengths.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.173-183
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• 2012

Recently, experimental studies to prevent explosive spalling based on spalling mechanism and addition of Polypropylene fiber in high strength concrete (HSC) are performed actively. However, with respect to ultra high strength concrete (UHSC), its compact internal structure is more difficult release vapor pressure at rapid rising temperature compared to HSC. Therefore, in this study, an experiment was conducted to evaluate spalling properties of UHSC using ${\Box}$ $100mm{\times}100{\times}H200mm$ rectangular specimen according to ISO-834 standard fire curve. With respect melting point of fiber, three fiber types of Polyethylene, Polypropylene, and Nylon fibers with melting temperature of $110^{\circ}C$, $165^{\circ}C$, and $225^{\circ}C$, respectively, were considered. Mixed fiber of 0.15% and 0.25% of concrete volume was used to consider spalling properties based on water vapor pressure release. Then, TGDTA test on fiber and FEM analysis were performed. The results showed that it is difficult to prevent initial spalling without loss of fiber mass even if fiber melting temperature is low. Also, in preventing thermal spalling, fiber that melts to rapidly create porosity within 10 minutes of fire is more effective than that of low melting temperature property of fiber.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1420-1426
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• 2006

To establish a rapid and effective method for the analysis of soy isoflavone which is known to have lots of variation in derivatives of glucoside, conversion rate from isoflavone conjugates to its aglycones, and decomposition of conversed aglycones were investigated with various acid hydrolysis conditions. A number of heating conditions for acid hydrolysis including heating at convection oven $(105^{\circ}C)$, water bath $(95^{\circ}C)$, heating block $(120^{\circ}C)$, and hot plate $(120^{\circ}C)$ were applied. Acid hydrolysis in heating block with reflux was chosen as the best heating condition. From the stability test of isoflavone aglycone during acid hydrolysis, genistein, daidzein, and glycitein did not show any significant changes in their contents for 60 min of hydrolysis. Ten to thirty milligram of sample per 1 mL HCl was the best ratio of sample to acid. As conclusion, acid hydrolysis for 60 min after addition of 15 mL HCl solution to 0.5 g soybean, and then fill up to 50 mL with methanol, followed by HPLC analysis was set as a final analysis method. From this method, isoflavone contents expressed as total aglycone of feed meal was the highest with content of $1288.5{\mu}g/g$ followed by those of dehulled meal.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.161-166
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• 2000

Classified handmade Korean paper which has been commonly used as the material for the paper cultural assets divide into four classes. We irradiated xenon arc lamp, which has almost the same spectrum distribution as natural sunlight, to test photo-induced of discoloration according to PEG molecular weight and concentration. So, we reach the followings. 1) Unbleached handmade Korean paper with PEG showed rapid decrease of brightness for 10 hours after photo-irradiation, regardless of molecular weight of PEG, but, after 10 hours, it showed gradual increase of brightness. From this, it proved that there was an effect of preventing discoloration of photo-irradiation. 2) Chemical bleached handmade Korean paper showed increase of brightness after 20 hours. Though time was delayed in increase of brightness, there was also an effect of preventing discoloration of photo-irradiation in chemical bleached paper. 3) Handmade Korean paper made with abet-mosk showed the lowest of brightness when it was tested on 400-20% PEG. Before photo-irradiation, the brightness of paper, applied it, was the lowest, but it showed the least difference of brightness after photo-irradiation. From this, it proved that there was the greatest effect of preventing discoloration in this paper. 4) Preventing yellowish, the first phenomena by photo-irradiation ageing with applying PEG was proved that there was the decrease of value of $b^*$ +, and increase value of $L^*$, which could fairly prevent decrease of brightness.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.817-820
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• 2008

The river environments of many streams in korea have been deteriorate through the rapid industrialization and urbanization since the 1960s. In korea, on the other hand, much efforts on the research and project have been made for the restoration of the deteriorated streams to close-to-nature. in order to restore the deteriorated streams, therefore, it is necessary to investigate such advanced technologies and materials. In view of this requirement, various research paths are being taken focusing on coarse aggregates to make multi-functional porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification and applicability to vegetation. The Purpose of this study is to investigate the method for recovery of the environment in the streams area using porous concrete retaining wall block. the multi-P.O.C block applies for test in the Jangduri-cheon have been monitored planting, stability etc. after 6 months, plant grows flourishing and reconstructed in state such as nature rivers.

• Biomedical Science Letters
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• v.25 no.4
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• pp.426-430
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• 2019

Currently, molecular diagnostic assays based on nucleic acid amplification tests have been shown to effectively detect mycobacterial infections in various types of specimen, however, variable sensitivity was shown in FFPE samples according to the kind of commercial kit used. The present study therefore used automated PCR-reverse blot hybridization assay (REBA) system, REBA Myco-ID HybREAD 480^®, for the rapid identification of Mycobacterium species in various types of human tissue and compared the conventional one-tube nested-PCR assay for detecting Mycobacterium tuberculosis (MTB). In conventional nested-PCR tests, 25 samples (48%) were MTB positive and 27 samples (52%) were negative. In contrast, when conducted PCR-REBA assay, 11 samples (21%) were MTB positive, 20 samples (39%) were NTM positive, 8 samples (15%) were MTB-NTM double positive, and 13 samples (25%) were negative. To determine the accuracy and reliability of the two molecular diagnostic tests, the one-tube nested-PCR and PCR-REBA assays, were compared with histopathological diagnosis in discordant samples. When conducted nested-PCR assay, 10 samples (59%) were MTB positive and seven samples (41%) were negative. In contrast, when conducted PCR-REBA test, three samples (17%) were MTB positive, 10 samples (59%) were NTM positive and four samples (24%) were negative. In conclusion, the automated PCR-REBA system proved useful to identify Mycobacterium species more rapidly and with higher sensitivity and specificity than the conventional molecular assay, one-tube nested-PCR; it might therefore be the most suitable tool for identifying Mycobacterium species in various types of human tissue for precise and accurate diagnosis of mycobacterial infection.

• Korean Journal of Biological Psychiatry
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• v.3 no.1
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• pp.66-74
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• 1996

There has been an increase in head trauma due to rapid industralization and improvement in transportation. This poses difficulties in differentiating between neuropsychiatric disabilities resulting from real organic changes and those arising from compensation issues. It is the purpose of this study to seek out the differences between normal and abnormal finding group in the structural brain imaging studies via the results of the functional brain imaging studies and psychological tests. Out of 132 subjects, 62 comprised normal and 70 the abnormal finding group. EEG and SPECT were chosen for inspection of functional brain imaging. MMPI and K-WAIS were chosen for psychological test. The subjects were further divided into right hemispheric damage, left hemispheric damage, both hemispheric damage, diffuse damage group and negative group in order to find out whether any differences in the psychological lest results could be localized. The results are as follows : 1) The abnormal finding group, the EEG and SPECT were proven to be a good predictor of brain lesion. This implies that even in the functional brain studies, abnormalities are more easily detected if there are visible brain lesions. 2) The FSIQ of the abnormal finding group is lower than that of normal finding group. this difference is mainly due to low V1Q. The left hemispheric damage group lend to shaw low V1Q. This lowered in was the difference between left hemispheric damage group and negative group. Furthermore, there were no group differences in the PIQ. It is concluded that K-WAIS is effective as evaluator of VIQ mainly of those patients with left hemispheric damage and it is ineffective as a evaluator of PIQ. 3) In the MMPI profile, the both groups displayed high neurotic profiles. There was no difference in the psychotic profiles. The scores of the Depression and Hystery were high in abnormal finding group. This can be seen as one of the lypical findings of chronic head trauma patients. 4) The abnormal finding group tend to be diagnosed as organic mental disorder in the psychological tests more frequently.

• Composites Research
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• v.29 no.1
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• pp.40-44
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• 2016

Nuclear fuel cladding used in a nuclear power plant must possess superior oxidation resistance in the coolant atmosphere of high temperature/high pressure. However, as was the case for the critical LOCA (loss-of-coolant accident) accident that took place in the Fukushima disaster, there is a risk of hydrogen explosion when the nuclear fuel cladding and steam reacts dramatically to cause a rapid high-temperature oxidation accompanied by generation of a huge amount of hydrogen. Hence, an active search is ongoing for an alternative material to be used for manufacturing of nuclear fuel cladding. Studies are currently aimed at improving the safety of this cladding. In particular, ceramic-based nuclear fuel cladding, such as SiC, is receiving much attention due to the excellent radiation resistance, high strength, chemical durability against oxidation and corrosion, and excellent thermal conduction of ceramics. In the present study, cladding with $SiC_f/SiC$ protective films was fabricated using a process that forms a matrix phase by polymer impregnation of polycarbosilane (PCS) after filament-winding the SiC fiber onto an existing Zry-4 cladding tube. It is analyzed the oxidation and microstructure of the metal cladding with $SiC_f/SiC$ composite protective films using a drop tube furnace for thermal shock test.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.419-425
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• 2008

A qualitative and quantitative analytical method was developed for detection of methamphetamine (MA) and its main metabolite amphetamine (AM) in oral fluid. Oral fluids of eleven drug abusers were provided by Police, specimens were collected by stimulation with a cotton swab treated with 20 mg of citric acid ($Salivette^{(R)}$; Sarstedt, USA). As the preliminary test, oral fluid samples were screened for amphetamines by Fluorescence Polarization Immunoassay (TDxFLx, Abbott Co.). Extraction for MA was performed using solid-phase extraction (SPE) by $RapidTrace^{TM}$ (Zymark, USA) with mixed mode cation exchange cartridge, CLEAN $SCREEN^{(R)}$ (130 mg/3 ml, UCT) after dilution with phosphate buffer. Samples were evaporated and derivatized by pentafluoropropionic acid anhydride (PFPA). Quantitation of MA and AM was performed by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring (SIM), the quantitation ions were m/z 204 (MA), 208 (MA-$D_5$), 190 (AM) and 194 (AM-$D_5$). The selectivity, linearity of calibration, limit of detection (LOD) and quantification (LOQ) within- and between day precision, accuracy and recoveries were examined as parts of the method validation. All oral fluid samples gave positive results to immunoassay for MA (cut-off level, 50 ng/ml as d-amphetamine). Concentrations of MA and AM by GC-MS in eleven samples were ranged 104.2${\sim}$4603.3 ng/ml and 32.4${\sim}$268.6 ng/ml, respectively. Extracted calibration curves of MA and AM were linear over the two concentration range of 1${\sim}$100 and 50${\sim}$1000 ng/ml with correlation coefficient of above 0.999. LOQ of MA and AM was 1 and 3 ng/ml, respectively. The intraand inter-day run precisions (CV) for MA and AM were less than 10%, and the accuracies (bias) for MA and AM were also less than 10% at the two different concentrations 5 and 100 ng/ml at low calibration range, 50 and 1000 ng/ml at high calibration range. The absolute recoveries of MA and AM at low and high calibration ranges were more than 82% and 75%, respectively. In this study the qualitative and quantitative analytical method of MA in oral fluid was established. Oral fluid testing may detect drug use in past hours because of its shorter detection window than urine, and be useful in post-accident situations. So oral fluids will be most useful for testing drug abuse in the driving under the influence of drug (DUID) as the alternative specimens of urine.