• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.216-219
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• 2002

Conventional piezoelectric lead-zirconate-titanate (PZT) senor has high sensitivity, but it is very brittle. Recently polymer films such as polyvinylidene fluoride (PVDF) have been used use as a sensor. The advantages of PVDF are the flexibility and mechanical toughness. Simple process and possible several shapes are also additional advantages. PVDF sensor can be directly embedded and attached to a structure. In this study, PVDF sensor was embedded in single glass fiber/epoxy composites whereas PZT sensor with AE was attached to single fiber composites (SFC). Piezoelectric sensor responds to interfacial damage of SFC. The signals measured by PVDF sensor were compared to PZT sensor. PZT sensor detected the signals of fiber fracture, matrix crack, interfacial debonding and even sensor delamination, whereas PVDF sensor only detected fiber fracture signals so far, because PZT sensor is much more sensitive than current PVDF sensor. Wave voltage of fiber fracture measured by PVDF sensor was lower than that of PZT sensor, but the results of fast Fourier transform (FFT) analysis were same. Wave velocity using two PZT sensors was also studied to know the internal and surface damage effect of epoxy specimens.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.350-358
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• 2005

Recently, VoIP technology is being accepted as are the most promising Internet telephony service, due to the substitution effect of traditional telephony service. Two standards, i.e, . H.323 and SIP. have emerged for signaling and control for Intemet telephony, of which SIP provides far lower complexity and rich extensibility. It is important to secure components of SIP in order to develop various services. Generally, open source codes provide basic functions of SIP as well as complicated structure, but are difficult to extend. In this thesis, we focused on offering interface mechanism between application and SIP User Agent to easily extend for various VoIP services. This thesis describes what function is needed for SIP User Agent, how to define the internal data structure, and how to define the internal processing procedure. The check iist derived through participating the interoperability event for stabilized SIP User Agent is also suggested.

• Journal of People, Plants, and Environment
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• v.21 no.6
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• pp.485-492
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• 2018

This study aimed to develop and validate highly sensitive determination method of a prostaglandin ($PGE_1$, OP 1206) in human plasma by LC-MS/MS using column switching. Plasma stored at $-30^{\circ}C$ and treated with methanol effectively inhibited interferences synthesized post-sampling. Samples were added with internal standard and were separated by reversed-phase HPLC with a cycle time of 30min. The method was selective for OP 1206 and the regression models, based on internal standard, were linear across the concentration range 0.5-50 pg/mL with the limit of quantification of 0.5 pg/mL (limit of quantitation, LOQ) for OP 1206. The calibration curve of OP 1206 standards spiked in five individual plasma samples was linear ($r^2=0.9999$). Accuracy and precision at the concentrations of 0.5, 1.5, 5.0 and 40 pg/mL, and at the lower LOQ of 0.5 pg/mL were excellent at 20%. OP120 < 6 was stable in plasma samples for at least 24 hours at room temperature, 24 hours frozen at $-70^{\circ}C$, 24 hours in an auto sampler at $6^{\circ}C$, and for two freeze/unfreezing cycles. The validated determination method successfully quantified the concentrations of OP 1206 in plasma samples from simulated administrating a single $5{\mu}g$ OP 1206 formulation. Thus, this novel LC-MS/MS technique for drug separation, detection and quantitation is expected to become the standard highly-sensitive detection method in bioanalysis and to be applied to many low dose pharmaceutical products.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.361-374
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• 1996

In general, a cooling tower has two major noise sources, one is the fan and the other is the falling water. The fan noise is produced by passage of its blades through the air and radiates from the fan stack. Noises from the falling water are caused by splashing and dropping of water cascading over the internal filler of the cooling tower and into the basin and radiate from the louvered face. In this paper, the noise measurements and its frequency analysis are carried out for the locations facing the louvered side and near the fan stack referring the related code and standards in order to study the noise characteristics of the induced-draft cooling tower, especially for the buildings. As a result, it is found that for every doubling of distance from the noise source the noise level decreases by 2~4dBA in the near field with reflect surfaces and decreases by about 6dBA also in the far field without reflect surfaces. As a supplement to the noise measurements, a computer program with simple algorithm is developed in order to estimate the noise level at a distance from the cooling tower, so that the user could apply and modify it for the particular boundary conditions easily.

• Korean Journal of Health Education and Promotion
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• v.29 no.4
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• pp.1-13
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• 2012

Objectives: By analysing the recent trends of published papers in the Korean Journal of Health Education and Promotion, this study aims to identify and discuss some challenging issues, and to provide recommendations for quality improvement of the research papers. Methods: One hundred and sixty five papers published between 2009 and 2011 were examined and categorized according to selected standards. Results are displayed in frequencies and percentages. Results: The volume of articles published has increased by two-folds in three decades since the publication of the first issue. More than 90% of the papers were original articles. Cross-sectional research design was most frequently applied, while only 11.5 % of the articles were intervention studies. For cross-sectional research articles, limitation in generalizability of the study findings was mentioned as one of the major issues, in relation with the frequent use of convenient sampling methods and lack of theoretical evidence in inclusion of variables. Consideration of internal and external validity of the study, utilization of scientific evaluation design and mixed evaluation methods were recommended for intervention research to improve the quality of the research results. Conclusion: To serve as a key resource for evidence-based practices in health promotion, more strict scientific research criteria should be applied to the articles published in the Korean Journal of Health Education and Promotion.

• Preventive Nutrition and Food Science
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• v.3 no.2
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• pp.111-118
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• 1998

To develop a simple, rapid and simultaneous analytical method of phenolic compounds using gas chromatography (GC) and gas chromatography/mass spectrophometer (GC/Ms), this experiment was carried out to search the retention times of capillary columns and the characteristics of fragment ions in electron impact mass spectra. Most of trimethylsilyl derivatives and underivatized phenolic compounds were separated very well on three kinds of capillary columns(HP-1), Ultra-2 and HP-35). Quantitiative determination of phenolic compounds was achieved by internal standards (p-hydroxybenzoic acid iopropyl ester, p-hydroxybenzoic acid ethyl ester). Calibration plts were linear in the investigated range, and the limits of detection were about 5 ng at split mode method. When analyzed by three columns, theseparation times were fairly constant on two nonpolar columns, but a few compounds showed slightly different separation order by the itnermediate polar HP-35 column. The important characteristic patterns of TMS derivatives of phenolic compounds on the EI/MS spectrra appeared at the base peak of [M-15]+ ion and presented at high abundance in most TMS derivatives of phenoloc compounds. [M]+, [M-CH3-COO]+, [M-Si(CH3)4]+ and [M-Si(CH3)4 -CH3]+ also observed in mass spectra of these compounds . Although several compounds have the same retention times on GC column, it might be possible to identify these compounds by the different patternsof mass frgement ions. The TMS derivatives, thus , provide additional information for identification of phenolic compounds in biological systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.255-260
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• 2021

The importance of electric vehicles is gradually increasing due to the recent depletion of fossil fuels. In order to use an electric vehicle, the battery built into the vehicle must be frequently charged. Electric vehicles has very good performance in terms of noise and vibration. However, due to the limitations of the battery, the mileage is considerably shorter than that of an internal combustion engine vehicle once it is charged, and the battery charging time is relatively long compared to the refueling time. There are two types of charging methods for electric vehicle batteries: plug-in and wireless charging. In this paper, we introduced the wireless charging technology for electric vehicles and the current state of technology development and standards in major countries.

• The Korea Journal of Herbology
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• v.23 no.4
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• pp.21-29
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• 2008

Objectives: To determine the standards for discrimination of Magnoliae Cortex, the experiment of specific external-internal characters and the physicochemical pattern analysis were performed. Methods: External characteristics was observed using a stereoscope. Paraffin-mediated sectioned materials were stained by Ju's method. Physicochemical patterns of materials were analyzed using HPLC. Results: 1. Botanical characteristics: Magnolia officinalis had one seed and a white flower, while M. obovata had two seeds and a white flower. Machilus thunbergii had berry and spherical fruits and yellowish green panicles. 2. External characteristics: M. officinalis and M obovata were dark and thick. M. officinalis was gray brown and greasy while M. obovata was light-gray, less oily and smoothly sectioned. Machilus thunbergii was thin and relatively light or yellow-brown, coarsely sectioned and faintly specific scents. 3. Internal characteristics: The bast parts of M. officinalis and M. obovata were commonly wider than Machilus thunbergii The cork cortex of M. officinalis was $10{\sim}mg/L$ cell layers with many oil cells, while that of M. obovata was $4{\sim}7$ cell layers with less oil cells. Machilus thunbergii's xylem which consisted of ring-shaped cambium at 1st and 2nd part was occupied in large portion. 4. Physicochemical pattern: Both M. officinalis and M. obovata involved honokiol and magnolol. All kinds of M. officinalis involved Magnatriol B but one kind of M. ovobata and all of Machilus thunbergii didn't. Machilus thunbergii showed different pattern of chromatogram from that of 2 species above. Conclusions: These results could be used as standards for discrimination of Magnoliae Cortex and as the method of objectification in medicinal herbs giving the basic resource for bioactivity research.

• Journal of the Korean housing association
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• v.25 no.2
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• pp.1-9
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• 2014

This study investigates supply patterns and residential characteristics of the Urban-type Housing in Seoul. There have been 3,336 buildings and 71,790 housing units approved until the end of 2012. One-room apartments and small units less than 30 $m^2$ of residential area amount to 81% and 82% of total units, respectively. Major findings are as follows. First, single- and two-person households less than 30 years of age are mostly lived in the housing. Respondents are mainly professional and white-collar (43%) and service and sales workers (27%). Most of them are mid-income classes (67%), which is twice more than that of single- and two-person households in Seoul. They pay 672 thousand won in rent more than average rent of mid-income class. The rent to income ratios are 29.9% for single households and 24.5% for two-person households, which are higher than that of mid-income bracket. Third, their satisfaction level is relatively high in internal environment and access to public service facilities, but not in external environment and community service facilities. They are satisfied with security and daylight, walking and safety, access to public transport and parking space, but not with noise and vibration, natural environment, access to park and cultural and sports facilities, and most community service facilities. It is necessary to reexamine the articles of deregulation and prepare design standards while considering different housing and locational types.

• Tuberculosis and Respiratory Diseases
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• v.41 no.5
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• pp.531-536
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• 1994

Background: The intrapleural instillation of tetracycline for pleural sclerosis had been most commonly used in patients with symptomatic malignant pleural effusion or recurrent pneumothorax for a long time. Unfortunately, at a time of expanding use of this agent, the production of injectable tetracycline hydrochloride used for pleurodesis was discontinued by its sole manufacturer in mid-1991 because the manufacturer was unable to meet US Food and Drug Administration purity standards. So we performed a preliminary study of doxycycline, as a alternative pleural sclerosant on rabbit pleura and compared its efficacy with that of tetracycline. Method: Eighteen New Zealand white rabbits weighing 2 to 3kg(mean 2.6kg) were devided into three groups. In each groups, one tetracycline(20 mg/ml/kg) and two doxycycline solutions(7 mg/ml/kg and 20 mg/ml/kg) instillated into the right pleural space through an 18-gauge angiocath with care to prevent pneumothorax. All rabbits were sacrificed after 28 days. Results: 1) In the group of tetracycline 20 mg/ml/kg(six rabbits), five rabbits showed partial pleural symphysis with several fibrous bands, and one rabbit died on 22th day. 2) In the group of doxycycline 7 mg/ml/kg(six rabbits), three rabbits showed partial pleural symphysis and the other three rabbits showed complete pleural symphysis without necrosis of underlying parenchymal lung tissue. 3) In the group of doxycycline 20 mg/ml/kg(six rabbits), two rabbits showed complete pleural symphysis without lung necrosis, another two rabbits showed complete pleural symphysis with lung necrosis, and the other two rabbits died on 4th and 13th day, respectively. Conclusion: We concluded that doxycycline is a highly effective sclerosing agent having stronger pleurodesis effect with that of tetracycline by dose base and its optimal dosage was considered as 7 mg/ml/kg with minimal complications.