• Journal of Korean society of Dental Hygiene
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• v.15 no.1
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• pp.55-62
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• 2015

Objectives: The purpose of this study was to investigate the associated factors of self-reported dry mouth in adults. Methods: A self-reported questionnaire was filled out by 249 adults in Seoul and Gyeonggi-do from June to October, 2014. The questionnaire consisted of general characteristics of the subjects, age, monthly income, smoking, alcohol drinking, and systemic diseases including systemic diseases, medication, oral health status, and stress. The question for dry mouth consisted of dryness in skin, eyes, lips, and nasal mucosa. The subjective dry mouth consisted of 6 questions measured by visual analogue scale(VAS). Cronbach's alpha was 0.881 in the study. Oral health related quality of life (OHIP-14) was adapted from Yoon. The questionnaire for OHIP-14 included functional limitation, physical pain, psychological disability, social disability, and experience in hadicap measured by Likert 5 scale. Cronbach's alpha was 0.885 in the study. Data was analyzed for a t-test, one-way ANOVA and multiple regression analysis by using SPSS(SPSS 18.0, USA) program. Results: There were positive correlations between oral health-related quality of life and self-reported dry mouth (functional limitation r=0.288, physical pain r=0.219, psychological discomfort r=0.193, physical disability r=0.280, psychological disability r=0.205, social disability r=0.224 and handicap r=0.270). In the multiple regression analysis, variation of self-reported dry mouth were positively associated with dry eyes{very often(${\beta}=0.305$)), sometimes(${\beta}=0.186$)}, dryness on lips{very often(${\beta}=0.247$), sometimes(${\beta}=0.177$)}, handicap(${\beta}=0.152$), physical disability(${\beta}=0.128$) and alcohol drinking(1-2 times/week)(${\beta}=0.116$) (p<0.001). Conclusions: Self-reported dry mouth may cause deterioration of the entire body dryness(dryness on eyes and lips), low oral health-related quality of life(handicap and physical disability) and alcohol drinking. Thus, It is necessary to develop oral health education programs to prevent and manage dry mouth in adults.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.15.2-22
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• 1995

Evaluating stiffness of near-surface materials has been one of the critically important tasks in many civil engineering works. It is the main goal of geotechnical characterization. The so-called deflection-response method evaluates the stiffness by measuring stress-strain behavior of the materials caused by static or dynamic load. This method, however, evaluates the overall stiffness and the stiffness variation with depth cannot be obtained. Furthermore, evaluation of a large-area geotechnical site by this method can be time-consuming, expensive, and damaging to many surface points of the site. Wave-propagation method, on the other hand, measures seismic velocities at different depths and stiffness profile (stiffness change with depth) can be obtained from the measured velocity data. The stiffness profile is often expressed by shear-wave (S-wave) velocity change with depth because S-wave velocity is proportional to the shear modulus. that is a direct indicator of stiffiiess. The crosshole and downhole method measures the seismic velocity by placing sources and receivers (geophones) at different depths in a borehole. Requirement of borehole installation makes this method also time-consuming, expensive, and damaging to the sites. Spectral-Analysis-of-Surface-Waves (SASW) method places both source and receivers at the surface, and records horizontally-propagating surface waves. Based upon the theory of surfacewave dispersion, the seismic velocities at different depths are calculated by analyzing the recorded surface-wave data. This method can be nondestructive to the sites. However, because only two receivers are used, the method requires multiple measurements with different field setups and, therefore, the method often becomes time-consuming and labor-intensive. Furthermore. the inclusion of noise wavefields cannot be handled properly, and this may cause the results by this method inaccurate. When multi-channel recording method is employed during the measurement of surface-waves, there are several benefits. First, usually single measurement is enough because multiple number (twelve or more) of receivers are used. Second, noise inclusion can be detected by coherency checking on the multi-channel data and handled properly so that it does not decrease the accuracy of the result. Third, various kinds of multi-channel processing techniques can be applied to f1lter unwanted noise wavefields and also to analyze the surface-wavefields more accurately and efficiently. In this way, the accuracy of the result by the method can be significantly improved. Fourth, the entire system of source, receivers, and recording-processing device can be tied into one unit, and the unit can be pulled by a small vehicle, making the survey speed very fast. In all these senses, multi-channel recording of surface waves is best suited for a routine method for geotechnical characterization in most of civil engineering works.

• Proceedings of the Ginseng society Conference
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• 2004.05a
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• pp.17-28
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• 2004

As Korean ginseng is hybrid, an individual variation is very severe, and it takes long times in new breeding because it is required 4 years to pick the seed. But, transformation technique makes the high-functional breeding in short time. The focus of these ginseng studies is to find and secure the useful gene. And it is urgent to accumulate the fundamental data for the molecular breeding and secure the useful genes. Therefore, transformation and soil acclimatization technique are necessary to molecular breeding in use of the introduction of functional genes. In this study, it add to secure of new regulation gene and useful gene as to accumulate the fundamental data for the place where it will contribute to raise the national competitive power. To analyze the useful genes in large scale, we constructed CDNA libraries with various tissues, species, and treated tissue. EST analysis of ginseng perform in large scale and build the EST database of ginseng. We perform the full length sequencing about the selected lots of clones that include the entire open reading frame of the amino acid residues and construct cDNA chip with the parental EST clones. Establishment of the transformation and a soil acclimatization system throuth the re-introduction of the selected ginseng gene that related with the secondary metabolism and anti-stress into the ginseng.

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.327-336
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• 1996

This study was performed to investigate the effec% of immersion in water and thermal cycling on the mechanical peoperties of light cured restorative composite resins. Five commerically available light-cured composite resins(Photo Clearfil A : CA, Lite-Fil A . LF, Clearril Photo Posterior CP, Prisms AP.H.. PA, 2100 : ZH) were unto The specimens of 12 m in diameter and 0.7 m in thickness were made, and an immersion in $37^{\circ}C$ water for 7 days and a thermal cycling of 1000 cycles at 15 second dwell time each in $5^{\circ}C$ and $55^{\circ}C$ baths were performed. Biaxial flexure test was conducted using the ball-on-three-ball method at the crosshead speed of 0.5mm/min. In order to investigate the deterioration of composite resins during the thermal cycling test, Weibull analysis for the biaxial flexure strengths was done. Fracture surfaces and the surfaces before and after the thermal cycling test were examined by SEM. The highest Weibull modulus value of 10.09 after thermal cycling tests which means the lowest strength variation, was observed in the CP group, and the lowest value of 4.47 was obsered in the LF Group. Biaxial flexure strengths and Knoop hardness numbers significantly decreased due to the thermal cycling ($\textit{p}$< 0.01), however, they recovered when specimens were drie4 The highest biaxial flexure strength of 125.65MPa was observed in the ZH group after the thermal cycling test, and the lowest value of 64.86MPa was observed in the CA group. Biaxial flexure strengths of ZH and CP groups were higher than those of PA, CF, and CA groups after thermal cycling test($\textit{p}$< 0.05). Knoop hardness numbers of CP group after the thermal cycling test was the highest(95.47 $\pm$ 7.35kg/$mm^2$) among the samples, while that of CA group was the lowest(30.73 $\pm$ 2.58kg/$mm^2$). Knoop hardness numbers showed the significant differences between the CP group and others after the thermal cycling test(($\textit{p}$< 0.05). Fracture surfaces showed that the composite resin failure developed along the matrix resin and the filler/resin interface region, and the cracks propagated in the conical shape from the maximum tensile stress zone.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.2 s.9
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• pp.99-110
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• 2003

In this study, lightening material weight and normalizing structure of preventing system of landslide soil-rock in trench excavation was tried with focusing in safety construction availability and workability. In other words, risk estimate, safety management method investigation, applicability of bracing material and mechanical stability of bracing structure was studied. From these result, structural stability and structural analysis of light weight bracing structure was carried out with common structural analysis program, for examining movement mechanism of bracing structure and normalization of standard. The result are summarized as following. (1) Mechanical ability of bracing members and soil pressure parameter acting to member for ensuring mechanical propriety of bracing structural and useful of new material considering soil mechanics boundary were proposed. Also theory and method of analysis of bracing structural were proposed. (2) As a result of the structure analysis of geographical profile for light pannel used FRP as hard clay mechanical characteristics(bending moment, shear force, axial force) of panel were changed according to groundwater level and it is proved that the result of mechanical analysis is within allowable stress. Thus, light pannel is available for bracing structure in trench excavation.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.16-28
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• 2013

Recently the various applications and spectral indices development of airborne hyperspectral imagery(A-HSI) has been increased. Especially the vegetation indices (VIs) were used to verify stress and vigor of vegetation. The VIs needs two or more spectral bands selectively to calculate as NIR(near infrared) and red wavelength. The A-HIS has specific band characteristics as narrow, continues and many. The A-HIS has narrow, continues and many specific band characteristics. That could be make it confuse which of bands could be explained for appropriate vegetation characteristics. If the A-HIS bands is not the same the wavelength with VIs' development band setting, then it need a selection adequate for spectral characteristics of target vegetation. Therefore we set 4 substitute bands for NIR and red wavelength respectively and calculated two VIs combined with substitute bands such as NDVI(normalized difference vegetation index) and MSRI(modified simple ratio index). To consider the variation of each VIs, we adapted the image differencing method of change detection technique. Also, we used spectral derivative to identify appropriate bands for spectral characteristics of digital forest cover type map. The result of adequate bands for two VIs selected red #3 as 680.2nm and NIR #2 as 801.7nm. This wavelength was good for any forest type in low variations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.819-824
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• 2016

The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 33.64 and 67.27 days at 110[$^{\circ}C$], equivalent to 40 and 80 years of aging at 50[$^{\circ}C$], respectively. These samples were referred to as CSPE-0y, CSPE-40y and CSPE-80y, respectively. As the accelerated thermally aged years of the CSPE increase, the insulation resistance[$\Omega$] at 20[Hz], 500[Hz], and 2[KHz], and the percent elongation [%EL] of the CSPE decrease. However, the dissipation factor($tan{\delta}$) at 20[Hz], 500[Hz], and 2[KHz], the apparent density[$g/cm^3$], the glass transition temperature and the melting temperature of the CSPE were increased. The period of time that the voltage has to be applied until electric breakdown of the CSPE-0y is longer than that of the CSPE-40y, and the CSPE-80y, but the dielectric strength of the CSPE-80y is lower than that of the CSPE-0y and the CSPE-40y. The differential temperatures after the AC and DC voltages are applied to CSPE-0y, CSPE-40y and CSPE-80y are 0.026~0.028[$^{\circ}C$], 0.030~0.042[$^{\circ}C$], 0.018~0.045[$^{\circ}C$], respectively. The variations of temperature for the AC voltage are higher than those for the DC voltage when an AC voltage is applied to CSPE-0y, CSPE-40y and CSPE-80y. It is found that the dielectric loss owing to the dissipation factor[$tan{\delta}$] is related to the electric dipole conduction current. It is ascertained that the ionic (electron or hole) leakage current is increased by the separation of the branch chain of CSPE polymer from the main chain of the polyethylene as a result of thermal stress due to accelerated thermal aging as well as by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$ after seawater soaking.

• KIEE International Transaction on Systems and Control
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• v.2D no.2
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• pp.78-91
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• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.367-375
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• 2014

In numbers of kinds of heat exchanger, the shell-tube heat exchanger is the most commonly used type of heat exchanger in the industry field. In order to improve the thermal performance of the heat exchanger, this study was analyzed heat transfer characteristics according to arrangement of baffle and direction of baffle and bump phase of baffle about shell-tube heat exchanger using appropriate SST (Shear Stress Transport) turbulence model for flow separation and boundary layer analysis. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of shell side was constantly 344 K and the variation of the water flow rate was 6, 12, 18 and 24 l/min. As the result of analysis, zigzag baffle arrangement enhances heat transfer rate and pressure drop. Furthermore, in the direction of the baffle, heat transfer rate is more improved with vertical type and angle $45^{\circ}$ type than existing type, and pressure drop was little difference. Also, the bump shape of baffle surface contributes to heat transfer rate and pressure drop improvement due to the increased heat transfer area. Through analysis results, we knew that the increase of the heat transfer was influenced by flow separation, fluid residual time, contact area with the tube, flow rate, swirl and so on.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.277-288
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• 2015

This study aims to identify determinants affecting on geographic variations in the prevalence of arthritis in Korean women using data mining. Data from Korean Community Health Survey 2012 with 249 small districts were analyzed. Socio-demographic, health behavior and status, and morbidity status measures were analyzed using conventional regression model and convergence analysis method such as decision tree for convergence analysis. Rate of workers in agriculture, forestry, and fishing, salaried workers, persons higher than high school graduates, non-treatment of needing care, non-treatment of care because of economic reason, obesity, heavy drunkers, complaining persons of chewing difficulty, persons with experiencing depression, persons with perceiving stress, and persons with diagnosing hypertension and angina pectoris were variation determinants of prevalence of arthritis in 249 small districts and these districts were classified 10 area groups by decision tree model. Our finding suggest that the approach based characteristics by small area groups rather than national wide or individual level would be effective to reduce in variations of prevalence of arthritis.