• Korean Journal of Occupational Health Nursing
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• v.6 no.1
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• pp.53-71
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• 1997

Across sectional study was performed to evaluate the chronic effects on central nerve system(CNS) of cumulative exposure of complex organic solvents, using neurobehavioral test. Subjects were 66 (male) dock yard painters of some large ship industry which is located in Ulsan. The neurobehavioral test battery used in this study was NCTB (Neurabehavioral Core Test Battery recommended by WHO(World Health Organization), which consisted of 7 items-Profile of mood states (POMS), Simple reaction time, Santa Ana dexterity test. Digit span, Digit symbol, Benton visual retention test and Pursuit aiming. The subjects were classified by 3 groups according to duration of employment(group 1 ; less than 9 years, group 2 ; 10-14 years, group 3 ; more than 15 years). The results of performance were analyzed considering of work duration, age, educational level, alcohol drinking, smoking and testing time as confounding factors. Benton visual retention test, pursuit aiming correct dot and sum of dot showed significant differences among the groups, and decreased with increasing work duration. It indicated that the mean scores of performance ability were lowering according to work duration. Besides, the tests that didn't show statistical significances but showed linear trends were depression-dejection, vigor, fatigue of POMS, slowest time of simple reaction time and digit span forward. Most of the neurobehavioral test items were correlated with age and educational level. After controlling of confounding factors-age and educational level, the results followed ; digit span backward was different significantly. Tension-anxiety, depression-dejection, anger-hostility of POMS, SD and slowest time of simple reaction time, Santa Ana dexterity test non-preferred hand, digit span forward, Benton visual retention test and pursuit aiming correct dot decreased with increasing of work duration. The correlation analysis was done in order to find out the relationship between subjective symptom and the scores of neurobehavioral core test battery. According to the results of analysis there were no items that had statistical significant relationship(p<0.05).

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1048-1052
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• 2008

Difficulties in developing process of Liquid Crystal Display(LCD) products such as frequent design modifications, various design requirements, and short-term development period bring on the need of integrated design approach that is efficient and easy to handle. Back Light Unit(BLU) of the LCD, which drastically affects the optical performance of LCD products, is divided into in-coupling part and out-coupling part. Serration of the in-coupling part flattens the light received from point light sources and dot pattern of the out-coupling part regularizes the light sent to screen. Therefore, the optical performance of a LCD product is largely influenced by the shape of serration and the arrangement of dot pattern. In this research, a new design approach which enables to improve the optical performance of LCD products and overcome the prementioned difficulties in developing process of LCD products is proposed. The shape of serration is parameterized to 3 parameters and out-coupling part is partitioned into 10 partitions to apply the optimization technique to this problem. 3 parameters for the shape of serration and densities of 10 partitions are used as design variables in the design optimization. Optical simulation tool named SPEOS is used to evaluate the optical performance of the LCD product. Since the optical simulation uses the random ray tracing technique, numerical noise may possibly be included in the simulation process. To solve the problem caused by numerical noise, the PQRSM which can stably find the solution of the noise problem is used in this research.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.375-379
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• 2015

The purpose of this study is to determine the effective energy of a polyenegetic X-ray beam. The half value layer(HVL) of aluminum for 80 kVp X-ray beam was measured by using optically stimulated luminescent nanoDot dosimeters(OSLnDs). The linear attenuation coefficient(${\mu}$) was calculated using the measured HVL. And the mass attenuation coefficient(${\mu}/{\rho}$) was obtained by dividing the linear attenuation coefficient by the density(${\rho}$) of aluminum. The effective energy($E_{eff}$) of the obtained mass attenuation coefficient was determined using data of the X-ray mass attenuation coefficients for photon energies of aluminum given by National Institute of Standards and Technology(NIST). As a result, the HVL value is 2.262 mmAl. The ${\mu}$ value is $3.06cm^{-1}$. The ${\mu}/{\rho}$ value is $1.114cm^2/g$. And the $E_{eff}$ value was determined at 29.79 keV.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.1
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• pp.30-34
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• 2005

This study shows the lasing characteristics of InGaAs/InGaAsP multiple-quantum-well waveguide-type depleted optical thyristor (DOT) using the vertical window. The measured switching voltage and current are 3.36 V and 10 ㎂, respectively. The lasing threshold current is 131 mA at 25 ℃. The output peak wavelength is 1570 nm at a bias current of 1.22 Ith and there is not input signal anymore in the output port. The vertical injection depleted optical thyristor - laser diode (VIDOT-LD) using the vertical-injection structure shows very good isolation between input and output signal.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.236-242
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• 2009

When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible robot arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}$-2C is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed. Lyapunov stability theory is applied to achieve a stable deterministic nonlinear controller for the regulation of joint angle.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.753-756
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• 1992

The piezoelectric ceramics of PMS-PZT was made in the radial mode disk. As the results, in the application of filter required conditions: that is, higher-values for piezoelectric properties($K_p$, $Q_m$) and lower-values for stabilities of $F_{\tau}$(temp. coefficient, aging rate), 5PMS-51PT-44PZ composition statified well. This composition was made in the dot-ring type. Asthe results, with increasing $n^2$ both $Q_m$ and S had high values, decreasing $n^2$ both $K_p$ and BW had low values when the diameter of sintered bodies were constant. Therefore, curve of filter characteristic have sharped with increasing $n^2$ and BW broadened with decreasing $n^2$.

• Journal of the Korean Graphic Arts Communication Society
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• v.2 no.1
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• pp.1-21
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• 1984

Reproduced colors which are half-tone dot printed at the rate of 10, 20, 30, 100% half-tone dot area by each process ink-cyan, magenta and yellow ant at the rate of 10, 20, 30, 100% by the mean color mixing of black, cyan, magenta and yellow, are colorimetric analyzed by make use of the 1931 CIE XYZ system of color specification and matching the Munsell color system. With increased half-tone areas, 1. Yellow has ideal reflectance curve, but magneta has nonideal reflectance curve. 2. Yellow and cyan have almost standard dominant wavelengths but magenta has complementary wavelengths. 3. Yellow has higher excitation purities in primary colors, but low excitation purities in secondary and third colors. 4. Value function is decreased and generally the range of value function in chromaticity diafgram is extented. 5. The properties of black and CMY printed materials have not equality, therefore black process ink is necessery in half-tone printing process.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.3
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• pp.109-120
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• 1998

FM screening has been praised for its apparent resolution advantage over conventional AM screening. FM screening is also known for its criticalness of film output and difficulties in the proofing stage because of the microdot formation. However, FM screening is not a well understood process from press performance point of view. This study was carried out for the purposed of introduction the availability of hifi-offset printing to domestic printing industries and evaluating the print qualities between 300pli AM screen and FM screen with the equivalent sized microdots to 4-5% dot area of the 300lpi AM screen, together with comparing with the 175lpi AM screen representing a conventional printing. Solid density, dot gain, color gamut and some other quality properties were measured and discussed.

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.581-598
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• 1997

This paper is concerned with the impulsive control problem $$ \dot{x}(t) = f(t, x) + g(t, x)\dot{u}(t), t \in [0, T], x(0) = \overline{x}, $$ where u is a possibly discontinuous control function of bounded variation, $f : R \times R^n \mapsto R^n$ is a bounded and Lipschitz continuous function, and $g : R \times R^n \mapsto R^n$ is continuously differentiable w.r.t. the variable x and satisfies $\mid$g(t,\cdot) - g(s,\cdot)$\mid$ \leq \phi(t) - \phi(s)$, for some increasing function $\phi$ and every s < t. We show that the map $u \mapsto x_u$ is Lipschitz continuous when u ranges in the set of step functions whose total variations are uniformly bounded, where $x_u$ is the solution of the impulsive control system corresponding to u. We also define the generalized solution of the impulsive control system corresponding to a measurable control functin of bounded variation.

• Journal of the Korean Society of Costume
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• v.52 no.3
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• pp.111-122
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• 2002

The study of traditional costume is significant in terms of figuring out of the reality of its originality and enrich the costume culture of today. The purpose of this study is to analyze the aesthetic characteristics and to contemplate the aesthetic values of the Kokuryo costume. Kokuryo costume were characterized with the simpleness in its clothing constructions. The spaces found on the dresses were emphasized giving a geometric characteristics and abstract images. Many different colors were used for tops, bottoms, and border elements showing value contrast in each parts of dress. Patterns were simplified in a dot or stripe shapes impling a certain symbols. Dot patterns were varied in its shapes. In general. the decorative elements were simple and eliminated. Through the process of investigating these aesthetic characteristics, aesthetic values were found. The aesthetics of nature were favoured and tradition were respected. Religious mind were favoured and progressive spirit were endowed by the Kokuryo people. They have pursued the diversities and many changes in visual forms of dresses which were the manifestations of their esprit.