• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.247-252
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• 2013

An intelligent light emitting diode (LED) dimming system is designed and implemented for energy-saving lighting systems. An LED light bulb is powered by an LED driver controlled by a microcontroller using pulse width modulation (PWM) signals. By changing the duty cycle of the PWM signals, the LED driver generates a driving current of up to 1,000 mA. The current consumption by the LED light bulb exhibits a very linear characteristic that indicates that the level of LED dimming can be finely tuned. Multiple sensors-lighting intensity and ultrasonic range sensors-are combined with the LED dimming system to realize an automatically controllable LED lighting system. The light intensity sensor is capable of sensing ambient light. The ultrasonic range sensor can detect objects from 0.15 to 5.6 m at a resolution of 0.0254 m. The collected information by the light intensity and ultrasonic range sensors is processed by the microcontroller that in turn automatically controls the brightness of the LED light bulb. The algorithm of the software for the LED dimming system is also described.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.73-78
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• 2004

A highly sensitive detecting method has been developed for determining part per billion of sulfur in $H_2S$/Ar plasma. The method is based on the excitation of Ar/$H_2S\;or\;Ar/H_2S/O_2$ mixture in hollow cathode glow discharge sustained by radiofrequency (RF) or 60 Hz AC power and the spectroscopic measurement of the intensity of emission lines from electronically excited $S_2^*\;or\;SO_2^*$ species, respectively. The RF or AC power needed for the excitation did not exceed 30 W at a gas pressure maintained at several mbar. The emission intensity from the $SO_2^*$ species showed excellent linear response to the sulfur concentration ranging from 5 ppbv, which correspond to S/N = 5, to 500 ppbv. But the intensity from the $S_2^*$ species showed a linear response to the $H_2S$ only at low flow rate under 20 sccm (mL/min) of the sample gas. Separate experiments using $SO_2$ gas as the source of sulfur demonstrated that the presence of $O_2$ in the argon plasma is essential for obtaining prominent $SO_2^*$ emission lines.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1630-1641
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• 1995

The dynamic stress intensity factors (DSIF ; $K_{I}$$^{dyn}$) were studied in some polymeric materials using caustics method with a high speed camera system. Also crack tip propagation speed was measured by dynamic crack propagation velocity measuring device. To calculate DSIF a finite element analysis program-INha Stress Analysis Moving CRack(INSAMCR) was utilized. Dynamic fracture characteristics were investigated to verify a relationship between DSIF and crack tip propagation speed and acceleration in PMMA, Homalite-100 and Polycarbonate. The relationship between dynamic stress intensity factor and crack tip velocity revealed typical shapes. Measured crack tip acceleration data envelope converges to the zero level with increasing DSIF. Equivalently crack tip velocities show a wide spread range at low values of DSIF, but become a constant with a higher DSIF. $1.2MPa{\sqrt{m}}$, $1.4MPa{\sqrt{m}}$ and $1.3 MPa{\sqrt{m}}$ were obtained as $K_{I}$$^{dyn}$ values to arrest the dynamic crack for PMMA, Homalite-100 and Polycarbonate, respectively. INSAMCR was run to verify experimental results in PMMA and shows good agreementment.

• East Asian Economic Review
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• v.18 no.1
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• pp.29-54
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• 2014

The purpose of this research is to identify the relation between OFDI (Outward Foreign Direct Investment) and wage inequality. In order to analyze various effects of OFDI on wages depending on the types of workers, the research classified laborers into four categories: permanent/skilled worker, permanent/unskilled worker, temporary/skilled worker, and temporary/unskilled worker. With controlling wage-determining factors such as education, labor union, individual fixed-effect, and industry-level effect, this paper examines whether OFDI attributes to the wage inequality among each type of workers. Moreover, this study also analyzes possible effects on wages that could vary according to the different characteristics of investments by classifying OFDI into two groups: OECD and non-OECD. The results reveal that OFDI makes certain differences according to skill-intensity and contract type in terms of influences on wages. It also shows that the effect of OFDI on wages is more subject to contract type than to skill-intensity. The classification of OFDI into OECD and non-OECD proves that effects on wages can vary by characteristics of the subject of investment.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.201-207
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• 2017

An electron-excited temperature ($T_{ex}$) is not determined by the Boltzmann plots only with the spectral data of $4p{\rightarrow}4s$ in an Ar-plasma jet operated with a low frequency of several tens of kHz and the low voltage of a few kV, while $T_{ex}$ can be obtained at least with the presence of a high energy-level transition ($5p{\rightarrow}4s$) in the high-voltage operation of 8 kV. The optical intensities of most spectra that are measured according to the voltage and the measuring position of the plasma column increase or decay exponentially at the same rate as that of the intensity variation; therefore, the excitation temperature is estimated by comparing the relative optical-intensity to that of a high voltage. In the low-voltage range of an Ar-jet operation, the electron-excitation temperature is estimated as being from 0.61 eV to 0.67 eV, and the corresponding radical density of the Ar-4p state is in the order of $10^{10}{\sim}10^{11}cm^{-3}$. The variation of the excitation temperature is almost linear in relation to the operation voltage and the position of the plasma plume, meaning that the variation rates of the electron-excitation temperature are 0.03 eV/kV for the voltage and 0.075 eV/cm along the plasma plume.

• Journal of fish pathology
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• v.34 no.2
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• pp.169-176
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• 2021

Parasitic infection is among the most common problems for carp cultivation. They are also important for the principal entrance of other hazardous infections as well. This study was carried out for determining of parasitic fauna of two major carp known as silver and grass carp with the comparison of prevalence value and intensity rate of parasites among them, alongside the relationship between the biometric characteristics and host sex with the infection level. For this purpose, a total of 94 fish samples were caught randomly using a fishing net, from Guilan ponds during spring and summer of the year 2018 and transported alive to the laboratory. Upon arriving, the biometric characteristics and genus of each carp were measured individually. Specimens were then acquired from the skin, gills, and eyes of the carp and examined according to standard parasitology methods. Recovered parasites were observed under a light microscope and then fixed for identification. As the result, the occurrence and intensity in the higher length group were comparatively greater than the lower one. Also, the prevalence and intensity of total parasites in male carp were higher than in females. In this research, Dactylogyrus hypophthalmichthys and Dactylogyrus aristhichtys were observed in silver carp and Dactylogyrus lamellatus was detected in grass carp. In the paper below, we found that the host specificity varies in different species of Dactylogyrus isolated from grass carp and silver carp.

• Translational and Clinical Pharmacology
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• v.25 no.1
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• pp.15-20
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• 2017

This study was performed to evaluate the use of vibrating microneedles for the transdermal delivery of vitamin C. The microneedles were designed to vibrate at three levels of intensity. In vitro permeation by vitamin C was evaluated according to the specific conditions such as vibration intensity (levels 1, 2 and 3), application time (1, 3, 5, 7 and 10 min), and application power (500, 700 and 1,000 g). The highest permeation of vitamin C was observed at level 3 of vibration intensity, 5 min of application, and 1,000 g of application power. Vitamin C gel showed no cytotoxic effect against Pam212 cells or skin irritation effects. A pharmacokinetic study of the gel in rats was conducted under optimized conditions. The $AUC_{0-{\infty}}$ and $C_{max}$ increased 1.35-fold and 1.44-fold, respectively, compared with those after vitamin C gel without application with vibrating microneedles. The present study suggests that vibrating microneedles can be used to facilitate the skin permeability of vitamin C under optimal conditions.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.581-588
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• 2018

The purpose of this study was to investigate the relationship among estimated intensity of physical activity, stress response and positive psychological capital. The participants totalled 356 male and female aged 20's~ 50's. Data was collected from 3 Questionnaires and analyzed by descriptive statistics, confirmatory factor analysis, correlation analysis, multiple regression analysis with SPSS and AMOS program. The following conclusions were drawn; First, physical activity had effected on stress response and positive psychological capital. Second, high level physical activity had effected on stress response and positive psychological capital.

• Journal of Korea Trade
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• v.25 no.1
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• pp.133-151
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• 2021

Purpose - This study examines the effects of expatriate transfer on foreign affiliate's labor productivity. Design/methodology - Using Korean-owned foreign affiliate-level data, we estimate the effect of expatriate transfer on foreign affiliate's labor productivity using the system generalized method of moments model. We also consider foreign affiliate- and host country-specific contingencies and test how they are associated with expatriates in enhancing foreign affiliate's labor productivity. Findings - We consider foreign production intensity and cultural distance between the home (i.e., South Korea) and host countries as key contingencies that influence the effect of expatriates on foreign affiliate's labor productivity. We find that expatriates are effective in enhancing the labor productivity of less production-intensive foreign affiliates. This effect is strengthened as expatriates are deployed to countries that share cultural similarities with the home country. Originality/value - Considering that previous studies provide mixed results on the effect of expatriates, our findings suggest that foreign affiliate-specific operational orientation and cultural distance should be considered jointly to understand the true effect of expatriate staffing on foreign affiliate performance.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.1-9
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• 2021

This study was conducted to examine the changes of photosynthesis, growth, chlorophyll contents and functional material contents in light intensity and EC concentration of wild baby leaf vegetable, Indian lettuce (Lactuca indica L. cv. 'Sunhyang') in DFT hydroponics. The cultivation environment was 25±1℃ of temperature and 60±5% of relative humidity in growth system. At 14 days after sowing, combination effect of light intensity (Photosynthetic Photon Flux Density (PPFD 100, 250, 500 µmol·m-2·s-1) and EC level (EC 0.8, 1.4, 2.0 dS·m-1) of nutrient solution was determined at the baby leaf stage. The photosynthesis rate, stomatal conductance, transpiration rate and water use efficiency of Indian lettuce increased as the light intensity increased. The photosynthesis rate and water use efficiency were highest in PPFD 500-EC 1.4 and PPFD 500-EC 2.0 treatment. The chlorophyll content decreased as the light intensity increased, but chlorophyll a/b ratio increased. Leaf water content and specific leaf area decreased as light intensity increased and a negative correlation (p < 0.001) was recognized. Plant height was the longest in PPFD 100-EC 0.8 and leaf number, fresh weight and dry weight were the highest in PPFD 500-EC 2.0. Anthocyanin and total phenolic compounds were the highest in PPFD 500-EC 1.4 and 2.0 treatment, and antioxidant scavenging ability (DPPH) was high in PPFD 250 and 500 treatments. Considering the growth and functional material contents, the proper light intensity and EC level for hydroponic cultivation of Indian lettuce is PPFD 500-EC 2.0, and PPFD 100 and 250, which are low light conditions, EC 0.8 is suitable for growth.