• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.330-338
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• 2018

The proportional-integral-derivative(PID) controller has been widely used in the industry because of its robust performance and simple structure in a wide range of operating conditions. However, the AVR(Automatic Voltage Regulator) as a control system is not robust to variations of the power system parameters. Therefore, it is necessary to use PID controller to increase the stability and performance of the AVR system. In this paper, a novel design method for determining the optimal PID controller parameters of an AVR system using the particle swarm optimization(PSO) algorithm is presented. The proposed approach has superior features, including easy implementation, stable convergence characteristic and good computational efficiency. In order to assist estimating the performance of the proposed PSO-PID controller, a new performance criterion function is also defined. This evaluation function is intended to reflect when the maximum percentage overshoot, the settling time are given as design specifications. The ITAE evaluation function should impose a penalty if the design specifications are violated, so that the PSO algorithm satisfies the specifications when searching for the PID controller parameter. Finally, through the computer simulations, the proposed PSO-PID controller not only satisfies the given design specifications for the terminal voltage step response, but also shows better control performance than other similar recent studies.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.270-276
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• 1997

This experiment was conducted to develop a practical method to growth in hydroponics conditions. For this purpose, leaf lettuce (Lactuca sativa L., cv. 'Cheongchima') was cultivated under different temperature and light conditions in experimental fields of Sahmyook university from March, 1991 to May, 1996. The visual quality score(VQS), a quantitative parameter to evaluate harvested leaf lettuce quality. The leaf lettuce cultivated at $25^{\circ}C$ solution temperature showed the highest fresh weight pe, plant (59.7g/plant), but lowest visual quality score (5.2), while leaf lettuce cultivated at 15$^{\circ}C$ solution temperature showed lower fresh weight per plant (25.2g/plant) but highest visual quality score (7.2). In general, growth of leaf lettuce was retarded by low solution temperature, but quality was higher than those of other solution temperature. Different day/night temperature of nutrient solutions 20/2$0^{\circ}C$ and 25/2$0^{\circ}C$ was highest in yield, but leaf type was grow longer, and visual quality are inferior to low temperature. Yield was decreased as 10 and 25% at 60 and 80% shading treatment, respectively. Chlorophyll content was decreased by shading. but plant height and root length were increased of leaf lettuce growth with hydroponics.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.135-146
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• 2015

To provide the data necessary to determine the design wind speed for calculating the wind load acting on a greenhouse, we measured the wind speed below 10m height and analyzed the power law exponents at Buan and Gunwi. A wind speed greater than $5m{\cdot}s^{-1}$ is appropriate for calculating the power law exponent necessary to determine the wind speed distribution function according to height. We observed that the wind speed increased according to a power law function with increased height at Buan, showing a similar trend to the RDC and JGHA standards. Therefore, this result should be applied when determining the power law function for calculating the design wind speed of the greenhouse structure. The ordinary trend is that if terrain roughness increases the value of power law exponent also increases, but in the case of Gunwi the value of power law exponent was 0.06, which shows contrary value than that of the ordinary trend. This contrary trend was due to the elevations difference of 2m between tower installed and surrounding area, which cause contraction in streamline. The power law exponent started to decrease at 7 am, stopped decreasing and started to increase at 3 pm, and stopped increasing and remained constant at 12 pm at Buan. These changes correspond to the general change trends of the power law exponent. The calculated value of the shape parameter for Buan was 1.51, confirming that the wind characteristics at Buan, a reclaimed area near the coast, were similar to those of coastal areas in Jeju.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.609-613
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• 2009

This study was conducted to investigate the effects of dietary supplementation of $\beta$-1,3 glucan on growth, hematological and body composition in juvenile korean rockfish, Sebastes schlegeli fed the white fish meal based diets for 6 weeks. Four experimental diets were formulated to contain control (without supplementation of glucan), 0.05%, 0.1% and 0.5% (this diet was fed to fish daily, bi-weekly as three different dietary treatments) $\beta$-1,3 glucan per kg diet (Control, $D_{0.05}$, $D_{0.1}$, $D_{0.5}$, $B_{0.05}$, $B_{0.1}$, $B_{0.5}$). Fish averaging $4.0\pm0.1g$ (mean$\pm$SD) were randomly distributed in each aquarium as triplicate groups of 23 fish. Weight gain (WG, %) and specific growth rate (SGR, %) of fish fed $D_{0.5}$ diet were significantly lower than those of fish fed the other diets (P<0.05). Feed efficiency (FE) of fish fed $B_{0.05}$ diet was significantly higher than those of fish fed $D_{0.1}$, $D_{0.5}$, $B_{0.1}$ and $B_{0.5}$ diets (P<0.05). Protein efficiency ratio (PER) of fish fed $B_{0.05}$ diet was significantly higher than those of fish fed $D_{0.1}$ and $D_{0.5}$ diets (P<0.05). According to the results, the supplementation of 0.05% $\beta$-1,3 glucan daily and/or biweekly is optimum in juvenile Korean rockfish.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1072-1081
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• 2012

For Ka-band satellite communication system, a new flexible payload technologies which can compensate rain attenuation have to be developed. The Ka-band satellite output power control technology enables to adjust downlink output power of satellite payload in Ka-band (19.8 ~ 22.2 GHz). In this paper, we introduce multi-beam antenna with multi-port amplifiers for Ka-band flexible output power allocation system. We have designed multi-beam antenna with array-fed reflector to form 8 beams on the Korean Peninsula. The target EIRP per beam is more than 59 dBW. The system is designed to present 6 dB boost beams for rainfall areas. Individual beams were optimized by the excited amplitude and phase of feed elements of the feed cluster. The multi-port amplifier(MPA) is one of effective approaches for flexible power allocation in combination with multi-beam antenna. In case of using MPA in multi-beam system, the inter-port isolation characteristic of MPA is important parameter to avoid interference among the output ports. In this paper, we propose a new MPA structure that consists of two $4{\times}4$ Buttler matrixes and phase/amplitude controllable power amplifier modules.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.486-494
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• 2003

When the orientations of joints are measured on a rock exposure, there are frequent cases that are difficult to approach by the surveyor to the target joints or to set up scanlines on the slope. In this study, to complement such limit and weak points, a new algorithm was developed to interpret joint orientation from analyzing the images of rock slope. As a method of arranging the multiple images of a rock slope, the multistage convergent photographing system was introduced to overcome the limitation of photographing direction which existing method such as parallel stereophotogrammetric system has and to cover the range of image measurement, which is the overlapping area between the image pair, to a maximum extent. To determine camera parameters in the perspective projection equation that are the main elements of the analysis method, a new method was developed introducing three ground control points and single ground guide point. This method could be considered to be very simple compared with other existing methods using a number of ground control points and complicated analysis process. So the global coordinates of a specific point on a rock slope could be analyzed with this new method. The orientation of a joint could be calculated using the normal vector of the joint surface which can be derived from the global coordinates of several points on the joint surface analyzed from the images.

• Journal of Ginseng Research
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• v.24 no.1
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• pp.46-50
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• 2000

This study was carried out to investigate the effect of crude saponin from Korean red ginseng on clinical chemical parameters in ovariectomized rats. The crude red ginseng saponin was prepared by Diaion HP-20 adsorption chromatography and spirit. Tota1 of 50 rats were divided into 5 groups: normal control (NC), sham-ovariectomized (SO), ovariectomized (OR), ovariectomized and saponin treated (OS) and normal control treated with saponin (NS). Saponin was intraperitonally administered for 12 weeks since 1 week before ovariectomy: The body weight of ovariectomized rats showed no significant change but that of NS group showed significant increase when compared with NC group. Platelet counts of serum showed significant increase when treated with saponin regardless of ovariectomy. Triglyceride content of serum in NC group was 152.1 mg/㎗, while that of OR group was decreased to 99.9 mg/㎗ However, when saponin was administered, the content was increased to 138.0 mg/㎗. The weight of spleen also showed significant increase when treated with saponin, while the other organs showed no weight changes. On the other hand, ovariectomy in rats induced decrease in femur weight by 10% when compared with NC group. However, administration of crude saponin in ovariectomized rats recovered the weight of the femur to the similar level of NC (e<0.01 0.05). In addition, femur weight of NS group indicated 10 to 16% higher value than that of NC. These results suggest that Korean red ginseng saponin attenuates phyiological disorders induced by malfunction of ovary.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.387-392
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• 2018

The aim of this study was to determine the statistical significance of heart rate variability(HRV) between sleep stages, Apnea-hypopnea index(AHI) and age in patients with obstructive sleep apnea(OSA). This study evaluated the main parameters of HRV over time domain and frequency domain in 40 patients with sleep apnea. The non-REM(sleep stage) was statistically validated by comparing the AHI degree of the three groups(mild, moderate, severe) of sleep apnea patients. The NN50(p=0.043), pNN50(p=0.044), VLF peak(p=0.022), LF/HF(p=0.028) were statistically significant in the R-R interval of patients with sleep apnea from the control group (p<0.05). The LF / HF (p = 0.045) and HF power (p = 0.0395) parameters between the non-RAM sleep (sleep 2 phase) and REM sleep in patients with sleep apnea were statistically significant in the control group(p<0.05). We may be able to provide a basis for understanding the correlation among AHI, sleep stage and age and heart rate variability in patients with obstructive sleep apnea.

• Journal of Korean Society of Forest Science
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• v.99 no.6
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• pp.878-884
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• 2010

Ozone sensitivity of physiological indicators and the difference of ozone tolerance on 4 families of Quercus aliena seedlings were investigated on the basis of the standardized physiological indicators. Photosynthetic parameters, photosynthetic pigment and malondialdehyde (MDA) content, and antioxidative enzyme activities were measured or analyzed from the leaves of Q. aliena seedlings at the end of ozone fumigation, and ozone tolerance indices among 4 families were calculated with the standardized physiological parameters. After ozone treatment, the reduction of carboxylation efficiency was observed in the leaves of four families, and their reduction were ranged from -24.1% to -56.9% of control seedlings. Photosynthetic pigment content differed significantly among 4 families and treatments. The reduction of total chlorophyll content showed the highest in family SU4 (-40.6%) and the lowest family US2 (-18.8%). Ascorbate-peroxidase (APX) activity showed significant difference among families and treatments, and increased as compared with control in three families, except for family US2. On the basis of the physiological indices, ozone tolerance of four families was ranked in the order of US1 > SU4 > US2 > SU1. In conclusion, photosynthetic parameters, pigment content and APX activity were recommended as appropriate indicators to assess the tolerance against ozone stress of Q. aliena.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.258-267
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• 2017

The price competitiveness of photovoltaic system (PV system) has risen recently due to the growth of industries, however, it is rarely applied to the greenhouse compared to other renewable energy. In order to evaluate the application of PV system in the greenhouse, power generation and optimal installation area of PV panels should be analyzed. For this purpose, the prediction of the heating and cooling loads of the greenhouse is necessary at first. Therefore, periodic and maximum energy loads of a multi-span greenhouse were estimated using Building Energy Simulation(BES) and optimal installation area of PV panels was derived in this study. 5 parameter equivalent circuit model was applied to analyzed power generation of PV system under different installation angle and the optimal installation condition of the PV system was derived. As a result of the energy simulation, the average cooling load and heating load of the greenhouse were 627,516MJ and 1,652,050MJ respectively when the ventilation rate was $60AE{\cdot}hr^{-1}$. The highest electric power production of the PV system was generated when the installation angle was set to $30^{\circ}$. Also, adjustable PV system produced about 6% more electric power than the fixed PV system. Optimal installation area of the PV panels was derived with consideration of the estimated energy loads. As a result, optimal installation area of PV panels for fixed PV system and adjustable PV system were $521m^2$ and $494m^2$ respectively.