• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.31-39
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• 2013

This paper presents small signal stability analysis of a doubly fed induction generator (DFIG) based wind farm including series dynamic braking resistor (SDBR) connected at the stator side. A detailed mathematical model of wind turbine, DFIG machine and converters and SDBR is presented in this paper to derive the complete dynamic equations of the studied system. Small signal stability of this system is carried out by modal and sensitivity analysis, participation factors and eigenvalue analysis. Finally, this paper presents an analysis of the dynamic behavior of DFIG based wind farm under voltage dip condition with and without SDBR.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.173-174
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• 2016

This paper proposes a comparison of Voltage Oriented Control (VOC) and Direct Power Control (DPC) under command mode transition for PMSG Wind Turbines (WT). Based on a neutral point clamped three level back to back type Voltage Source Converter (VSC), proposed control scheme automatically control the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. Automatic command mode transition based on the dc-link voltage error provides a command mode changing between grid command and MPPT mode. It is confirmed through PLECS simulations in Matlab. Simulation result shows that proposed control scheme of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control scheme of MPPT with optimal torque control and VOC under a step response. The proposed control scheme makes it possible to provide a good dynamic performance for PMSG wind turbines in order to generate a high quality output power.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.468-471
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• 2005

The Air Quality Sensor(AQS), located near the fresh air inlet, serves to reduce the amount of pollution entering the vehicle cabin through the HVAC(heating, ventilating, and air conditioning) system by sending a signal to close the fresh air inlet door/ventilation flap when the vehicle enters a high pollution area. One chip sensor module which include above two sensing elements, humidity sensor and bad odor sensor was developed for AQS (air quality sensor) in automobile. With this sensor module, PIC microcontroller was designed with back propagation neural network to reduce detecting error when the motor vehicles pass through the dense fog area. The signal from neural network was modified to control the inlet of automobile and display the result or alarm the situation. One chip microcontroller, Atmega128L (ATmega Ltd., USA) was used. For the control and display. And our developed system can intelligently detect the bad odor when the motor vehicles pass through the polluted air zone such as cattle farm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.780-790
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• 2015

Studies for a plants factory is progressing for cultivating various plants by the needs of the times and industry around world. However most studies is carried out only in lab sized plants factory. It does not consider an economic feasibility. The study for a large scale plants factory is very required to get an economic gain. In this paper we has been studying a smart farm factory based on ICT using the hydroponics ginseng. The smart farm factory is to extend a concept of the general plants factory to full automated factory. The factory can collect the information about growing of plants and automate operating and management of factory like the existing plants factory. Also it is the total plants factory management system, which analyzes the collected information for optimized growth and development of plants and applies the result to the system back.

• Journal of Veterinary Science
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• v.21 no.6
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• pp.82.1-82.10
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• 2020

Background: The clinical presentation of horses with back pain (BP) vary considerably with most horse's willingness to take part in athletic or riding purpose becoming impossible. However, there are some clinical features that are directly responsible for the loss or failure of performance. Objectives: To investigate the clinical features of the thoracolumbar region associated with BP in horses and to use some of the clinical features to classify equine BP. Methods: Twenty-four horses comprised of 14 with BP and 10 apparently healthy horses were assessed for clinical abnormality that best differentiate BP from normal horses. The horses were then graded (0-5) using the degree of pain response, muscular hypertonicity, thoracolumbar joint stiffness and overall physical dysfunction of the horse. Results: The common clinical features that significantly differentiate horses with BP from non-BP were longissimus dorsi spasm at palpation (78.6%), paravertebral muscle stiffness (64.3%), resist lateral bending (64.3%), and poor hindlimb impulsion (85.7%). There were significantly (p < 0.05) higher scores for pain response to palpation, muscular hypertonicity, thoracolumbar joint stiffness and physical dysfunction among horses with BP in relation to non-BP. A significant relationship exists between all the graded abnormalities. Based on the cumulative score, horses with BP were categorized into mild, mild-moderate, moderate and severe cases. Conclusions: BP in horse can be differentiated by severity of pain response to back palpation, back muscle hypertonicity, thoracolumbar joint stiffness, physical dysfunctions and their cumulative grading score is useful in the assessment and categorization of BP in horses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.622-629
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• 2014

This study induced biological denitrification and nitrification via a biofiltration process with the view of removing nitrogen from land-based fish farm effluent. To achieve this, we operated an aquaculture nitrogen-removal system that includes a denitrification and nitrification reactor [working volume 40 L, flow rate 64.8 L, HRT (hydraulic retention time) 14.8 h, HRT considering recycling of NOx 7.4 h]. In the continuous process, the nitrification rate of ammonium nitrogen exceeded 90% at a steady state and the denitrification efficiency exceeded 80% with recycling to a pre-anoxic reactor. In addition, the pH in the final effluent was lower with a low influent water alkalinity averaging 100 mg/L (as $CaCO_3$). For effective denitrification reactions, carbon must be supplied via particulate organic matter (POM) hydrolysis because of the low C/N (carbon/nitrogen) ratio in the water.

• Sijohaknonchong
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• v.44
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• pp.57-74
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• 2016

This these studies on SiJo to be published Dongkwang magazine. Dongkwang magazine was published from 1926 to 1933 but in the concrete it proceeded for three years two month. It was published a little SiJo and SiJo would reflected a phenomenon of society and a character of literature. A representative characters of the Si-Jo in substance at that time was summed up three. First it described a warmth of farm village. Expecially make full use of a sensuous description expressed a landscape of farm village. Otherwise it revealed a life of austerity in farming area. Second it reflected a phenomenon of return to their home village. People who was familiar with their country loved to come back their old home. To relax their mind and body they came back home and they pursuit romantic life. Third it was a poetry of historical retrospect. Although their country was colonial situation they longed fot their country's independence. Because of this anxiety they expressed their heart by means of old sijo. Mainly using old castle, ring, historic site they revealed a hidden feelings thst they had. It was a sorrow, an eager, remembrance etc. In spite of a poor surroundings they sang hope, romance, an possibility of independence. and so SiJo reflected the phases of the times.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.569-577
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• 2000

The position of tobacco leaves is affluence to the quality. To evaluate its quality, sample leaves was collected according to the position of attachment. In Korea, the position was divided into four classes such as high, middle, low and inside positioned leaves. Until now, the grade of standard sample was determined by human expert from korea ginseng and tobacco company. Many research were done by the chemical and spectrum analysis using NIR and computer vision. The grade of tobacco leaves mainly classified into 5 grades according to the attached position and its chemical composition. In high and low positioned leaves shows a low level grade under grade 3. Generally, inside and medium positioned leaf has a high level grade. This is the basic research to develop a real time tobacco leaves grading system combined with portable NIR spectrum analysis system. However, this research just deals with position recognition and grading using the color machine vision. The RGB color information was converted to HSI image format and the sample was all investigated using the bundle of tobacco leaves. Quality grade and position recognition was performed through well known general error back propagation neural network. Finally, the relationship about attached leaf position and its grade was analyzed.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.238-248
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• 2016

In this study, an automatic command mode transition strategy of direct power control (DPC) is proposed for permanent magnet synchronous generators (PMSGs) medium-voltage (MV) offshore wind turbines (WTs). Benchmarking against the control methods are performed based on a three-level neutral-point-clamped (NPC) back-to-back type voltage source converter (VSC). The ramping rate criterion of complex power is utilized to select the switching vector in DPC for a three-level NPC converter. With a grid command and an MPPT mode transition strategy, the proposed control method automatically controls the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. The automatic command mode transition strategy of DPC is confirmed through PLECS simulations based on Matlab. The simulation result of the automatic mode transition strategy shows that the proposed control method of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control methods of MPPT and VOC under a step response. The proposed control method helps provide a good dynamic performance for PMSGs MV offshore WTs, thereby generating high quality output power.

• Journal of Animal Science and Technology
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• v.53 no.4
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• pp.325-332
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• 2011

This research was conducted to analyze the effects of raising farm on the heritability and breeding values of Hanwoo cows for their carcass traits, including cold carcass weight (CWT), back-fat thickness (BFT), eye-muscle area (EMA) and marbling score (MAR). The carcass data and pedigree data were collected from steers raised on Hanwoo farms in Pyeongchang-gun, Gangwon-do, South Korea. Three analytical models were applied for the estimation of heritabilities and breeding values. The first model (model 1) included slaughter house-year-month combination as fixed effects and age at slaughter was fitted as linear and quadratic covariates. The second model (model 2) was similar to model 1, but raising farm was additionally included as random effect. The third model (model 3) was similar to model 1 but farm effects were additionally included as fixed effect. The comparisons between the model 1 and the models including farm effect (model 2 and model 3) revealed that heritability estimates from model 2 or model 3 were smaller to those from model 1 for all carcass traits. Especially, obvious decrease of heritability was observed in CWT where heritability was 0.23 from model 1, 0.15 from model 2 and 0.18 from model 3. The maximum log likelihood of the model 2 and 3 were higher than those of model 1 for all traits. In model 2 that raising farm was included as a random effect, the ratio of farm variance to the total phenotypic variance were ranged from 4% (EMA) to 18% (CWT). Top 10% and bottom 10% of female cows were selected based on the breeding values from model 1, and the Spearman's rank correlation coefficients among models were estimated for each trait within selected group. The correlation coefficients were ranged from 0.57 to 0.95 in top 10% group and from 0.68 to 0.95 in bottom 10% group. These results show that the discrepancies in the rankings of breeding values can be based on the models applied. In conclusion, the results obtained in this study suggest that the herd effect or farm effect should be included in the analytical model when breeding values are estimated with the purpose of improvement of carcass traits of Hanwoo breeding cows.