• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.358-362
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• 2003

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of HVAC(Heating, Ventilating and Air-Conditioning} for double-deck train. The HVAC system is installed under the roof of carbody. In the lay-out of HVAC system, air duct must be installed to supply air to 1st and 2nd floor respectively. The standard k-epsilon turbulent models and SIMPLEC algorithm based on finite volume method are used to solve the physical HVAC model. To assure convergence, QUICK scheme for momentum equation and the first order upwind scheme for turbulent equations are used. From the results of simulation, the temperature and velocity magnitude are also distributed uniformly in the interior of passenger car.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.805-810
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• 2005

The main functions of suspension system of railway vehicle are isolating vibration from track irregularity to car-body for the Ride quality and keeping its stability with limitation of vehicle's movement. These two functions conflict with each other, then it is impossible to achieve both of performance with traditional passive suspension which has constant characteristics. So, to improve this situation the active suspension was suggested and in specially the semi-active suspension is noticed for its effectiveness on cost despite of its lower performance than full-active suspension. In this study the control logic made through LQG theory was designed with simplified vehicle model and variable damper model defined by $1^{st}$ order system, then the analysis of simulation results was done to understand influence on the performance of semi-active suspension with running conditions and response characteristics of variable damper.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 추계종합학술대회논문집
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• pp.225-228
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• 2000

We propose a new method to deal with the optimized auto-tuning for the PID controller which is used to the process-control in various fields. First of all, in this method, 1st order delay system with dead time which is modelled from the unit step response of the system is Pade-approximated, then initial values are determined by the Ziegler-Nickels method. So deciding binary strings of parents generation using by the fitness values of genetic algorithms, we perform selection, crossover and mutation to generate the descendant generation. The advantage of this method is better than the Ziegler-Nickels method in characteristic of output, and has extent of applying without limit of K, L, T parameters.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.109-112
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• 2000

We propose a new method to deal with the optimized auto-tuning for the PID controller which is used to the process-control In various fields. First of all, in this method, 1st order delay system with dead time which is modelled from the unit step response of the system is Pade -approximated, then initial values are determined by the Ziegler-Nichols method. After inputting constraints of evolution programs, we perform crossover and mutation to generate the descendant generation. The advantage of this method is better than the Ziegler-Nickels method in characteristic of output and has extent of applying without limit of K, L, T.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2647-2662
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• 2014

This paper proposes an efficient and low complexity power-loading algorithm for MIMO-OFDM downlink based cognitive radio system that maximizes the sum rate of single secondary user (SU) under constraints on the tolerable interference thresholds between secondary user and primary user's frequency bands and the total transmission power. Our suboptimal algorithm is based on the $2^{nd}$ order interference tracking and nulling mechanism to allocate transmission power of the subcarriers among SU's scheme. The performance of our proposed suboptimal scheme is compared with the performance of the classical power loading algorithms, e.g., water filling, $1^{st}$ order interference tracking, nulling, and other suboptimal schemes. Numerical results show that our algorithm has low complexity but obtains a higher channel capacity than that of some previous suboptimal algorithms in some scenarios. We dedicate also that for a given interference threshold, the $2^{nd}$ order interference tracking mechanism has dynamic number of nulling position instead fixed number of nulling position.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.99-104
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• 1996

The jet pump is being used in many fields for several purposes because of its simple construction and easy operation. The characteristics of the geometrical variables, pressure gradient and velocity distribution of the jet pump are studied using the CFD technique. The flow calculations through a bended nozzle. a mixing chamber and a venturi are presented and phenomenological aspects are discussed. This study solve 3-D steady incompressible Navier-Stokes equations using the Iterative time marching scheme. The governing equations are differenced with 1st-order accurate backward difference scheme for the time derivatives and 3rd-order accurate QUICK scheme for the convective terms. The Mark-and-cell concept was applied efficiently to solve continuity equation, which is differenced 2nd-order accurate central differenced scheme. The 4th-order artificial damping is added to the continuity equation for numerical stability. A O-type of grid system is generated inside a nozzle and venturi of the jet pump. It has concluded that the results of present study properly agree with physical flow phenomena.

• East Asian mathematical journal
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• 제30권4호
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• pp.405-438
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• 2014

This study analyzed and discussed instruction methods of polyhedrons in elementary mathematics textbook by using the didactic transposition theory. By further segmenting instruction methods, we analyzed the period and order of teaching of polyhedrons, its definitions and presentation methods, and how instruction methods has changed so far. In elementary mathematics textbooks from the 1st to the 2007 revised curriculum, we choose the part where polyhedrons are introduced as the search-target, and analyzed instruction methods in these textbooks by using phenomenological description. The instruction period and order of polyhedrons were systemized when the system of Euclid geometry was introduced, considering the psychological condition of students, and the instruction period and order had been refined according to the curriculum. And methods of definition took into consideration both the academic systems and psychological situations. Also, the subject of learning has changed from textbook and teachers to students. Polyhedrons were connected to real life and students could build up their knowledge by themselves. Constructions were aimed at the understanding of meaning of contents, rather than at itself. Through these analyses, we have some suggestions on the teaching of polyhedrons in the elementary mathematics.

• 대한수의학회지
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• 제45권2호
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• pp.179-183
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• 2005

Epidemiological characteristics of a total of 48 swine herd with diarrhea or a history of diarrhea in Gyeongsang-do between 1999 and 2000 were performed to evaluate the prevalence of Salmonella spp., their serotypes and antibiotic resistance patterns with respect to the different stages of swine production system. A total of 139 Salmonella spp. (21%) were isolated from 662 fecal samples and the overall herd prevalence of Salmonella spp. ranged from 12.5% to 88%. The average prevalence of Salmonella spp. from swine stages of suckling/nursery, grow/finisher and sow stage were 25.7%, 19.2% and 18.4%, respectively. Ten serotypes of Salmonella spp. were identified with a predominance of S. Typhimurium, S. Derby and S. Agona. Twenty-five isolates (18%) were found to be untypable. One hundred and two Salmonella isolates (73.4%) resistant to more than 1 antibiotic were characterized by 24 diverse resistance patterns, and their frequency of antibiotic resistance was highest in grow/finisher stage (83.3%). Resistance to tetracycline (TE; 67.6%), sulfamethoxazole (SU; 46.8%) and streptomycin (ST; 28%) was most common and the most common resistance patterns were TE SU (31.4%), TE (21.6%) and TE SU ST (20.6%) in order.

• 종양간호연구
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• 제7권2호
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• pp.131-139
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• 2007

Purpose: This study was to compare the perceptions about hospice and the meaning of life between the participants and non-participants of the hospice volunteer education program. Method: Descriptive survey research design was used. Participants were 63, and the data collecting period was from October to December, 2006. Instrument developed by Jung-Hee Kim(1990) and Eun-Ja Lee(1998) was modified to measure the perceptions about hospice. To measure the meaning of life, P.I.L (Purpose In Life) instrument by Crumbaugh and Maholick(1969) was utilized. The data were analyzed using $X^2-test$, t-test and Pearson-Correlation Coefficient. Results: 1. The participants in the hospice volunteer education program demonstrated higher perception scores about hospice than the non-participants (t=5.193, p= .001). 2. The program participants also showed higher scores of the meaning of life than non-participants (t=3.084, p=.005). 3. The perception about hospice and the meaning of life had positive correlation (r= .46, p= .01). Conclusion: Therefore, hospice education program must be established in a continual and systematic way in order to standardize the hospice system in Korea.

• 한국응급구조학회지
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• 제5권1호
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• pp.177-198
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• 2001

The purpose of this research which was conducted by surveying the transfer consultation records from 360 medical institutions such as general hospitals, hospitals, clinics to the Emergency Medical Center at E University Hospital for six months(Jan. 1, 2000 - Jun. 30, 2000) are to standardize & complete transfer consultation record of hospitals at the 1st & 2nd referral level and to give patients transferred emergency medical center medical information services on a better quality. The conclusions and suggestions from this study were summarized as follows; (1) Examing the distribution of the referral medical consultation(transfer) sheet type, surgery part local clinic sheet types were 34.4%, medical part local clinic sheet types were 26.7%, undifferentiated local clinic sheet types were 23.9% and hospital level sheet types were 15.0%. (2) The items of the transfer consultation records had been standardized more than 75% in the order of patient's name, date, doctor's name, diagnosis, patient's status, impressions. (3) That the degree of recording completion on these items is in the order of patient's name, date, diagnosis, impressions was revealed. (4) Because the standardization and the degree of recording completion are very low in the patient's gender, age, address, electronic recording system was needed for more perfect input of initial patient informations. (5) This standardizing & complete recording on examination and medication will prevent re-examination and abuse of medication for patients transferred emergency medical center. (6) EMT Transfer System should be fixed in all medical institute for the standardizing & complete recording on care period and departure time will give many emergency patients the proper treatments at the proper time. (7) It was revealed that developing new standardized transfer consultation record & using electronic recording system are needed. (8) The complete recording & Fast Track System were needed for higher rate of bed operation at emergency medical center and more hospital profit.