• 한국수학교육학회지시리즈E:수학교육논문집
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• 제19권4호
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• pp.599-620
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• 2005

There can be two different approaches to introducing Abstract Algebra to undergraduate students: One is to introduce group concept prior to ring concept, and the other is to do the other way around. Although the former is almost conventional, it is worth while to take the latter into consideration in the viewpoint that students are already familiar to rings of integers and polynomials. In this paper, we investigated 16 most commonly used Abstract Algebra undergraduate textbooks and found that 5 of them introduce ring theory prior to group theory while the rest do the other way around. In addition, we interviewed several undergraduate students who already have taken an Abstract Algebra course to look into which approach they prefer. Then we compare pros and cons of two approaches on the basis of the results of the interview and the historico-genetic principle of teaching and learning in Abstract Algebra and suggest that it certainly be one of alternatives to introduce ring theory before group theory in its standpoint.

• 동의생리병리학회지
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• 제27권3호
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• pp.299-305
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• 2013

This study was to evaluate the single dose toxicity of Arecae Semen (AS) in male and female ICR mice. Aqueous extracts of AS (Yield = 13.15%) were administered as an oral dose of 2,000, 1,000 and 500 mg/kg (body weight) according to the recommendation of Korea Food and Drug Administration (KFDA) guidelines. Animals were monitored for the mortality and changes in body weight, clinical signs and gross observation during 14 days after dosing, upon necropsy; organ weight and histopathology of 12 principle organs were examined. We could not find any mortality, clinical signs, and changes in the body and organ weight except for diarrhea. Diarrhea were observed in all three different dosage groups of male mice, and in 2000 mg/kg groups of female mice within 48hrs after administration. In addition, no AS extract related abnormal gross findings and changes in histopathology of principle organs were detected except for some sporadic accidental findings. Although the 50% lethal dose and approximate lethal dose of AS aqueous extracts in female and male mice were detected as over 2,000 mg/kg - the limited highest dosage recommended by KFDA guidelines. It should be carefully used in clinics because AS may be induced severe digestive tract disorders.

• Journal of Power Electronics
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• 제18권5호
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• pp.1536-1544
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• 2018

The existing 24-pulse autotransformer rectifier unit (ATRU) needs interphase reactors for parallel work of the rectifier bridges, and its output voltage cannot be regulated. Aiming at these problems, a step-up and step-down asymmetrical 24-pulse ATRU is proposed in this paper. The connections and turns ratios among transformer windings are well designed. In addition, a 15-degree phase difference is formed between two of the 24 voltage vectors produced by the transformer, which makes the four rectifier bridge groups produce a 24-pulse DC voltage without interphase reactors. Meanwhile, by adding extended winding to each phase of the transformer, wide-range regulation of the ATRU output voltage can be realized, and the reasonable voltage regulation range is between 0.2 and 1.6. The superposition of the voltage vectors and the principle of the voltage regulation are analyzed in detail. Furthermore, the turns ratio of the windings, winding current, output voltage, and kilovolt-ampere rating are all derived. Finally, the simulations and experiments are carried out, and the correctness of the principle and theoretical analysis of the new 24-pulse ATRU are verified.

• 정보처리학회논문지B
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• 제17B권2호
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• pp.99-106
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• 2010

본 논문에서는 검색의 일관성원리와 다중질의 방법을 이용하여 감성을 기반으로 음악을 검색하는 알고리즘을 제안한다. 사용되어지는 특징들은 MPEG-7에서 제공하는 오디오 서술자들이며 이 정보들을 사용하는 것은 국제표준화가 용이 하다는 장점을 가지고 있기 때문이다. 또한 감성에 따라 MPEG-7 오디오 서술자들의 가중치를 부여하는 방법을 제안하여 계산량을 줄이는 방법을 고안하였으며 일관성원리와 다중질의 방법을 사용하는 적합성 피드백을 사용하여 검색의 적합률을 향상시켰다.

• Biomolecules & Therapeutics
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• 제15권2호
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• pp.127-132
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• 2007

The object of this study was to evaluate the acute toxicity of lyophilized water extract of Radix Araliae Cordatae (RA) in male and female mice. The extract was administered to female and male ICR mice as an oral dose of 2000 mg/kg (body wt.) according to the recommendation of KFDA Guidelines. Animals were monitored for the mortality and changes in body weight, clinical signs and gross observation during 14 days after dosing, upon necropsy, organ weight and histopathology of 12 principle organs were examined. As results, we could not find any mortality, clinical signs, changes in the body weight and gross findings except for increases of hypertrophy of lymph nodes in male RA extracts-dosing group. In addition, no RA extracts-treatment related abnormal changes in the organ weight and histopathology of principle organs except for some sporadic accidental findings. The results obtained in this study suggest that the RA extracts does not cause any toxicological signs. The LD$_{50}$ and approximate LD of RA extracts in both female and male mice were considered as over 2000 mg/kg.

• Advances in Energy Research
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• 제4권2호
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• pp.147-161
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• 2016

To start with, finding a sustainable method to produce sweet water and electricity by using renewable energies is one of the most important issues at this time. So, experimental and theoretical analysis of the performance of a closed solar powered still, which is jointed to photovoltaic cells and vacuum pump and equipped by nano plate, as the principle stage of zero discharge desalination process is investigated in this project. Major goal of this work is to reuse the concentrated brine of the Mobin petrochemical complex in order to produce potable, sweet water from effluent saline wastewater and generating electricity in the same time by using solar energy instead of discharging them to the environment. It is observed the increase in brackish water temperature increases the average daily production of solar desalination still considerably. Therefore, the nano plate and vacuum pump are added to augment the evaporation rate. The insolation rate, evaporation rate, the average brackish temperature, ambient temperature, density are investigated during a year 2013. In addition to obtain the capacity of solar powered still, the highest and lowest amount of water and electricity generation are reported during a twelvemonth (2013). Results indicate the average daily production is increased 16%, which represents 7.78 kW.h energy saving comparing with traditional solar still.

• 펄프종이기술
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• 제35권3호
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• pp.43-52
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• 2003

The new principle to measure a sizing degree by a contact angle was developed using an automatic determination of the 3-end point coordinates of the water droplet on a sheet, which could diminish the operator's bias during measurement. A constant amount of water was first placed on a sample sheet by a water dispenser, and then an image of the liquid droplet was captured by a digital camera and then transmitted to a computer. The program measuring for contact angle extracted a liquid contour by Gaussian function combined with a 8-direction chain code. The Euclidean equation was applied to the binary image of the liquid contour in order to measure the diameter of the contour. Finally, the contact angle of the liquid was calculated by using the diameter and the top coordinates. In addition, a surface free energy of the sample sheet and an elapsed time taken up to the complete absorption into the sheet were simultaneously measured with the contact angle.

• 전자공학회논문지CI
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• 제41권4호
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• pp.51-58
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• 2004

본 논문에서는 fault tolerant 하드웨어에서 가장 기본이 되는 온라인 하드웨어 테스트 시스템 구현을 위하여 새로운 인공면역 알고리즘을 제안한다. 인공 면역 알고리즘은 알려진 자기(self) 정보만을 이용하여 항체 즉 tolerance condition을 가장 최적으로 생성하는 알고리즘이다. 이를 위하여 본 논문에서는 생체 면역 시스템의 중요한 원리인 antibody diversity 원리를 적용한 새로운 tolerance condition 생성 알고리즘을 제안한다. 또한 생체 면역 시스템에서의 중요한 세포인 APC (Antigen Presenting Cell)를 Quine-McCluskey 방법으로 구현한 후 유전자 알고리즘을 통해 tolerance condition을 자동 생성하는 알고리즘을 구현한다. 이렇게 제안된 알고리즘은 FSM(Finite State Machine)의 가장 전형적인 예인 십진카운터에 적용한 후 컴퓨터 모의 실험을 통해 그 성능을 확인한다.

• 대한예방한의학회지
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• 제15권2호
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• pp.21-38
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• 2011

Objective : This study was to evaluate the single dose toxicity of Bojungikki-tang(Buzhongyiqi-tang, BJIKT) in male and female mice. Method : Aqueous extracts of BJIKT were administered to female and male ICR mice as an oral dose of 2,000, 1,000 and 500 mg/kg (body weight) according to the recommendation of Korea Food and Drug Administration (KFDA) Guidelines. Animals were monitored for the mortality and changes in body weight, clinical signs and gross observation during 14 days after dosing, upon necropsy ; organ weight and histopathology of 12 principle organs were examined. Results : we could not find any mortality, clinical signs, and changes in the body and organ weight. In addition, no BJIKT-treatment related abnormal gross findings and changes in histopathology of principle organs were detected except for some sporadic accidental findings. Conclusion : The results obtained in this study suggest that the 50% lethal dose and approximate lethal dose of BJIKT aqueous extracts in both female and male mice were considered as over 2,000 mg/kg, the limited highest dosage recommended by KFDA Guidelines, and can be safety used in clinics.

• 동의생리병리학회지
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• 제25권1호
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• pp.122-131
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• 2011

The object of this study was to evaluate the single dose toxicity of Yukmijihwangtanggamibang (YMJHTGMB), a polyherbal formula have been traditionally used as prevention or treatment agent for various lung diseases including chronic obstructive pulmonary disease (COPD), in male and female mice. Aqueous extracts of YMJHTGMB (Yield = 16.33%) wasadministered to female and male ICR mice as an oral dose of 2,000, 1,000 and 500 mg/kg (body weight) according to the recommendation of Korea Food and Drug Administration (KFDA) Guidelines. Animals were monitored for the mortality and changes in body weight, clinical signs and gross observation during 14 days after dosing, upon necropsy; organ weight and histopathology of 12 principle organs were examined. As results, we could not find any mortality, clinical signs, and changesin the body and organ weight except for soft feces restricted to YMJHTGMB 2,000 mg/kg treated two male mice (2/5; 40%) at 1 day after administration. In addition, no YMJHTGMB-treatment related abnormal gross findings and changes in histopathology of principle organs were detected except for some sporadic accidental findings. The results obtained in this study suggest that the 50% lethal dose and approximate lethal dose of YMJHTGMB aqueous extracts in both female and male mice were considered as over 2,000 mg/kg, the limited highest dosage recommended by KFDA Guidelines.