• 조명전기설비학회논문지
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• 제25권8호
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• pp.48-59
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• 2011

This paper presents a new gain scheduling speed controller of permanent magnet synchronous generators(PMSG) for MW-class direct-driven wind turbine systems. The proposed gain scheduling speed controller performs the speed tracking at more than one operating point, and the first-order torque observer estimates the turbine torque which is needed to precisely control the speed of PMSG. The proposed speed controller verifies that the PMSG can successfully follow the reference speed which is determined via the maximum power point tracking(MPPT) control and pitch control under turbulent wind conditions. The proposed speed control algorithm is simulated using Simulink and its performance is confirmed through comparison with the results by PI control method.

• Journal of Power Electronics
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• 제6권2호
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• pp.114-120
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• 2006

This paper compares two types of direct torque controllers for permanent magnet synchronous motors(PMSMs). These controllers both use a single-chip FPGA(Field Programmable Gate Array) but have differing hardware configurations. One of the controllers was constructed by programming a soft-core CPU and hardware logic circuits written in VHDL(Very high speed IC Hardware Description Language), while the other was constructed of only hardware logic circuits. The characteristics of these two controllers were compared in this paper. The results show the controller constructed of only hardware logic circuits was able to shorten the control period and it was able to suppress the low torque ripple.

• 한국정보처리학회논문지
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• 제6권12호
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• pp.3613-3621
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• 1999

본 논문에서 우리는 프로토콜의 체계적 설계를 위해 이산대수에 기반한 키분배 프로토롤의 안전성을 분석하였다. 또한, Diffie-Hellman 문제를 이용하여 기존의 Station-to-Station 프로토콜 보다 효율적인 키동의 프로토콜을 제안한다. 제안한 프로토콜은 분석된 안전성을 만족하고, 직접적인 인증을 제공하도록 설계되었다.

• 한국응급구조학회지
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• 제19권2호
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• pp.29-38
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• 2015

Purpose: The purpose of this study was to improve airway management ability by comparing the speed, angle of the neck, and confidence and ease of supraglottic airway laryngopharyngeal tube (SALT) and endotracheal intubation via direct laryngoscopy. Methods: The subjects of this experimental research study with a randomized crossover design were 44 emergency medicine technician - paramedics working in the fire department of 'J' - do. SPSS version 19.0 was used in the statistical analysis. Results: Speed and angle of the neck (p<.001), as well as confidence and ease (p<.001), showed significant differences between endotracheal intubation with a SALT and endotracheal intubation via direct laryngoscopy. Conclusion: If endotracheal intubation via direct laryngoscopy is difficult to use or in trauma patients, using a SALT is safe and enables fast intubation. Moreover, in order to improve the efficiency of advanced airway management, the application of SALT should be introduced in the domestic scene.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3130-3139
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• 2022

Direct containment heating (DCH) is one of the potential factors leading to early containment failure. DCH is closely related to safety analysis and containment performance evaluation of nuclear power plants. In this study, a DCH prediction program was developed to analyze the DCH loads of containment vessel. The phenomenological model of debris dispersal, metal oxidation reaction, debris-atmospheric heat transfer and hydrogen jet burn was established. Code assessment was performed by comparing with several separate effect tests and integral effect tests. The comparison between the predicted results and experimental data shows that the program can predict the key parameters such as peak pressure, temperature, and hydrogen production in containment well, and for most comparisons the relative errors can be maintained within 20%. Among them, the prediction uncertainty of hydrogen production is slightly larger. The analysis shows that the main sources of the error are the difference of time scale and the oxidation of cavity debris.

• 한국식생활문화학회지
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• 제24권6호
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• pp.721-727
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• 2009

In this study, the current status of the business foodservice industry, evaluation of leftover food and customer satisfaction with foodservice at direct operation and consignment foodservice businesses in Chungbuk were examined. This study has managerial implications in terms of improving the quality and effectiveness of the business operation of the foodservice industry. The sample size of this study included 800 customers who use foodservices provided by 11 selected businesses including 6 direct operation and 5 consignment foodservice businesses. From these 800 customers, a total of 692 were used (direct operation foodservice (n=361) and consignment foodservice (n=331) businesses). The results were as follows; First, as for the main reasons for using the employee restaurants in types of direct operation and consignment foodservice business, 'the close location' had the high percentage. Approximately 41% of respondents were not satisfied with the foodservice in the employee restaurants. Second, leftover food from consignment foodservices was higher than that for direct operation foodservices. Third, there were significant differences in customer satisfaction with five areas of foodservice between the two types of food service businesses: food, sanitation, feeding environment, mealing process and information and service. Customer satisfaction in the direct operation foodservice was higher than that of the consignment foodservice. In terms of the satisfaction level of foodservices, mealing process was the highest, followed by sanitation, food, and information and service in the direct operation and consignment foodservice businesses. Overall, satisfaction with the business foodservice was affected by the customers' satisfaction in five areas of foodservices (e.g., food, sanitation, feeding environment, mealing process, information and service). Especially, 'food' and 'information and service' were important areas for determining overall customer satisfaction with foodservice. In addition, the overall satisfaction was negatively correlated with the quantity of leftover food in the direct operation and consignment foodservice business.

• 지능정보연구
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• 제23권2호
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• pp.19-38
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• 2017

본 연구는 사용자 평점 이외에 사용자 간 직접 간접적 신뢰 및 불신 관계 네트워크의 분석 결과를 추가로 반영한 새로운 하이브리드 협업필터링(Collaborative filtering, CF) 추천방법을 제안한다. 구체적으로 사용자 간의 유사도를 계산할 때 사용자 평가점수의 유사성만을 고려하는 기존의 CF와 다르게, 사용자 신뢰 및 불신 관계 데이터의 사회연결망분석 결과를 추가적으로 고려하여 보다 정교하게 사용자 간의 유사도를 산출하였다. 이 때, 사용자 간의 유사도를 재조정하는 접근법으로 특정 이웃 사용자가 신뢰 및 불신 관계 네트워크에서 높은 신뢰(또는 불신)를 받을 때, 추천 대상이 되는 사용자와 해당 이웃 간의 유사도를 확대(강화) 또는 축소(약화)하는 방안을 제안하고, 더 나아가 최적의 유사도 확대 또는 축소의 정도를 결정하기 위해 유전자 알고리즘(genetic algorithm, GA)을 적용하였다. 본 연구에서는 제안 알고리즘의 성능을 검증하기 위해, 특정 상품에 대한 사용자의 평가점수와 신뢰 및 불신 관계를 나타낸 실제 데이터에 추천 알고리즘을 적용하였으며 그 결과, 기존의 CF와 비교했을 때 통계적으로 유의한 수준의 예측 정확도 개선이 이루어짐을 확인할 수 있었다. 또한 신뢰 관계 정보보다는 불신 관계 정보를 반영했을 때 예측 정확도가 더 향상되는 것으로 나타났는데, 이는 사회적인 관계를 추적하고 관리하는 측면에서 사용자 간의 불신 관계에 대해 좀 더 주목해야 할 필요가 있음을 시사한다.

• Archives of Pharmacal Research
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• 제9권3호
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• pp.153-156
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• 1986

The triterpenoid isolated from the seeds of Phytolacca plants was confirmed to be acetylaleuritolic acid rather than acetylepialeuritolic acid by direct comparison with synthetic compounds.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2004년도 추계학술대회 논문집
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• pp.304-305
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• 2004

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2009년도 추계학술대회 논문집
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• pp.671-672
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• 2009