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BCTZ첨가가 NKLN-AS계 압전세라믹스의 미세구조와 압전/유전특성 및 상전이현상에 미치는 효과
이웅재,어순철,이영근,윤만순,Lee, Woong-Jae,Ur, Soon-Chul,Lee, Young-Geun,Yoon, Man-Soon 한국재료학회 2012 한국재료학회지 Vol.22 No.1
Presently, the most promising family of lead-free piezoelectric ceramics is based on $K_{0.5}Na_{0.5}NbO_3$(KNN). Lithium, silver and antimony co-doped KNN ceramics show high piezoelectric properties at room temperature, but often suffer from abnormal grain growth. In the present work, the $(Ba_{0.85}Ca_{0.15})(Ti_{0.88}Zr_{0.12})O_3$ component, which has relaxor ferroelectric characteristics, was doped to suppress the abnormal grain growth. To investigate this effect, Lead-Free $0.95(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}NbO_3-(0.05-x)AgSbO_3-x(Ba_{0.85}Ca_{0.15})(Ti_{0.88}Zr_{0.12})O_3$[KNLN-AS-xBCTZ] piezoelectric ceramics were synthesized by ball mill and nanosized-milling processes in lead-Free $0.95(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}NbO_3-(0.05-x)AgSbO_3$ in order to suppress the abnormal grain growth. The nanosized milling process of calcined powders enhanced the sintering density. The phase structure, microstructure, and ferroelectric and piezoelectric properties of the KNLN-AS ceramics were systematically investigated. XRD patterns for the doped and undoped samples showed perovskite phase while tetragonality was increased with increasing BCZT content, which increase was closely related to the decrease of TO-T. Dense and uniform microstructures were observed for all of the doped BCZT ceramics. After the addition of BCTZ, the tetragonal-cubic and orthorhombic-tetragonal phase transitions shifted to lower temperatures compared to those for the pure KNNL-AS. A coexistence of the orthorhombic and tetragonal phases was hence formed in the ceramics with x = 0.02 mol at room temperature, leading to a significant enhancement of the piezoelectric properties. For the composition with x = 0.02 mol, the piezoelectric properties showed optimum values of: $d_{33}$ = 185 pC/N, $k_P$ = 41%, $T_C=325^{\circ}C$, $T_{O-T}=-4^{\circ}C$.
노인전문병원의 의료서비스 품질이 고객만족과 재이용의도에 미치는 영향
이웅재 ( Woong-jae Lee ),최호규 ( Ho-gyu Choi ) KNU기업경영연구소 2010 기업경영리뷰 Vol.1 No.2
The Purpose of this study is to explain effect of medical service quality on the customer satisfaction and intention to revisit of geriatric hospital. Medical service factors of geriatric hospital were classified into nine factors; tangibles, reliability, responsiveness, assurance, empathy, spy, cone, access, and amenity by review the literature. Two hypotheses are offered with the previous researches, and the first was described by nine sub hypotheses. To verify these hypotheses, 198 valid sample data were collected and the data were examined using statistical analyses including frequency analysis, exploratory factor analysis, reliability analysis, simple linear regression, and multi-linear regression analysis. According to the results of simple linear regression analyses, nine factors of medical service quality have a significant positive effect to customer satisfaction individually. In addition, customer satisfaction have a significant positive effect to intention to revisit. Especially according to the result of multi linear regression analyses, just three factors of medical service quality: tangibles, reliability, assurance have a significant positive effect to customer satisfaction.
李雄宰(Lee Woong-jae) 중앙어문학회 2003 語文論集 Vol.31 No.-
This thesis contains the study of ‘seasonal customs poetry’ which has originated with the dog. The rather light methodology in this thesis was congenial to the nature of the object (dog) itself, and it gave this study a proper consequence, And it is summarized as follows. 1. Seasonal customs poetry according to an almanac has probably been observed since ‘the era of the Three Kingdoms’ in this country. 2. Remarkably imperfect records of seasonal customs poetry in our compendium of seasonal words were brought about by frequent invasions of foreign countries in history. 3. A term, ‘Thie’[?i] - the oriental zodiac sign under which one was born (in what we call the Year of the Dog or Horse) involves the meaning of a wagon wheel. And metempsychosis (doctrine of transmigration of souls) like that has created by the common people. 4. Both of affirmative and negative sides a dog has are faithfulness (or nature of gratitude) and polyphagia (or wildness), respectively. Manners and customs of the people, by a long-established tradition, take root into folkways. Thus by our sorting out good folkways, we have to make those develope into more valuable seasonal customs poetry and public morals in the future.
기반 기술 : 무선 네트워크 자원 효율 향상을 위한 비디오 픽처 기반 오류 제어 기법
손예진 ( Ye Jin Sohn ),이웅재 ( Woong Jae Lee ),백종호 ( Jong Ho Paik ) 한국항행학회 2014 韓國航行學會論文誌 Vol.18 No.1
통신 기술의 발달과 고성능 무선 단말기들의 출시로 무선 환경에서 비디오 스트리밍 서비스 사용자 수는 빠른 속도로 증가하고 있다. 제한된 네트워크 환경에서 많은 사용자에게 UHD급 화질의 비디오 스트리밍 서비스를 제공하기 위해서는 오류 제어 기술은 필수적이다. 이전에 지연에 민감한 비디오 서비스의 오류 제어를 위해서 packet-level FEC(Forward Error Control)기법이 사용되었지만, 이 기술은 중복 데이터에 의한 네트워크 자원 점유가 크다는 단점이 존재한다. 따라서 본 논문에서는 제한된 대역폭을 가진 네트워크 환경에서 기존 FEC 기법들이 제공하는 비디오 서비스 품질은 유지하면서 FEC 데이터에 의한 네트워크 점유를 줄이는 packet-level FEC 알고리즘을 제안한다. 제안 알고리즘은 비디오 압축 기술의 전송 특성을 이용하여 FEC 중복비율을 조정하며, 실험 결과 이전 기법과 비교하여 약 33% 정도의 전송량을 줄임으로써 네트워크 자원 효율을 향상시킬 수 있다. Due to the development of the communication technology and the high-performance mobile device, the number of video streaming service user has been increasing. Video streaming services in the restricted network environments need error control to support users for the Ultra High Definition(UHD) video delivery. Packet-level FEC method was used to control the error for delay-sensitive video service, but it has a defect in huge occupation of network resources by redundant packets. In this paper, we proposed a packet-level FEC algorithm which maintains the video quality by previous FEC methods and also reduces the occupation of network resource in the restricted network environments. The proposed algorithm controls the redundant rate with using the delivery characteristic of the video coding technology, and improves the efficiency of network resources by reducing the traffic by around 33% in comparison with the previous FEC methods.
노안젤라송이 ( Angela Song Ie Noh ),이웅재 ( Woong Jae Lee ) 한국인터넷정보학회 2010 인터넷정보학회논문지 Vol.11 No.1
본 논문은 실내 위치 인식을 위하여 ZigBee 이동 장치의 위치를 측정하였으며 Bayesian Markov 위치 추론 기법을 적용하였다. 정확도 분석을 위해 기존의 지도 기반의 위치 인식 기법과 비교하였는데 이 기법은 이미 지정된 위치에서의 RSSI 데이터를 데이터베이스화하여 참조하도록 하는 반면 Bayesian Markov 추론 방법은 시간, 방향, 거리의 변화에 영향을 받았다. 이 두 가지 방법에 따른 측정은 지그비 모듈을 사용하여 RSSI를 측정한 결과를 토대로 이루어졌으며 그 결과 실내에서의 RSSI와 거리와의 관계로 접근하는 것이 바람직하며 Bayesian Markov에 의한 분석결과 기존의 지도 기반 위치 인식 기법에 비하여 높은 정확도를 보여주었다. 결과적으로 기존의 지도 기반 위치 인식 기법은 사전에 환경 요인에 대한 설정을 해주어야 하고, 보다 낮은 정확도를 가지고 있으므로 환경 변화가 잦은 실내에서는 부적합하다고 생각된다. This paper applies Bayesian Markov inferred localization techniques for determining ZigBee mobile device`s position. To evaluate its accuracy, we compare it with conventional technique, map-based localization. While the map-based localization technique referring to database of predefined locations and their RSSI data, the Bayesian Markov inferred localization is influenced by changes of time, direction and distance. All determinations are drawn from the estimation of Received Signal Strength (RSS) using ZigBee modules. Our results show the relationship between RSSI and distance in indoor ZigBee environment and higher localization accuracy of Bayesian Markov localization technique. We conclude that map-based localization is not suitable for flexible changes in indoors because of its predefined condition setup and lower accuracy comparing to distance-based Markov Chain inference localization system.