• Title/Summary/Keyword: Hall Device

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Growth and characterization of molecular beam epitaxy grown GaN thin films using single source precursor with ammonia

  • Chandrasekar, P.V.;Lim, Hyun-Chul;Chang, Dong-Mi;Ahn, Se-Yong;Kim, Chang-Gyoun;Kim, Do-Jin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.174-174
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    • 2010
  • Gallium Nitride(GaN) attracts great attention due to their wide band gap energy (3.4eV), high thermal stability to the solid state lighting devices like LED, Laser diode, UV photo detector, spintronic devices, solar cells, sensors etc. Recently, researchers are interested in synthesis of polycrystalline and amorphous GaN which has also attracted towards optoelectronic device applications significantly. One of the alternatives to deposit GaN at low temperature is to use Single Source Molecular Percursor (SSP) which provides preformed Ga-N bonding. Moreover, our group succeeds in hybridization of SSP synthesized GaN with Single wall carbon nanotube which could be applicable in field emitting devices, hybrid LEDs and sensors. In this work, the GaN thin films were deposited on c-axis oriented sapphire substrate by MBE (Molecular Beam Epitaxy) using novel single source precursor of dimethyl gallium azido-tert-butylamine($Me_2Ga(N_3)NH_2C(CH_3)_3$) with additional source of ammonia. The surface morphology, structural and optical properties of GaN thin films were analyzed for the deposition in the temperature range of $600^{\circ}C$ to $750^{\circ}C$. Electrical properties of deposited thin films were carried out by four point probe technique and home made Hall effect measurement. The effect of ammonia on the crystallinity, microstructure and optical properties of as-deposited thin films are discussed briefly. The crystalline quality of GaN thin film was improved with substrate temperature as indicated by XRD rocking curve measurement. Photoluminescence measurement shows broad emission around 350nm-650nm which could be related to impurities or defects.

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The Discipline of the Dom-ino Frame and the Regulating Line - A Study of Le Corbusier's Villa La Roche-Jeanneret and Villa Stein-de Monzie - (르 꼬르뷔제 건축에서 돔-이노 프레임과 규준선의 기율 - 라 로쉬-잔느레 주택과 가르쉬 주택을 중심으로 -)

  • Pai, Hyung-Min;Hyun, Myung-Seok
    • Journal of architectural history
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    • v.12 no.1 s.33
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    • pp.25-41
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    • 2003
  • This paper is a study of Le Corbusier's trace regulateur of the 1920s, particularly its role in the design of the Villas La Roche-Jeanneret and Stein-de Monzie. It proceeds on the basis of the following three themes: first, the relation between the regulating line and the dom-ino frame; second, its status as a proportional device based not on a module system but one that defines relations; third, its function as an essential practical device in the design process. In the Villa La Roche-Jeanneret, the embedded horizontal planes of the dom-ino frame were constant, but the vortical lines of the columns were altered according to the changes in plan. Initially, a left-hand bay window formed a symmetry with the right-hand bay window, the only constant in the design process. With subsequent changes, mullion sections of the horizontal window and roof elements came to provide the reference points for the regulating line. Eventually, a regulating line different from the one that controlled the bay window and the elongated volume came to control the entrance hall of Villa La Roche, resulting in three different kinds of regulating lines in the final version. In contrast to the Villa La Roche-Jeanneret, a singular and consistent regulation line was anticipated in the earliest design stages of the Villa Stein-de Monzie. The repetition of its A:B grid and the standard $2.5m{\times}1.0m$ sliding window determined the proportions of both its plan and elevation, and thus the regulating line became 'automatic,' losing its viability as a practical tool. Though the regulating titles of the La Roche-Jeanneret look as if they were an afterthought, drawn after the design was complete, they were most active, requiring tenacity and discipline in their application. On the other hand, the seemingly 'redundant' regulating line of the Villa Stein-de Monzie gains its raison d'etre from the dom-ino frame. Its cantilevers and uninterrupted horizontal window could be used in decisive fashion because of the guarantee that the correct proportion would always be maintained. Thus we discover that Le Corbusier's discipline of the 1920s had a certain spectrum of flexibility. His 'parti' ranged from the extremely loose and malleable grid of the Villa La Roche-Jeanneret to the fixed grid of the Villa Stein-de Monzie. In different ways, these projects retain the tension between the dom-ino frame and the regulating line. For Le Corbusier, as much as the grid was an object with fixed attributes, it was also an active medium manipulated by the will of the architect.

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All Solution processed BiVO4/WO3/SnO2 Heterojunction Photoanode for Enhanced Photoelectrochemical Water Splitting

  • Baek, Ji Hyun;Lee, Dong Geon;Jin, Young Un;Han, Man Hyung;Kim, Won Bin;Cho, In Sun;Jung, Hyun Suk
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.417-417
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    • 2016
  • Global environmental deterioration has become more serious year by year and thus scientific interests in the renewable energy as environmental technology and replacement of fossil fuels have grown exponentially. Photoelectrochemical (PEC) cell consisting of semiconductor photoelectrodes that can harvest light and use this energy directly to split water, also known as photoelectrolysis or solar water splitting, is a promising renewable energy technology to produce hydrogen for uses in the future hydrogen economy. A major advantage of PEC systems is that they involve relatively simple processes steps as compared to many other H2 production systems. Until now, a number of materials including TiO2, WO3, Fe2O3, and BiVO4 were exploited as the photoelectrode. However, the PEC performance of these single absorber materials is limited due to their large charge recombinations in bulk, interface and surface, leading low charge separation/transport efficiencies. Recently, coupling of two materials, e.g., BiVO4/WO3, Fe2O3/WO3 and CuWO4/WO3, to form a type II heterojunction has been demonstrated to be a viable means to improve the PEC performance by enhancing the charge separation and transport efficiencies. In this study, we have prepared a triple-layer heterojunction BiVO4/WO3/SnO2 photoelectrode that shows a comparable PEC performance with previously reported best-performing nanostructured BiVO4/WO3 heterojunction photoelectrode via a facile solution method. Interestingly, we found that the incorporation of SnO2 nanoparticles layer in between WO3 and FTO largely promotes electron transport and thus minimizes interfacial recombination. The impact of the SnO2 interfacial layer was investigated in detail by TEM, hall measurement and electrochemical impedance spectroscopy (EIS) techniques. In addition, our planar-structured triple-layer photoelectrode shows a relatively high transmittance due to its low thickness (~300 nm), which benefits to couple with a solar cell to form a tandem PEC device. The overall PEC performance, especially the photocurrent onset potential (Vonset), were further improved by a reactive-ion etching (RIE) surface etching and electrocatalyst (CoOx) deposition.

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The Study on the Interface Design for supporting the Exhibition Viewing (전시환경을 위한 전시관람 지원 인터페이스 디자인에 관한 연구)

  • Choi, Ji-Eun;Jung, Ji-Hong
    • Journal of the HCI Society of Korea
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    • v.1 no.1
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    • pp.81-88
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    • 2006
  • With the introduction of the digital technology in the exhibition environment, the information of the exhibit has come to be transmitted through diverse media. The visitors desire has been increased from the simple viewing of the exhibition to the active participation in the exhibition viewing and the utilization of the exhibit information. Subsequently, the study on the service to effectively support the viewing experience and provide the information by utilizing the internet and mobile device for visitors in movement has become important in terms of the exhibition environment. Accordingly, in this study, the current condition in studying the service supporting the exhibition environment and the exhibition viewing, which are being changed into a digital network environment, was examined through the literature and case studies. In order to find out the viewing situation and viewing type of visitors, the visitors behaviors of viewing the exhibition were observed. By analyzing the contents observed, the viewing type and keyword were drawn in accordance with the visitors behaviors of viewing. On the basis of this, visitors needs and problems occurring in case of the exhibition viewing were found out via in-depth interview. The service factors of supporting the exhibition viewing were proposed on the basis of the factors by which visitors needs and problems could be solved via interface in the circumstance when visitors would move round the exhibition hall and view the exhibition. In terms of the service factors, the method to resolve was presented on the basis of the relationship between the exhibit and the space in case of selecting and viewing the exhibit. This was applied into the mobile PDA with the example of the exhibition environment in the national museum. Through the scenario of using, the usefulness of the service proposed and the relevant possibility of utilization were reviewed.

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A Diachronic Study on the Transition Process of the Royal Library during the Gojong Period (고종대 왕실도서관의 변천 과정에 관한 통시적 고찰)

  • Song, Sung-Seob
    • Journal of the Korean Society for Library and Information Science
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    • v.56 no.3
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    • pp.213-239
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    • 2022
  • This study attempted to organize the transition process of Royal Library (Gyujanggak) in chronological order, analyze the flow and find diachronic meaning during Gojong period, the most confused time at home and abroad prior to modernization. For this, first, the total status quo of King Gojong's library and book storage which played role of Royal Library and a personal library in Gojong period was investigated. Second, based on the current status of the investigation, the transition process from the Royal library in the early days of King Gojong to the Imperial library during the Korean Empire and its meaning were considered with the Annals of the Joseon Dynasty, Seungjeongwon diary, various catalogs and historical records. Third, the changes of space-time and aspect of Royal library through the palace of Gyeongbokgung, Changdeokgung, and Gyeongungung were examined to draw a sociopolitical meaning by schematizing each palace. As a result, first, King Gojong conjugated Kyujanggak as a device to strengthen the royal authority and accommodate Western culture in the process of modernization. Second, the crucial spaces containing the political orientation of King Gojong, such as the present king's portrait storage place, library(book storage), and office, formed a separate hall across Gyeongbokgung, Changdeokgung, Gyeongungung, and gradually changed into a Western architectural style.

System Development for Measuring Group Engagement in the Art Center (공연장에서 다중 몰입도 측정을 위한 시스템 개발)

  • Ryu, Joon Mo;Choi, Il Young;Choi, Lee Kwon;Kim, Jae Kyeong
    • Journal of Intelligence and Information Systems
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    • v.20 no.3
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    • pp.45-58
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    • 2014
  • The Korean Culture Contents spread out to Worldwide, because the Korean wave is sweeping in the world. The contents stand in the middle of the Korean wave that we are used it. Each country is ongoing to keep their Culture industry improve the national brand and High added value. Performing contents is important factor of arousal in the enterprise industry. To improve high arousal confidence of product and positive attitude by populace is one of important factor by advertiser. Culture contents is the same situation. If culture contents have trusted by everyone, they will give information their around to spread word-of-mouth. So, many researcher study to measure for person's arousal analysis by statistical survey, physiological response, body movement and facial expression. First, Statistical survey has a problem that it is not possible to measure each person's arousal real time and we cannot get good survey result after they watched contents. Second, physiological response should be checked with surround because experimenter sets sensors up their chair or space by each of them. Additionally it is difficult to handle provided amount of information with real time from their sensor. Third, body movement is easy to get their movement from camera but it difficult to set up experimental condition, to measure their body language and to get the meaning. Lastly, many researcher study facial expression. They measures facial expression, eye tracking and face posed. Most of previous studies about arousal and interest are mostly limited to reaction of just one person and they have problems with application multi audiences. They have a particular method, for example they need room light surround, but set limits only one person and special environment condition in the laboratory. Also, we need to measure arousal in the contents, but is difficult to define also it is not easy to collect reaction by audiences immediately. Many audience in the theater watch performance. We suggest the system to measure multi-audience's reaction with real-time during performance. We use difference image analysis method for multi-audience but it weaks a dark field. To overcome dark environment during recoding IR camera can get the photo from dark area. In addition we present Multi-Audience Engagement Index (MAEI) to calculate algorithm which sources from sound, audience' movement and eye tracking value. Algorithm calculates audience arousal from the mobile survey, sound value, audience' reaction and audience eye's tracking. It improves accuracy of Multi-Audience Engagement Index, we compare Multi-Audience Engagement Index with mobile survey. And then it send the result to reporting system and proposal an interested persons. Mobile surveys are easy, fast, and visitors' discomfort can be minimized. Also additional information can be provided mobile advantage. Mobile application to communicate with the database, real-time information on visitors' attitudes focused on the content stored. Database can provide different survey every time based on provided information. The example shown in the survey are as follows: Impressive scene, Satisfied, Touched, Interested, Didn't pay attention and so on. The suggested system is combine as 3 parts. The system consist of three parts, External Device, Server and Internal Device. External Device can record multi-Audience in the dark field with IR camera and sound signal. Also we use survey with mobile application and send the data to ERD Server DB. The Server part's contain contents' data, such as each scene's weights value, group audience weights index, camera control program, algorithm and calculate Multi-Audience Engagement Index. Internal Device presents Multi-Audience Engagement Index with Web UI, print and display field monitor. Our system is test-operated by the Mogencelab in the DMC display exhibition hall which is located in the Sangam Dong, Mapo Gu, Seoul. We have still gotten from visitor daily. If we find this system audience arousal factor with this will be very useful to create contents.