• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.249-254
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• 2005

This paper presents the design of a novel small and wide band planar inverted F-antenna which simultaneously covers GSM900/GPS/DCS1800/DCS1900/DMB service. The proposed antenna consisting of a main patch with rectangular slit, strip 1 and strip 2, occupied the total volume of.$15\times36\times6mm^3$. A very wide impedance bandwidth characteristic was achieved by optimizing both the distance between the feed line and short strip and the length of rectangular slit on the main patch. The commercial electromagnetic software, CST Microwave Studio, is used to design the structure. The maximum gains at the frequencies of 900, 1575, 1800, 1900, and 2600 MHz were 2.07, 1.07, 1.69 and 0.55, -1.99 dBi, respectively. The overall shape of the radiation patterns is suitable for mobile communication application.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.82-89
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• 2006

It appears that it is possible for us to make a wireless communication of even home-network system within car by integrating with the Ubiquitous such as mobile phone, wireless Internet, GPS and DMB in the future. If the present wireless surroundings within the car are connected with very high-speed wireless network as measurement system for wireless communication surroundings within this car in the future, it will develop the complicated communication conditions such as safe checkup, communication between systems within car, and wireless communication for user entertainment unlike universal communication conditions. Accordingly, there is the necessity of the device that can measure the interference of electric wave, communication speed and communication quality by a kind of each car. This paper aims at making the real measurement device to raise the reliability of each Application for inquiring into the interference about each other in the frequency band used under Telematics surroundings.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.548-553
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• 2007

Digital convergence 및 ubiquitous 환경이 보편화되면서 computer system이 대부분의 전자 제품에 삽입되고 있다. 제품의 인터페이스는 더욱 복잡해지고 있으며, 사용 방법 또한 어려워지고 있는 상황이다. 이 중 Auto PC는 대표적인 예로, 차량 운전 환경에서 네비게이션, 음악, 동영상, DMB, PC 등의 기능을 지원하는 복합 제품이다. 이러한 제품의 사용자 인터페이스 설계를 위해서는 제품을 사용하면서 일어나는 행동들과 이들의 흐름을 이해할 수 있는 시나리오 설계에 관한 연구가 필수적이다. 인간공학 및 HCI 분야에서는 사용자 인터페이스를 설계하고 평가할 수 있는 방법론 및 도구들이 많이 소개되고 있다. 또한 이러한 방법 및 도구들을 상황에 맞게 선택하고 종합하고자 하는 연구 역시 다양하게 이루어지고 있다. 본 연구에서는 인간 중심 설계(human centered design) 방법론 중 대표적인 시나리오 기반 설계(SBD: Scenario-Based Design)과 직무분석(Task Analysis)을 이용하여 Auto PC의 인터페이스 설계에 적용해보았다. 시나리오 기반 설계와 직무분석 두 방법론을 통합할 수 있는 프로세스를 적용하였고, 그 결과 각 방법론의 단점을 서로 보완할 수 있었다. 추후 prototype을 완성하고 사용성 평가 및 만족도 조사를 통하여 설계된 인터페이스를 검증하는 연구가 진행될 예정이다.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.131-135
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• 2005

Nowadays, the demand for the wireless technology has gradually increased to support the services of high speed wired internet and also the interest of a mobile terminal convergence has increased. In the next generation, the mobile terminal could merge with the celluar phone, wireless LAN, portable internet, digital multimedia brodcasting, mobile game and sensor(smart-tag and biometrics) through the unified single user interface. Moreover, the system is supported to multi-mode at difference networks, which have variable functions and high performance for available service. Inthis paper, we investigate the minimum requirements and the core technologies of the next generation mobile terminals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.745-753
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• 2011

In this paper, the planar monopole antenna for multi-band service is proposed. The proposed antenna, which is a rectangular patch antenna with a U-shaped slit based on a monopole antenna for wide bandwidth characteristic, is designed and analyzed. The antenna size has been miniaturized by using the U-shaped slit. The frequency characteristics are modified and optimized by varying specific parameters. To obtain desired frequency bands, the U-shaped slit and patch lines have been applied. Whole antenna dimensions including the ground plane are $35{\times}50{\times}1\;mm^3$, and the antenna part size is $35{\times}27\;mm^2$. It is fabricated on the FR-4 substrate(${\epsilon}_r=4.4$) using a microstrip line of $50{\Omega}$ for impedance matching. For the measured results, the impedance bandwidth below a VSWR of 2 is 790~916 MHz, 1.74~2.14 GHz, and 2.36~3.13 GHz. The fabricated antenna is satisfied with the aimed impedance bandwidth in GSM/DCS/US-PCS/UMTS/Bluetooth/S-DMB applications.

• Journal of Intelligence and Information Systems
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• v.16 no.4
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• pp.147-157
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• 2010

With the immergence of the iPhone, the interest in Smartphones is getting higher as services can be provided directly between service providers and consumers without the network operators. As the number of international tourists increase, individual tourists are also increasing. According to the WTO's (World Tourism Organization) prediction, the number of international tourists will be 1.56 billion in 2020,and the average growth rate will be 4.1% a year. Chinese tourists, in particular, are increasing rapidly and about 100 million will travel the world in 2020. In 2009, about 7.8 million foreign tourists visited Korea and the Ministry of Culture, Sports and Tourism is trying to attract 12 million foreign tourists in 2014. A research institute carried out a survey targeting foreign tourists and the survey results showed that they felt uncomfortable with communication (about 55.8%) and directional signs (about 21.4%) when they traveled in Korea. To solve this inconvenience for foreign tourists, multilingual servicesfor traffic signs, tour information, shopping information and so forth should be enhanced. The appearance of the Smartphone comes just in time to provide a new service to address these inconveniences. Smartphones are especially useful because every Smartphone has GPS (Global Positioning System) that can provide users' location to the system, making it possible to provide location-based services. For improvement of tourists' convenience, Seoul Metropolitan Government hasinitiated the u-tour service using Kiosks and Smartphones, and several Province Governments have started the u-tourpia project using RFID (Radio Frequency IDentification) and an exclusive device. Even though the u-tour or u-tourpia service used the Smartphone and RFID, the tourist should know the location of the Kiosks and have previous information. So, this service did not give the solution yet. In this paper, I developed a new convenient service which can provide location based information for the individual tourists using GPS, WiFi, and 3G. The service was tested at Insa-dong in Seoul, and the service can provide tour information around the tourist using a push service without user selection. This self-tour service is designed for providing a travel guide service for foreign travelers from the airport to their destination and information about tourist attractions. The system reduced information traffic by constraining receipt of information to tourist themes and locations within a 20m or 40m radius of the device. In this case, service providers can provide targeted, just-in-time services to special customers by sending desired information. For evaluating the implemented system, the contents of 40 gift shops and traditional restaurants in Insa-dong are stored in the CMS (Content Management System). The service program shows a map displaying the current location of the tourist and displays a circle which shows the range to get the tourist information. If there is information for the tourist within range, the information viewer is activated. If there is only a single resultto display, the information viewer pops up directly, and if there are several results, the viewer shows a list of the contents and the user can choose content manually. As aresult, the proposed system can provide location-based tourist information to tourists without previous knowledge of the area. Currently, the GPS has a margin of error (about 10~20m) and this leads the location and information errors. However, because our Government is planning to provide DGPS (Differential GPS) information by DMB (Digital Multimedia Broadcasting) this error will be reduced to within 1m.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.23-31
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• 2007

In this paper, UWB system did research about effect that interference effect with neighborhood single equipment or group equipment gets in broadcasting communication service. For this, 2.6425GHz SDMB(Satellite Digital Multimedia Broadcasting) that a special of electric wave interference is near frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and degree of 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect that get in service analyzed comparison and, modulation of broadcasting relay net and interference measurement equipment used Impulse and OFDM methods. Impulse method was $BER\;=\;1{\times}\;10^{-4}$ that broadcasting signal receiption is possible at 1.4m point because interference effect happens from 2m point in SDMB system, and it was $BER\;=\;1{\times}\;10^{-4}$ that OFDM method receives interference effect from 0.8m point and broadcasting signal receiption is possible at 0.5m point. Also, about Gap-Filler center frequency, In case of space interval more than 0.01m, there was no interference effect. Therefore, for the electric wave of UWB system that is small output applies to system without interference effect in broadcasting communication service, confirmed that UWB system of OFDM method is less interference effect than UWB system of Impulse method.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.175-178
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• 2006

1990 년대부터 본격적으로 시작된 국내 휴대폰의 역사는 불과 10 년 사이에 전체 인구 중 3600 만명 이상의 가입자가 휴대폰을 사용하고 있는 모바일 강국으로 발전하였다. 국내 이동통신사들의 다양한 서비스 전략과 단말 제조사들의 다양한 기술의 발전으로 휴대폰은 단순한 전화기능만을 담당하는 커뮤니케이션 디바이스(Communication Device)에서 다양한 VOD, AOD 서비스들의 도입으로 엔터테인먼트 디바이스(Entertainment Device)로 발전했고, DMB, TV, MP3, 카메라 등 다양한 디바이스들이 결합된 컨버전스 기능성 기기(Functional Device)로 발전해 가고 있다. 이런 과정에서 사용자들은 휴대폰에서 다양한 경험을 하게 된다. 본 연구는 다양한 매체와 디바이스가 결합 된 모바일 환경 속에서 이동통신사와 제조사의 관점에서 분석한 자료를 바탕으로 하나의 통합된 경험을 사용자들에게 제공할 수 있는 방법을 고찰해 보고자 한다. 휴대폰을 만드는 제조업체가 수행하는 경험 디자인은 이동통신사에 상관없이, 자사의 경험 통일성(identity)을 강조하게 되고, 이동통신사는 제조업체와 상관없이 자사의 경험 통일성을 강조하게 된다. 통일성 뿐만 아니라 기능이나 직무(task)의 중요성도 다르기 때문에 경험 디자인을 위한 우선순위도 다르게 된다. 이것의 결과는 모두 사용자가 떠 앉게 된다. 즉 사용자의 경험이 복잡해지게 되고 이것은 장기적으로 제조업체 및 이동통신사 모두에게 불이익을 주게 된다. 본 논문에서는 제조사와 이통사를 위한 사용자 경험 모형을 세웠고, 각 요소별로 접근 방법의 차이에 대해 논의를 하였다. 사용자가 휴대폰 경험에서 혼돈을 적게 하기 위해서는 제조사와 이통사의 인터랙션은 서로 일관성이 있어야 하고, 스타일 부문에서는 서로간의 입장차이가 좁히기 쉽지 않으므로 둘 다 사용자의 선택의 폭을 넓혀주는 방향으로 진행을 한다. 기획단계에서 부터 협력을 함으로써 양사의 갭을 줄일 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.66-72
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• 2011

In Japan, the specification for digital terrestrial television broadcasting systems has been approved for employing a transmission scheme for ISDB-T, which can accommodate HDTV service and portable mobile reception by adapting segmentation of frequency. In this paper, we have developed 3.5 inch mobile TV according to One-Seg system and presented the results of our development. In addition, we introduce two diversity schemes to compensate the defect that signal is interrupted when the portable TV is moving fast. In order to achieve a reliable communication in One-Seg system, we introduce STD(space time diversity) which uses more than 2 antennas at TX and cooperative reception diversity which utilizes signal-exchanging between different mobile terminals. And, its performance enhancements to reception reliability of previous system are evaluated by computer simulations.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.137-148
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• 2007

Due to the advance of technology, the technology of various media is rapidly converged into digital technology. However, the conversion into digital radio is not achieved in korea yet. This paper is to suggest the best method of digital conversion of radio in korea by examining some conversion examples in foreign countries. In addition, the survey results on radio audience attitude is analysed by 2,000 audience samples in Korea based on the literature analysis. Radio is the unique media which have the strengths such as mobility, individuality, presence, broad coverage and instant. Most of all, radio cannot help keeping continuously the public broadcasting service in the future. So, the conversion into digital radio is crucial to sustain the competitiveness in digital media environment. This paper suggested that the digital conversion of radio broadcasting needs DRM transmission and should pursuit the policy which is distinguished between a AM and a standard FM, and between domestic broadcast and an international broadcast. Additionally, this paper proposed that we need to develop the multiple device for receiving of signal and the setting of standard technology.