• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.47-54
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• 1990

In this paper, we design the 4-bit phase shifter which have $22.5^{\circ},45^{\circ},90^{\circ}$ and $180^{\circ}$ phase shift by applying the loaded line and switched network phase shifter. Its phase shift is variable with changing of the stub and passive device parameters. The experiments show the 6.5 dB average insertion loss and $10^{\circ}$ average phase error at center frequency, 6GHz. The results of experiment agree well with the theories except $180^{\circ}$ phase shifter.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.119-128
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• 2006

The web based coursewares that are operating currently can not support individual studying capabilities appropriately. To solve this problem, this paper can provide individual students with a tool that makes contents of lessons to be organized according to study subjects, study objective, and study scope by students. And it is designed for study contents to be condensed into a courseware and be operated in a courseware. Also this method can continuously stimulate a study motivation by providing selective control system without a predefined linear study plan. And it also can have the contents of study coincide with their interests and needs. Therefore this method maximizes accomplishments for the study contents and satisfaction for way of study.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.141-145
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• 2017

This paper presents a method to improve Li-ion battery charging speed for portable electronic devices maintaining stable operating temperature. The proposed method uses multiple chargers which consist of a master module and slave modules designed with single wire communication signal for parallel current path in order to simplify the additional hardware needs. A single wire communication signal control between a master module and slave modules makes the number of pins of parts lowered and the required area small, furthermore leading to lower cost. Therefore the proposed charging method can be practically used for implementing battery charging modules requiring high speed Li-ion battery charging.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.350-353
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• 2004

The integral reactor is tripped by the boron injection to the reactor when the CEA(Control element assembly) is not available due to its malfunction. In general, the borated water is made by dissolving the boron powder in the water and is stored in a tank. and then injected. But, this method is disadvantageous from the view point of construction cost, operation and maintenance because it has many components and is complicated. In this study, the boron powder direct vessel injection method is adopted to improve the system. Injecting the boron powder directly to the vessel and decreasing of number of components, the system configuration, operation and maintenance is simplified and the construction cost is reduced.

• The Journal of the Korea Contents Association
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• v.11 no.6
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• pp.385-396
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• 2011

Internet web pages can be classified by three major types such as texts only, images with texts and videos with texts. The purpose of this paper is to analyze how customers recognize and respond perspective of perceived risk and media richness with regard to design patterns of internet web pages. Additionally, we will examine the extent to which aforementioned factors affect customer satisfaction. Analyses with perceived risks revealed that customers feel less personal risks including performance, psychology and time/convenience when used web pages of text-images and text-videos, compared to text only based web pages. However, customers feel that web pages consisting of image-text or video-text have higher points in terms of symbolism and social presence in media richness, compared to text only based web pages. Finally, we showed that personal risk and text-based Web page negatively affect but symbolism and social presence positively impact on customer satisfaction. Therefore, this study suggests a clue that why video-based Web content did not grow different from many people's expectation.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.417-423
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• 2020

The purpose of this study is to study the elements that make up the interface design of the applicatio, focusing on Android's Google Material Design Guidelines. and propose a way to produce the UI design guide by categorizing it according to form and combination methods. The components provided by the Materials Design Guidelines were disassembled form and attributes, types, and the characteristics. The components of UI design include surfaces, letters, icons, and media, which enable the creation of UI style guides, and the components for the purpose of exploring and communicating information, with different components and rules of use used for the purpose. Based on these results, I would like to propose design criteria for the interface of mobile applications and how to utilize it effectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.15-26
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• 2001

Visual cryptography is a simple method in which secret information can be directly decoded in human visual system without any cryptographic computations. When the secret image is scattered to n random shares(slides), this scheme has some week point such as pixel expansion and contrast degradation. Therefore, it is necessary to reduce the pixel expansion and improve the contrast in recovered image. In this paper, we propose a new construction method for (k, n) visual cryptography using the cumulative matrix. In case k is odd, we can construct the cumulative matrix perfectly. For even k, the contrast of special pair in decoded image can be achieved best by permitting multiple contract. The proposed method is more simple than that of S. Droste\`s in construction and the average contrast of decoded image is improved for the most part. Also, we show that the basis matrices depending on the cumulative matrix are able to be applied for the general access structure.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.425-428
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• 2000

본 논문은 B2C기반의 전자상거래 쇼핑몰에서 후불방식의 전화번호에 상품 구매 대금을 지불할 수 있도록 하는 전화요금결제 시스템의 구성 및 기능에 관한 것이다. 전화요금결제 게이트웨이 (Telephone Payment Gateway ： TPG)는 기존 웹/머쳔트 서버 (Web/Merchant Server), 고객관리 시스템 및 요금관리 시스템과 TCP/IP를 기반으로 하여 연동되어, 쇼핑몰 가입자에게 신용카드, 전자화폐 wallet, on-line 입금 등의 지불 방식과는 다른 지불 방식을 제공함으로써, 지불 방식의 다양화를 도모할 수 있고, 인터넷 사용자 대부분이 가지고 있는 PSTN/ISDN 번호를 가지고 쇼핑몰 상품 대금을 지불할 수 있어서, 전 국민을 가입자로 확보할 수 있는 서비스이다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.235-236
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• 2016

본 연구에서는 고 성능 마이크로프로세서를 이용한 공기조형물의 관절 구동과 센서의 환경 인식에 능동적으로 대처할 수 있는 시스템을 연구하였다. 객체기반의 공기조형물용 모션제어 시스템은 단일 제어기로의 역할보다 시스템 구성요소로서의 역할이 매우 중요해지므로 시스템 전체의 제어기로 확장시켜 사용하는 방향으로 전환되어야 한다. 본 연구에서는 시스템의 구동과 환경에 능동적으로 대처할 수 있는 객체기반 공기조형물을 연구하였다. 모터제어 방법에 있어 CAN(Controller Area Network) 네트워크를 방식을 통하여 제어를 수행하는 분산제어방식으로 수행하였다. CAN방식은 모션제어 시스템에 도입하여 주 제어기가 하위 제어기에 네트워크를 통하여 명령을 내리며 하위제어기는 주어진 위치 및 속도명령에 대하여 분산적으로 제어를 수행하였다. 따라서 CAN방식을 사용하여 각 제어기의 독립성과 처리속도를 증대시키고 공기조형물의 기능별 확장이 용이하도록 구성하였다. 제어기의 환경은 시스템을 총체적으로 조화롭게 제어할 수 있는 시스템으로의 역할이 중요시되어 이에 맞도록 설계방안을 연구하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.268-270
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• 2001

현재 ad hoc의 연구 방향은 무천 기반의 패킷 라우팅에 관련된 것이 대부뿐 이러 네트워크 토폴로지 생성에 대한 연구는 거의 진행된 것이 없다. 현재 대부분의 ad hoc 네트워크는 대표적인 싱글 채널 방식인 broadcast 기반의 무선 미디어 방식을 물리적 계층을 사용하며, 이를 기반으로 이동 노드의 무선 범위 제한을 극복하기 위한 형태로 네트워크 토폴로지를 형성한다. 블루투스(B1uetooth)는 frequency hopping(FH) 방식을 사용하므로 연결 설정 과정에서 동기화 과정이 반드시 요구되며, ad hoc 네트워크을 형성을 위해 다중 채널을 사용한다. 따라서 블루투스와 같이 다중 채널을 물리적 계층으로 사용하는 네트워크에서는 싱글 채널 방식과 달리 명시적으로 토폴로지를 형성하기 위한 메커니즘이 요구된다. 본 논문에서는 다중 채널과 블루투스가 탑재된 노드의 이질적 특성을 고려한 스캐터넷(Scatternet) 구성 메커니즘을 제안한다. 본 메커니즘은 칵 노드의 전력 상태와 이동성 정보를 바탕으로 스캐터넷의 마스터와 브리지 노드틀 선택 함으로서 효율적인 네트워크 토플로지를 구성한다.