• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.274-283
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• 2016

The study of maintenance planning is important in military weapon systems because it can improve their availability and reduce the operational and maintenance cost during the total life cycle. In maintenance planning, it is important to determine the preventive maintenance task and its optimal interval. This paper focuses on the hard time task, which is one of the preventive maintenance tasks. A hard time task removes an item or restorative action before some specified maximum age limit to prevent functional failure. The Monte-Carlo simulation model was proposed to help understand the cost effectiveness of a hard time task. In the simulation, various shape parameters of the Weibull distribution and cost ratio of corrective maintenance to preventive maintenance were assumed. Using a Monte-Carlo simulation, a quantified cost saving effect and optimal preventive maintenance interval were suggested.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.17-23
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• 2021

In the present study, a more compact dual-band slot antenna is newly proposed for Wi-Fi application. The proposed antenna is composed of rectangular two stepped slot with open end which can generate standing wave resonance at dual frequency bands and L-type microstrip feed line. The measured impedance bandwidths are 50 MHz(2.412 ~ 2.470 GHz) at low frequency band and 452 MHz(5.451 ~ 5.903 GHz) at high frequency band respectiviely. Furthermore its size of 14 × 21 mm² is reduced by 30% compared to the size of 20 × 21 mm² of a conventional similar compact slot antenna. It has the omni-directional radiation pattern characteristics of a typical dipole antenna on the H-Plane, so it is suitable for commercial wireless network applications such as Wi-Fi.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.645-650
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• 2018

Software stability is the possibility of operating without any malfunction in the operating environment over time. In a finite failure NHPP for software failure analysis, the failure occurrence rate may be constant, monotonically increasing, or monotonically decreasing. In this study, based on the NHPP model and based on the software failure time data, we compared and analyzed the attributes of the software development cost model using the exponential distribution Rayleigh distribution and inverse exponential distribution considering the shape parameter of the Weibull distribution as the life distribution. The results of this study show that the Rayleigh model is the fastest release time and has the economic cost compared to the inverse-exponential model and the Goel-Okumoto model. Using the results of this study, it can be expected that software developers and operators will be able to predict the optimal release time and economic development cost.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.16-19
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• 2014

In this paper, the beacon signals of WiFi doppler frequency detection based WiFi-AP was designed with the subcarrier between a transmitter and a receiver of WLAN(wireless LAN). We can use such signals to identify human moving as an antenna array and tracking of RF beam. This wireless security services with the combination of WiFi doppler frequency and adaptive beacon time signal was proposed for wireless detection and motion based services.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1516-1528
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• 1999

월드 와이드 웹(World Wide Web)에 존재하는 음란성 유해 정보는 많은 국가에서 사회적인 문제를 일으키고 있다. 그러나 현재 음란성 유해 정보로부터 미성년자를 보호하는 실효성 있는 방법은 유해 정보 접근 차단 프로그램을 사용하는 방법뿐이다. 유해 정보 접근 차단 프로그램은 기본적으로 음란성 유해 정보를 포함한 유해 정보 주소 목록을 기반으로 사용자의 유해 정보에 대한 접근을 차단하는 방식으로 동작한다.그런데 대규모 유해 정보 주소 목록의 확보를 위해서는 월드 와이드 웹으로부터 음란성 유해 정보를 자동 색출하는 인터넷 정보 검색 시스템의 일종인 음란성 유해 정보 색출 시스템이 필요하다. 그런데 음란성 유해 정보 색출 시스템은 그 대상이 사람이 아닌 유해 정보 접근 차단 프로그램이기 때문에 일반 인터넷 정보 검색 시스템과는 달리, 대단히 높은 검색 정확성을 유지해야 하고, 유해 정보 접근 차단 프로그램에서 관리가 용이한 검색 목록을 생성해야 하는 요구 사항을 가진다.본 논문에서는 기존 인터넷 정보 검색 모델이 "문헌"에 대한 잘못된 가정 때문에 위 요구사항을 만족시키지 못하고 있음을 지적하고, 월드 와이드 웹 상의 문헌에 대한 새로운 정의와 이를 기반으로 위의 요구사항을 만족하는 검색 모델인 페이지 그룹 검색 모델을 제안한다. 또한 다양한 실험과 분석을 통해 제안하는 모델이 기존 인터넷 정보 검색 모델보다 높은 정확성과 빠른 검색 속도, 그리고 유해 정보 접근 차단 프로그램에서의 관리가 용이한 검색 목록을 생성함을 보인다.Abstract Illegal and Harmful Content on the Internet, especially content for adults causes a social problem in many countries. To protect children from harmful content, A filtering software, which blocks user's access to harmful content based on a blocking list, and harmful content search system, which is a special purpose internet search system to generate the blocking list, are necessary. We found that current internet search models do not satisfy the requirements of the harmful content search system: high accuracy in document analysis, fast search time, and low overhead in the filtering software.In this paper we point out these problems are caused by a mistake in a document definition of the current internet models and propose a new internet search model, Page Group Search Model. This model considers a document as a set of pages that are made for one subject. We suggest a Group Construction algorithm and a Group Evaluation algorithm. And we perform experiments to prove that Page Group Search Model satisfies the requirements.uirements.

• Journal of Korea Entertainment Industry Association
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• v.13 no.5
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• pp.47-57
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• 2019

New product innovation is a key component of a company's survival and sustained growth. With the rapidly changing market environment and global infinite competition, The importance of innovative new product development is growing. In the domestic entertainment industry, Competition is intensifying, and many companies are focusing on developing innovative new products in order to secure continuous competitive advantage in the era of global infinite competition. The problem is that as the intensity of competition increases and the idol production system develops more and more, The costs of planning and marketing are increasing. The fair trade commission estimated the cost of creating an idol group to be about 1 billion won, and some large entertainment companies claim that the investment cost is about 20 ~ 3 billion won. Lean startup is attracting attention as an innovation framework for sustainable competitive advantage of companies. But, there are not many related studies in Korea despite the growing interest. In particular, Case studies that can help to establish specific strategies are limited. Therefore, this study analyzed the successful case of JYP Entertainment's idol singer TWICE who succeeded in new product innovation and suggested practical implications. Theoretically, This study extended the Lean startup to the entertainment industry and suggested practical implications as the basic data for establishing the innovation strategies for the idol singers of domestic entertainment companies.

• Convergence Security Journal
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• v.8 no.2
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• pp.35-40
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• 2008

Software failure time presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing. For data analysis of software reliability model, data scale tools of trend analysis are developed. The methods of trend analysis are arithmetic mean test and Laplace trend test. Trend analysis only offer information of outline content. In this paper, we discuss forecasting failure time case of failure time censoring. The used software failure time data for forecasting failure time is random number of Weibull distribution(shaper parameter 1, scale parameter 0.5), Using this data, we are proposed to ARIMA(AR(1)) and simulation method for forecasting failure time. The practical ARIMA method is presented.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.37-41
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• 2016

In this paper, we propose a fire alarm system that utilizes Wi-Fi to alarm multiple people at once. This system, based on Arduino, uses smoke, flame and temperature sensor units to sense fire and send detection data to a server via wireless communication system. The server uses stored data to relay current fire situations gathered from nearby sensors to smartphones. It also automatically reports the fire using location data from sensors. Using this system, we were able to retrieve fire alarm from sensors via push notification of our smartphone. We also confirmed the establishment of linkage with sensors and automatic report of fire via SMS. From this result, the possibility of sending real-time notifications via the Internet toward nearby smartphones about disasters such as conflagration has been proven to be feasible.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.44-51
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• 2017

Recently, the parking in downtown area has caused severe problem due to the dramatic increase of possessing automobile in the country. A parking structure has been on the spotlight to solve the parking problem in downtown area. However, the overall height of parking structure is stipulated less than 8 m. Therefore, in this research, 'wide composite beam', which is possible for reducing story height and having long span, is developed and the flexural capacity of the wide composite beam is evaluated. Based on the result of the flexural test, the flexural strength of wide composite beam increased by 20% as the thickness of steel beam increased by 3 mm ($6mm{\rightarrow}9mm$) The shapes of rebar (whether it is triangle or rectangular shape) in the wide composite beam did not affect its flexural strength. The flexural strength of wide composite beam without rebar decreased by 10% compared to that of wide composite beam with rebar. In addition, the neutral axis moved upward as a load increased, but the neutral axis moved downward, when the load exceeded a certain level of load.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.187-190
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• 2015

Recently, most of people wants to have smart life for themselves like smart phones. In this paper, we propose the smart elevator based on the laser screen, speakers and air fresheners. Using this elevator, we could enjoy the various screen inside, and we could keep contacting with manager for wifi in the emergency situation. Also, the elevator could be operated with user's motion for Kinect. Finally, we did the survey for understanding preference of smart elevator. The grops are elevator manufacturing company, elevator distribution corporation and consumers, each group have 200 people.