• ETRI Journal
• /
• 제41권2호
• /
• pp.176-183
• /
• 2019

Spectrum sensing plays an important role in spectrum sharing. Energy detection is generally used because it does not require a priori knowledge of primary user (PU) signals; however, it is sensitive to noise uncertainty. An order statistics (OS) detector provides inherent protection against nonhomogeneous background signals. However, no analysis has been conducted yet to apply OS detection to spectrum sensing in a wireless channel to solve noise uncertainty. In this paper, we propose a robust spectrum sensing scheme based on generalized order statistics (GOS) and analyze the exact false alarm and detection probabilities under noise uncertainty. From the equation of the exact false alarm probability, the threshold value is calculated to maintain a constant false alarm rate. The detection probability is obtained from the calculated threshold under noise uncertainty. As a fusion rule for cooperative spectrum sensing, we adopt an OR rule, that is, a 1-out-of-N rule, and we call the proposed scheme GOS-OR. The analytical results show that the GOS-OR scheme can achieve optimum performance and maintain the desired false alarm rates if the coefficients of the GOS-OR detector can be correctly selected.

• 디지털융복합연구
• /
• 제17권8호
• /
• pp.465-470
• /
• 2019

본 연구는 남자 일반부 K-1 1000m 결승 경기의 랩타임을 분석하여 경기력 향상을 위한 구간별 페이스 조절 전략을 모색하기 위해 실시되었다. 이를 위해 99회 전국체전 결승 경기의 랩타임을 250m 단위 구간으로 측정하였으며, 이 기록을 2018년도에 개최된 World Championship 남자 일반부 결승 경기의 랩타임 자료와 비교 분석하였다. 국내 최상위 선수들의 최종 기록 평균은 248.651초, 국제무대 최상위 선수들은 210.826초로 38초가량 경기력 차이가 난다. 랩타임별로는 250m 구간마다 8초, 11초, 6초, 13초 뒤처지는 기록을 나타냈다. World Championship 참가 선수들은 Fast-Maintain-Maintain-Spurt 전략을 쓰는 반면, 국내 선수들은 Fast-Slow-Fast-Slow의 페이스 조절 전략을 주로 쓰고 있었다. 국내 선수들은 경기력 향상을 위해, '빠른 스타트에 이은 중반 페이스 유지, 마지막 스퍼트'로의 전반적인 페이스 조절 전략 수정이 필요하다.

• 소음진동
• /
• 제3권1호
• /
• pp.47-55
• /
• 1993

In order to maintain comfortable life environment around railroad site, noise from train itself, and to train & rail interaction, and the vibration transmitted through the ground should be controlled to the extent of permissible level. In order to achieve this, the basic railroad noise & vibration data such as magnitude and frequency characteristics of them are necessary to establish the counterplan for railroad noise & vibration. In this study, we measured and analysed the characteristics of time variation, frequency, direction and distance attenuation of noise and vibration of the railroad between Seoul and Pusan.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1992년도 춘계학술대회 논문집
• /
• pp.237-241
• /
• 1992

Error calibration and frequent reverification of coordinate measuring machines(CMMs) and machine tools are currently acknowledge as essential processes in order to maintain high performance of the machines and high quality of products. This paper shows a micro computer integrated circular error calibration system, which is fast and efficient error calibration system

• 가정과삶의질연구
• /
• 제34권3호
• /
• pp.45-64
• /
• 2016

In order to understand Korean American immigrants'adjustment to American society, it is important to understand how their life rituals and ethnic identities maintain or change over time and across immigration generations. To achieve this goal, this study examined how Korean Americans who resided in the New York City metropolitan area and New Jersey State performed life rituals and formed ethnic identities. A total of 18 Korean immigrants participated in one-on-one in-depth interviews and the interview data were analyzed with the themes. The results showed that Korean Americans performed life rituals integrating both Korean and American cultural aspects. Many Korean Americans attempted to perform life rituals based on American cultural holidays and procedures. However, a majority of these Koreans also strived to maintain Korean ethnic identities and also practice traditionally Korean life rituals as a way to preserve this ethnic identity. These findings suggest that across time and generation, Korean Americans prefer to maintain their Korean cultural identity, while not shunning the adoption of typical "American" rituals. The way that Korean Americans practice and develop identities differs very little across immigration generation. These findings provide insight on how the Korean government may support foreigners and immigrant families in South Korea and Korean Americans' acculturation processes in the U.S.

• 한국식생활문화학회지
• /
• 제33권4호
• /
• pp.354-362
• /
• 2018

With increasing interest in the health and safety of food served in restaurants, more emphasis is being placed on the importance of health and food. As a result, Yaksun cuisine with new added effects and image is becoming more popular as a way to improve people's health. This study analyzed the effects of selection attributes relating to Yaksun cuisine on customer satisfaction and intention to maintain relationship in order to understand various needs of consumers as they relate to health food. The results showed that, among selection attributes of Yaksun cuisine, price, safety, and health were found to have significant effects on customer satisfaction; however, the effect of quality on satisfaction was not verified. Moreover, while the effect of safety and health of Yaksun cuisine on the intention to maintain relationship was found to be significant, the effects of quality and price on the intention to maintain relationship were not verified. These findings suggest that consumers believe Yaksun cuisine is more beneficial for health than general food and trust the origin label, hygiene, and safety of ingredients in Yaksun cuisine. Therefore, the results of this study suggests providing opportunities for consumers to experience diverse tastes in Yaksun cuisine and that development and promotion of different recipes using Yaksun ingredients will help reinforce competitiveness of Yaksun cuisine in the market and increase sales.

• 한국정밀공학회지
• /
• 제22권8호
• /
• pp.192-198
• /
• 2005

In this paper, we propose a new training system for the improvement of equilibrium sense using unstable platform. The equilibrium sense, which provides orientation with respect to gravity, is important to integrate the vision, somatosensory and vestibular function to maintain the equilibrium sense of the human body. In order to improve the equilibrium sense, we developed the software program such as a block game, pingpong game using Visual C++. These training system for the equilibrium sense consists of unstable platform, computer interface and software program. The unstable platform was a simple structure of elliptical-type which included tilt sensor, wireless RF module and the device of power supply. To evaluate the effect of balance training, we measured and evaluated the parameters as the moving time to the target, duration to maintain cursor in the target of screen and the error between sine curve and acquired data. As a results, the moving time to the target and duration to maintain cursor in the target was improved through the repeating training of equilibrium sense. It was concluded that this system was reliable in the evaluation of equilibrium sense. This system might be applied to clinical use as an effective balance training system.

• 상하수도학회지
• /
• 제20권5호
• /
• pp.701-707
• /
• 2006

Disinfectant residual should be maintained to achieve biological stability during distribution of treated water. The wide distribution of retention times associated with storage and transport of water in a network and the reactivity of disinfectants make it difficult to maintain adequate residuals at critical locations. Rechlorination at some intermediate locations may reduce the total disinfectant dose while keeping residuals within specified limits throughout the water distribution system. In order to select the adequate location of rechlorination for achieving to maintain of residual chlorine throughout the distribution system, EPANET was used in this study. EPANET was well predicted chlorine transport and residual loss in the distribution system. Location of rechlorination was selected to maintain 0.4mg/L of residual chlorine throughout a water distribution system by field investigation and model simulation. The quantity of chlorine may reduced 36.7% and provided smooth residual between 0.42 and 0.60mg/L, when rechlorination would be used continuously at strategic location within the distribution system.

• 대한조선학회논문집
• /
• 제52권3호
• /
• pp.206-221
• /
• 2015

Supercavitation is a modern technique which can be used to surround an underwater vehicle with a bubble in order to reduce the resistance of the vehicle. When the vehicle is at low speed in the deep sea, the cavitation number is relatively big and it is difficult to generate a cavity large enough to envelope the vehicle. In this condition, the artificial cavity, called ventilated cavity, can be used to solve this problem by supplying gas into the cavity and can maintain supercavitating condition. In this paper, a relationship between the ventilation gas supply rate and the cavity shape is determined. Based on the relationship a ventilation rate control is developed to maintain the supercavitating state. The performance of the ventilation control is verified with a depth change control. In addition, dynamics modeling for the supercavitating vehicle is performed by defining forces and moments acting on the vehicle body in contact with water. Simulation results show that the ventilation control can maintain the supercavity of an underwater vehicle at low speed in the deep sea.

• 한국치위생학회지
• /
• 제13권1호
• /
• pp.146-157
• /
• 2013

Objectives : The purpose of this paper is to analyze the effects of short-term oral health care on children at community care centers, in order to allow them to maintain good oral health. Methods : The SPSS (Statistical Package for Social Science), Window Version 18.0 was used to analyze the data for the children's present conditions of oral health; their ability to maintain good oral health; their general knowledge about oral health; changes in their oral health awareness; habit formations concerning oral health; and the satisfaction level of oral health education. Results : 1. While the average number of teeth before the program is 19.84(6.19), that of teeth after the program is 21.33(6.10). 2. Average test scores on oral health information of post-program are improved more than those of pre-program. 3. The 8th measurement of O'Leary plaque index is 3.27, which shows significant changes. 4. Satisfaction level with the program is 4.75(0.45), which shows that children are satisfied with the program. Conclusions : The paper shows that in order to maintain the oral health of children at community care centers, their habit formation and practice for the oral health is important. It also shows that cooperation among communities and public health centers is important to develop various oral health education programs like the program.