• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.221-228
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• 2015

To protect and manage the Korean space assets including satellites, it is important to have precise positions and orbit information of each space objects. While Korea currently lacks optical observatories dedicated to satellite tracking, the Korea Astronomy and Space Science Institute (KASI) is planning to establish an optical observatory for the active generation of space information. However, due to geopolitical reasons, it is difficult to acquire an adequately sufficient number of optical satellite observatories in Korea. Against this backdrop, this study examined the possible locations for such observatories, and performed simulations to determine the differences in precision of optical orbit estimation results in relation to the relative baseline distance between observatories. To simulate more realistic conditions of optical observation, white noise was introduced to generate observation data, which was then used to investigate the effects of baseline distance between optical observatories and the simulated white noise. We generated the optical observations with white noise to simulate the actual observation, estimated the orbits with several combinations of observation data from the observatories of various baseline differences, and compared the estimated orbits to check the improvement of precision. As a result, the effect of the baseline distance in combined optical GEO satellite observation is obvious but small compared to the observation resolution limit of optical GEO observation.

• 호남수학학술지
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• 제20권1호
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• pp.97-109
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• 1998

We first obtain the white noise calculus to the computation of Feynman integral for a generalized function, according to the definition of Feynman integrals by T. Hida and L. Streit. We next give the translation theorem for Feynman integral of a generalized function.

• 한국정밀공학회지
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• 제31권7호
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• pp.605-613
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• 2014

Scanning white-light interferometry is an important measurement option for many surfaces. However, serious profile measurement errors can be present when measuring free-form surfaces being highly curved or tilted. When the object surface slope is not zero, the object and reference rays are no longer common path and optical aberrations impact the measurement. Aberrations mainly occur at the beam splitter in the interference objective and from misalignment in the optical system. Both effects distort the white-light interference signal when the surface slope is not zero. In this paper, we describe a modified version of white-light interferometry for eliminating these measurement errors and improving the accuracy of white-light interferometry. Moreover, we report systematic errors that are caused by optical aberrations when the object is not flat, and compare our proposed method with the conventional processing algorithm using the random ball test.

• 영어영문학
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• 제64권2호
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• pp.239-252
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• 2018

Many critics on William Faulkner's As I Lay Dying have read Addie Bundren as the disrupter of patriarchal power. By raising a question about the usefulness of language, which is the symbolic power of patriarchy and having an affair with the preacher Whitfield outside her wedlock, Addie directly challenges patriarchal power. From a quite different vantage point, however, we can read Addie as the faithful protector of the norm of whiteness in the South in light of the social hierarchy. As a former school teacher, Addie is from middle class before her marriage. By her marriage to Anse, who is a lower-class white, Addie has class anxiety that her social status in the stratum of whiteness could be degraded from a middle to a lower-class white, "white trash," which means that she is not white enough to be considered as the normative whiteness. Especially, Addie's anxiety increases due to the fact that her lazy husband is reluctant to work and relies on her neighbors, causing her family to be entrapped at the bottom in the stratum of whiteness. Therefore, she decides to take revenge on her husband after giving birth to her second child Darl by asking Anse to bury her dead body in her familial burial site in Jefferson. By rendering her family to suffer the hardship during her funeral procession, not only does she succeed in taking revenge on Anse on the surface, she regains her social status as a middle-class white by being buried in Jefferson fundamentally.

• 한국통신학회논문지
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• 제37B권11호
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• pp.1050-1057
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• 2012

Super Wi-Fi는 TV white space 대역을 이용하여 Wi-Fi 네트워크를 구성하는 무선 인터넷 서비스 기술이다. 하지만, TV white space 대역 이용자는 기존 ISM 대역에서와 달리 incumbent user가 활성화될 때마다 Super Wi-Fi로 사용 중인 채널을 양보해야 하므로 Wi-Fi 서비스의 연속성을 보장하기 어렵다. 본 논문에서는 Super Wi-Fi 서비스 영역에서 AP (access point)가 운용채널을 비워 주어야 할 때 다른 이용 가능한 TV 채널을 AP의 운용채널로 선택하고 이 결과를 MS (mobile station)에게 제공함으로써 Wi-Fi의 서비스의 연속성이 보장될 수 있는 방법을 제시하였다. 즉, AP의 운용채널에 incumbent user가 나타나면 즉시 운용채널을 비우지 않고 incumbent user에 간섭을 주지 않는 subcarrier들의 그룹인 active subchannel을 이용하여 MS에게 AP 자신이 운용할 다른 채널의 정보를 제공한다. 이 채널정보를 공유한 MS는 AP의 운용할 다른 채널로 빠른 채널 핸드오버를 할 수 있으므로 Super Wi-Fi 서비스 연속성 보장성능이 향상될 수 있다. 제시한 채널 핸드오버 방법을 기존 Wi-Fi 방법과 비교하여 핸드오버 지연시간이 개선됨을 확인하였다.

• 한국멀티미디어학회논문지
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• 제15권7호
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• pp.903-909
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• 2012

본 논문에서는 TV 주파수 대역내의 인접채널간 다른 통신 시스템들의 공존을 위한 공유 성능을 분석하였다. 간섭 송신기의 다양한 밀도와 전송출력에 따른 파라미터 성능 결과를 분석하였다. 각 시스템간의 간섭 영향을 고려하기 위해, 두 경우가 분석되었다. 첫째로, 간섭시스템이 WiBro, 희생시스템이 WLAN인 경우와 두 번째로 간섭원이 WLAN이고 희생원이 WiBro인 경우이다. 채널 환경으로는 자유공간모델, Extended Hata, IEEE 802.11 모델을 이용하였다. 분석된 다양한 공유시나리오에서의 상호 공존 결과는 향후 인접 주파수 환경에서 다양한 통신 프로토콜을 이용하는 무선기기에 대한 상호 공존 조건을 마련하는 기술개발에 활용할 수 있을 것이다.

• 영어영문학
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• 제58권6호
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• pp.1023-1039
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• 2012

The rising urban space in the United States at the turn of the twentieth century was an exemplary site of struggles between the dominant white population and those who migrated from the imperial peripheries. By setting up the space of Chinatown as a segregated sphere within the urban space, the dominant white American society attempted to recreate the sense of distance between themselves and the racial "others." Accordingly, the dominant narrative representations of San Francisco Chinatown at the turn of the century endeavored to produce and maintain the spatial dichotomies between the orderly spaces of natives and the disruptive immigrant communities within the larger boundary of modern American city space. As a Eurasian woman writer, Sui Sin Far attempted to provide distinctive portrayals of the space of Chinatown and its inhabitants that were far different from those of her contemporaries. Through her portrayals of San Francisco Chinatown in her collection of short-stories, Mrs. Spring Fragrance and Other Writings (1912), Far challenges against the false stereotypes and misreading of this unique immigrant space within and efforts to present the Chinatown as a heterotopic diaspora space where the "insiders" and the "outsiders" of the American urban space intermingle and influence each other.

• 정보와 통신
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• 제30권5호
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• pp.88-94
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• 2013

본고에서는 TV White Space (TVWS) WPAN 표준 기술 동향을 알아본다. TVWS WPAN의 표준화가 진행중인 IEEE 802.15.4m의 표준화 현황과 현재 진행중인 표준 전송기술 (TVWS-FSK, TVWS-OFDM, TVWS-NB-OFDM), 그리고 표준화 완료 시 적용될 수 있는 응용 분야에 대해서 서술하였다.

• 조명전기설비학회논문지
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• 제27권1호
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• pp.1-9
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• 2013

The experimental study of the white LED lighting focused on the readability in interior space according to age group is conducted realizing importance of the lighting environment and necessity of lighting study depending on the user situation. The results of study represent that a teenager does not show sensitive reaction to change of the color temperature and illuminance. The people in 20s and 30s prefer neutral white LED lighting and are very sensitive to change of the light environment. The people in 50s and 60s prefer high illumination and cool white LED lighting series. People of all ages highly appraise 6000K of 700 lux and 4000K in the illuminance range of 700 lux to 1000 lux for readability. The white LED lighting of color temperature 4000K is estimated as a suitable environment for readability in a wide range of illumination.

• Journal of Communications and Networks
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• 제16권2호
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• pp.238-244
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• 2014

A key technical challenge in TV white spaces is the efficient spectrum usage without interfering with primary users. This paper considers available spectrum discovery scheme using in-band sensing signal to support super Wi-Fi services effectively. The proposed scheme in this paper adopts non-contiguous orthogonal frequency-division multiplexing (NC-OFDM) to utilize the fragmented channel in TV white space due to microphones while this channel cannot be used in IEEE 802.11af. The proposed solution is a novel available spectrum discovery scheme by exploiting the advantages of a sensing signaling. The proposed method achieves considerable improvement in throughput and delay time. The proposed method can use more subcarriers for transmission by applying NC-OFDM in contrast with the conventional IEEE 802.11af standard. Moreover, the increased number of wireless microphones (WMs) hardly affects the throughput of the proposed method because our proposal only excludes some subcarriers used by WMs. Additionally, the proposed method can cut discovery time down to under 10 ms because it can find available channels in real time by exchanging sensing signal without interference to the WM.