• 반도체디스플레이기술학회지
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• 제12권2호
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• pp.51-56
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• 2013

Even if transmissions through normal channel between ubiquitous devices and terminal readers are encrypted, any extra sources of information retrieved from encrypting module can be exploited to figure out the key parameters, so called side channel attack. Since side channel attacks are based on statistical methods, making side channel signal weak or complex is the proper solution to prevent the attack. Among many countermeasures, shielding the electromagnetic signal and adding noise to the EM signal were examined by applying different thicknesses of thin films of ferroelectric (BTO) and conductors (copper and gold). As a test vehicle, chip antenna was utilized to see the change in radiation characteristics: return loss and gain. As a result, the ferroelectric BTO showed no recognizable effect on both shielding and adding noise. Cu thin film showed increasing shielding effect with thickness. Nanometer Au exhibited possibility in adding noise by widening of bandwidth and red shifting of resonating frequencies.

• Journal of Communications and Networks
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• 제17권1호
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• pp.1-11
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• 2015

In this paper, the transmission of an improper-complex second-order stationary data sequence is considered over a strictly band-limited frequency-selective channel. It is assumed that the transmitter employs linear modulation and that the channel output is corrupted by additive proper-complex cyclostationary noise. Under the average transmit power constraint, the problem of minimizing the mean-squared error at the output of a widely linear receiver is formulated in the time domain to find the optimal transmit and receive waveforms. The optimization problem is converted into a frequency-domain problem by using the vectorized Fourier transform technique and put into the form of a double minimization. First, the widely linear receiver is optimized that requires, unlike the linear receiver design with only one waveform, the design of two receive waveforms. Then, the optimal transmit waveform for the linear modulator is derived by introducing the notion of the impropriety frequency function of a discrete-time random process and by performing a line search combined with an iterative algorithm. The optimal solution shows that both the periodic spectral correlation due to the cyclostationarity and the symmetric spectral correlation about the origin due to the impropriety are well exploited.

• International Journal of Knowledge Content Development & Technology
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• 제9권3호
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• pp.23-41
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• 2019

This study combines the concept of degree centrality in complex network with the Term Frequency $^*$ Proportional Document Frequency ($TF^*PDF$) algorithm; the combined method, called PMCN (PDF-Modified similarity and Complex Network), constructs relationship networks among sentences for writing news summaries. The PMCN method is a multi-document summarization extension of the ideas of Bun and Ishizuka (2002), who first published the $TF^*PDF$ algorithm for detecting hot topics. In their $TF^*PDF$ algorithm, Bun and Ishizuka defined the publisher of a news item as its channel. If the PDF weight of a term is higher than the weights of other terms, then the term is hotter than the other terms. However, this study attempts to develop summaries for news items. Because the $TF^*PDF$ algorithm summarizes daily news, PMCN replaces the concept of "channel" with "the date of the news event", and uses the resulting chronicle ordering for a multi-document summarization algorithm, of which the F-measure scores were 0.042 and 0.051 higher than LexRank for the famous d30001t and d30003t tasks, respectively.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.71-76
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• 2007

Flow visualization of a droplet passing through a straight channel and a diverging channel has been carried out using micro-PIV. Diverging channel is frequently used in lab-on-a-chip and microfluidic devices, where flow pattern inside the droplet passing is quite different from that through a straight channel. In the present study, we visualized the droplet flow in three different regions. The first region is where the droplet has a wide contact area with the channel wall, the second region is characterized with a narrow contact area and the third region is where droplet is detached from the channel wall. Visualization results show that the internal flow inside the droplet passing through the straight channel moves in the opposite direction to the droplet velocity in the near wall exhibiting complex flow patterns. But in the diverging channel the internal flow inside the droplet moves in the same direction as the droplet velocity due to the shear induced by oil phase flow exhibiting rather simple flow pattern.

• 한국자기공명학회논문지
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• 제3권2호
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• pp.109-126
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• 1999

The location of Cu(II) exchanged into measoporous aluminosilicate MCM-41(AlMCM-41) material and its interaction with various adsorbate molecules were investigated by electron spin resonance and electron spin echo modulation spectroscopies. Cu(II) is fully coordinated to adsorbates in a wide open mesopore of AlMCM-41 for the formation of favorable complexes. It was found that in the fresh hydrated material, Cu(II) is octahedrally coordinated to six water molecules as evidenced by an isotropic room temperature ESR signal. This species is located in a cylindrical MCM-41 channel and rotates rapidly at room temperature. Evacuation at room temperature removes some of these water molecules, leaving the Cu(II) coordinated to less water molecules and anchored to oxygens in an MCM-41 channel wall. Dehydration at 450$^{\circ}C$ produces one Cu(II) species located on the internal wall of a channel, which is easily accessible to adsorbates. Adsorption of adsorbate molecules such as water, methanol, ammonia, pyridine, aniline, acetonitrile, benzene, and ethylene on a dehydrated Cu-AlMCM-41 material causes changes in the ESR spectrum of Cu(II), indicating the complex formation with these adsorbates. Cu(II) forms a complex with six molecules of methanol as evidenced by an isotropic room temperature ESR signal and ESEM analysis like upon water adsorption. Cu(II) also forms a square planar complex containing four molecules of N-containing adsorbates such as ammonia, pyridine and aniline based on resolved nitrogen superhyperfine interaction and their ESR parameters. However, Cu(II) forms a complex with six-molecules of acetonitrile based on ESR parameters. Only one molecule of benzene or ethylene is coordinated to Cu(II).

• 대한전자공학회논문지TC
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• 제48권10호
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• pp.53-59
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• 2011

최근 들어, 이동통신 서비스가 광범위가 사용되고 서비스 지역이 확대됨에 따라 서비스 품질 유지를 위한 서비스 영역의 확장이 요구 되어 짐에 따라 중계기의 역할은 계속적으로 증가하고, 비교적 설치가 용이하고 위치 제약이 적으며, 비용 측면에서 운영 비용이 절감되는 ICS(Interference Cancellation System) 중계기가 요구되어진다.. 하지만 적용되어지는 적응 알고리즘의 필터 업데이트 시 연산량의 증가로 인해 하드웨어 복잡도가 증가하게 되어 구현 시 많은 어려움이 따른다. 본 논문에서는 궤환되는 경로가 존재하는 경우. 기저대역 신호처리를 활용한 ICS 중계기에서 궤환 간섭 신호를 제거를 위한 연산량이 대폭줄여 하드웨어 복잡성을 감소시키는 Complex Signed sign LMS 적응 알고리즘을 제안한다. 제안된 알고리즘의 성능 평가를 위해 Static 채널 환경 하에서 WCDMA 신호를 이용하여 ICS 시스템에 대한 알고리즘을 모의 실험 한 결과, 수렴속도 및 수렴 오차 측면에서 우수한 성능을 통해 구현시 요구되어지는 연산량을 크게 줄여 하드웨어 복잡도를 줄일 수 있는 효과를 볼 수 있게 되었다.

• 생물환경조절학회지
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• 제8권3호
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• pp.209-215
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• 1999

수로형의 양어시설에서 틸라피아 사육시 성장도 및 사육수의 수질을 파악하여 수경재배시설에 수로형 사육시설의 병용 가능성을 조사하고, 펜타이트 파이프를 이용한 간이 수로형사육시설을 개발하고자 시험을 수행하였다. 폭 2m, 높이 1m,길이 19m의 수로형 사육시설 위에 수경 베드를 설치하고 틸라피아를 양식하였다. 수질은 사육하는데 이상 없이 유지되었고, 수로형 시설에서의 틸라피아의 성장은 원형사육시설에서의 그 것과 대등하였다. 따라서 수경재배시설에 수용할 수 있는 양어시설은 수로형이 적합하며 사육환경이 정상적이므로 수로형 사육시설의 도입이 가능하다고 판단되었다. 또한 양어수경 복합영농어시설은 높이 1 m, 폭 1.4 m, 길이 20 m의 크기로, 기둥은 25mm의 펜타이트 파이프와 사육조는 5m의 PP판넬을 사용하도록 하였으며, biofilter로는 모래를 10cm 정도 채워 작물을 재배하도록 하는 간이수로형 양어수경 복합시설의 구조를 고안하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1807-1812
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• 2004

Sinusoidal wavy channel is one of the most commonly used devices in the industry for achieving mixing and heat transfer. Here we report on results obtained from the DNS of flow inside the wavy channel performed using the finite volume technique. As a primary stage to obtain the optimal design for heat transfer and mixing, this study observed the basic flow structures in a wavy channel. The mass flow rate is kept constant with friction Reynolds number of $Re_{\tau}$ = 140 . Time- and space-averaged and instantaneous flow fields are illustrated to observe the flow structures. Although the direct comparison of results between turbulent wavy and flat channel is somehow difficult due to the different flow phenomena derived from different configuration, here the mean streamwise velocity and RMS of velocities at same $Re_{\tau}$ of two different channels are compared. The basic difference between wavy and flat channel flow is the existence of small scale wall vortices along the walls in a wavy channel. These vortices make flow more complex, which will accompany the increase of heat transfer, pressure drop and drag.

• The Journal of the Acoustical Society of Korea
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• 제17권1E호
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• pp.36-43
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• 1998

A fuzzy logic filter is constructed from a set of fuzzy IF-THEN rules which change adaptively to minimize some criterion function as new information becomes available. This paper generalizes the fuzzy logic filter and it's adaptive filtering algorithm to include complex parameters and complex signals. Using the complex Stone-Weierstrass theorem, we prove that linear combinations of the fuzzy basis functions are capable of uniformly approximating and complex continuous function on a compact set to arbitrary accuracy. Based on the fuzzy basis function representations, a complex orthogonal least-squares (COLS) learning algorithm is developed for designing fuzzy systems based on given input-output pairs. Also, we propose an adaptive algorithm based on LMS which adjust simultaneously filter parameters and the parameter of the membership function which characterize the fuzzy concepts in the IF-THEN rules. The modeling of a nonlinear communications channel based on a complex fuzzy is used to demonstrate the effectiveness of these algorithm.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.624-627
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• 2007

There are many channel confluences existing in natural river systems, where the hydraulics are very complex because of the interactive between tributary and main river The RMA-2 model Is applied in this paper to model the confluence between Uksu Chun subriver and Nam Chun main river. Based on three types of assumed confluence forms, the model resuits present the hydraulics at channel confluence can be divided into several zones including a zone of separation immediately downstream of the junction branch channel, a maximum and minimum velocity region at upstream and downstream in the confluent channel, and a shear plane developed between the two combing flows at downstream of confluent channel. And the different types of confluent forms performs a very high effect on drainability of tributary, so it is very necessary to design a reasonable confluent forms.