• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.229-232
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• 2000

Orthogonal frequency division multiplexing(OFDM) has meanwhile become part of several telecommunicati ons standards, such as satellite and terrestrial digital audio broadcasting(DAB), digital terrestrial TV broad casting(DVB), asymmetric digital subscriber line(ADSL) for high-bit-rate digital subscriber services on twisted-pair channels, and broadband indoor wireless systems. In his paper, we show that OFDM signals contain sufficient structure to accomplish blind channel estimation using second order statistics only. This method doesn't require redundancy as cp in transmitter. And the result is compared with PSAM channel estimation as least square, linear minimum mean square, singular value decomposition.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.101-105
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• 2005

본 논문에서는 LVQ(Learning Vector Quantization)을 퍼지화한 새로운 퍼지 학습 법칙을 제안하였다. 퍼지 LVQ 학습 법칙 3은 기존의 학습률 대신에 퍼지 학습률을 사용하였는데, 기존의 LVQ와는 달리 비대칭인 학습률을 사용하였다. 기본의 LVQ에서는 분류가 맞거나 틀렸을 때 같은 학습률을 사용하고 부호만 달랐으나, 새로운 퍼지 학습 법칙에서는 분류가 맞거나 틀렸을 때 부호가 다를 뿐만 아니라 학습률도 다르다. 이 새로운 퍼지 학습 법칙을 무감독 신경회로망인 improved IAFC(Integrated Adaptive Fuzzy Clustering) 신경회로망에 적용하여 감독 신경회로망으로 변형하였다. Improved IAFC 신경회로망은 유연성이 있으면서도 안정성이 있다. 제안한 supervised IAFC 신경회로망 3의 성능과 오류 역전파 신경회로망의 성능을 비교하기 위하여 iris 데이터를 사용하였는데 Supervised IAFC 신경회로망 3가 오류 역전파 신경회로망보다 성능이 우수하였다.

• Journal of the Korean Statistical Society
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• v.35 no.1
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• pp.63-77
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• 2006

Maximum product of spacings estimator is proposed in this paper as a competent alternative of maximum likelihood estimator for the parameters of exponentiated-Weibull distribution, which does work even when the maximum likelihood estimator does not exist. In addition, a Bayes type estimator known as generalized maximum likelihood estimator is also obtained for both of the shape parameters of the aforesaid distribution. Though, the closed form solutions for these proposed estimators do not exist yet these can be obtained by simple appropriate numerical techniques. The relative performances of estimators are compared on the basis of their relative risk efficiencies obtained under symmetric and asymmetric losses. An example based on simulated data is considered for illustration.

• Journal of information and communication convergence engineering
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• v.13 no.3
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• pp.189-196
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• 2015

In this paper, we present a rotating auto-zeroing offset cancellation technique, which can improve the performance of touch screen sensing circuits. Our target touch screen detection method employs multiple continuous sine waves to achieve a high speed for large touch screens. While conventional auto-zeroing schemes cannot handle such continuous signals properly, the proposed scheme does not suffer from switching noise and provides effective offset cancellation for continuous signals. Experimental results show that the proposed technique improves the signal-to-noise ratio by 14 dB compared to a conventional offset cancellation scheme. For the realistic simulation results, we used Cadence SPECTRE with an accurate TSP model and noise source. We also applied an asymmetric device size (10% MOS size mismatch) to the OP Amp design in order to measure the effectiveness of offset cancellation. We implemented the proposed circuit as part of a touch screen controller system-on-chip by using a Magnachip/SK Hynix 0.18-µm complementary metal-oxide semiconductor (CMOS) process.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.5947-5954
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• 2012

The cancer stem cell (CSC) model states that cancers are organized in cellular hierarchies, which explains the functional heterogeneity often seen in tumors. Like normal tissue stem cells, CSCs are capable of self-renewal, either by symmetric or asymmetric cell division, and have the exclusive ability to reproduce malignant tumors indefinitely. Current systemic cancer therapies frequently fail to eliminate advanced tumors, which may be due to their inability to effectively target CSC populations. It has been shown that embryonic pathways such as Wnt, Hedgehog, and Notch control self-renewal and cell fate decisions of stem cells and progenitor cells. These are evolutionary conserved pathways, involved in CSC maintenance. Targeting these pathways may be effective in eradicating CSCs and preventing chemotherapy or radiotherapy resistance.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.74-75
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• 2000

WDM(wavelength-division multiplexing) 광통신 네트웍을 이루는 핵심기술중의 하나는 ADF(Add-drop Filter)의 구현에 있다. 광섬유격자와 여러형태의 구조를 이용한 ADF들 중에서도 비대칭 결합기와 광섬유 격자를 이용한 구조는, 간섭계 구조가 아니기 때문에 제작이 용이하고 보다 안정된 특성을 보일 것으로 기대되어 많은 관심을 갖게 하고 있다$^{(1)}$ . 비대칭 결합기 구조의 경우, 두 광도파로의 코어반경이나 굴절율 분포가 서로 다르기 때문에, 일반적으로 광파의 결합이 일어나지 않는다. 그러나 브래그 격자의 반사조건을 만족하는 파장성분의 경우 입력단(input port)에서 드롭단(drop port)으로 반사되어 나오고, 그 외의 파장성분은 출력단(Output port)으로 나오게 되어 드롭 기능을 수행하게 된다. 비슷한 원리로 add port에서 출력단으로의 add 기능도 수행된다. 본 논문에서는 연산자 분리 시영역 모델$^{(2)}$ 을 이용하여 비대칭구조에서의 파장응답 특성을 해석하였다. 또한 최적화를 위한 조건을 알아 보고, 소자 설계에 필요한 파라미터를 정의하여 최적설계에 필요한 파라미터를 구하였다. (중략)

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.2
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• pp.161-164
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• 2004

The yo-yo system has been introduced as an interesting plant to demonstrate the effectiveness of intelligent controllers. Having nonlinear and asymmetric characteristics, the yo-yo plant requires a controller quite different from conventional controllers such as PID. In this paper is presented an adaptive method of controlling the yo-yo system. Fuzzy logic controller based on human expertise is referred at first. Then, an adaptive fuzzy controller which has adaptation features against the variation of plant parameters is proposed. Finally, experimental results are presented.

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.418-421
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• 2006

In this study, we surveyed the influence of IOA (iodoacetamide) and media upon protoplast fusion for the efficient production of the somatic hybrid among S. sisymbriifolium and other Solanum species (S. intergrifolium and S. toxicarium). Regardless of a breed, as the IOA concentration increases, the cell division tends to decrease. As the influence of the media on the colony formation, we could get 5 colonies from the fusion of S. sisymbriifolium and IOA-treated S. integrifolium protoplast, but none was observed in other fusions. As a result of analyzing their IDH isozyme, we found a somatic hybrid in 2 objects.

• Structural Engineering and Mechanics
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• v.25 no.4
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• pp.423-444
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• 2007

By using the incremental form of the endochronic theory of plasticity, a model of material function is proposed in this paper to investigate plastic behavior. By comparing the stress-strain hysteresis loop, the theory is shown to agree well with the experimental results, especially in the evolution of peak stress values of SAE 4340 steel loaded by cyclic loading with various amplitudes. Depending on the choice of material parameters, the present model can substantially result in six categories of material function, each of which can behave differently with respect to an identical deformation history. In addition, the present model of material function is shown to be capable of describing the behavior of erasure of memory of materials, as experimentally observed by Lamba and Sidebottom (1978).

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.192-200
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• 2002

A modified asymmetric rectangular fin is analysed using the two-dimensional separation of variables method. This modified rectangular fin is made by attaching the wing on the top side of a rectangular fin. Heat loss from each side of this modified rectangular fin is calculated. The relative increasing ratio of heat loss between a modified rectangular fin and a rectangular fin is presented as a function of dimensionless fin volume, wing height and the location of the wing. Especially, to show the remarkable effect of the wing on the heat loss, the relative increasing ratios of heat loss between two different volume increasing methods are listed.