• ETRI Journal
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• v.37 no.1
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• pp.32-42
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• 2015

Orthogonal frequency-division multiplexing (OFDM) suffers from spectral nulls of frequency-selective fading channels. Linear precoded (LP-) OFDM is an effective method that guarantees symbol detectability by spreading the frequency-domain symbols over the whole spectrum. This paper proposes a computationally efficient and low-cost implementation for discrete Hartley transform (DHT) precoded OFDM systems. Compared to conventional DHT-OFDM systems, at the transmitter, both the DHT and the inverse discrete Fourier transform are replaced by a one-level butterfly structure that involves only one addition per symbol to generate the time-domain DHT-OFDM signal. At the receiver, only the DHT is required to recover the distorted signal with a single-tap equalizer in contrast to both the DHT and the DFT in the conventional DHT-OFDM. Theoretical analysis of DHT-OFDM with linear equalizers is presented and confirmed by numerical simulation. It is shown that the proposed DHT-OFDM system achieves similar performance when compared to other LP-OFDMs but exhibits a lower implementation complexity and peak-to-average power ratio.

• Clinical and Experimental Reproductive Medicine
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• v.14 no.2
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• pp.138-148
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• 1987

5${\alpha}$-dihydrotestosterone(DHT)과 testosterone(T)은 남성 생식기관의 주 생성 호르몬들로 그 구조가 매우 비슷하여 이들 각 개를 특이하게 측정(specific determination)하는 방법이 개발되지 않고 있다. 본 연구는 고속액체 크로마토그라피(HPLC)를 이용하여 이들을 분리한 후 섬광면역측 정법(Luminescence immunoassay, LIA)으로 정량하는 방법을 개발하여 이들의 응용 가능성을 검토하고져 하였다. DHT와 T의 retention time은 각각 10.3min, 17.6min이었다. DHT-LIA와 T-LIA에 서 다른 스테로이드들과의 교차반응도는 방사면역측정법(RIA)과 대동소이하였다. 정도관리(quality control) 시료의 intra-assay variation은 DHT-LIA가 8.7%, T-LIA가 6.0%의 변이계수를 나타내었고, inter-assay variation의 변이계수는 각각 12.0% 및 15.3%이었다. 실측치(y)와 기대치(x)간의 관계를 보면, DHT-LIA경우는 Y=0.94X+0.9(r=0.989), T-LIA는 Y=1.01X+0.06(r =0.988)로 두 측정치 사이에는 통계적으로 유의한 차이가 없었다. 위의-측정방법을 이용하여 DHT-enanthate와 T-enanthate 처리후 혈청내 DHT 및 T의 농도변화를 조사한 실험결과 LIA와 RIA의 값사이에 유의한 차이가 없었다. 위의 결과로 보아 본 실험에서 개발된 DHT와 T의 섬광면역측정법은 정립되었다고 사려된다.

• Journal of KIISE:Information Networking
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• v.36 no.2
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• pp.80-89
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• 2009

A DHT(Distributed Hash Table) based P2P is a method that compensates disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do fast data search and maintain search efficiency independent of the number of peers. The peers in a DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in a DHT method should send messages more frequently to keep the routing table updated and reduce the failure of requests. However this results in increasing the overall network traffic. In this paper, we propose a method to reduce the update load of a routing table in the existing DHT by updating it in a reactive way. In the proposed reactive method, a routing table is updated only if a data request is coming whereas it is updated periodically in the existing proactive method. We perform experiments using Chord simulator(I3) made by UC Berkely. The experimental results show the performance improvement of the proposed method compared to the existing method.

• Biomolecules & Therapeutics
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• v.22 no.5
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• pp.426-430
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• 2014

Prostate cancer is the most frequently diagnosed cancer. Although prostate tumors respond to androgen ablation therapy at an early stage, they often acquire the potential of androgen-independent growth. Elevated transcriptional activity of androgen receptor (AR) and/or signal transducer and activator of transcription-3 (STAT3) contributes to the proliferation of prostate cancer cells. In the present study, we examined the effect of resveratrol, a phytoalexin present in grapes, on the reporter gene activity of AR and STAT3 in human prostate cancer (LNCaP-FGC) cells stimulated with interleukin-6 (IL-6) and/or dihydrotestosterone (DHT). Our study revealed that resveratrol suppressed the growth of LNCaP-FGC cells in a time- and concentration-dependent manner. Whereas the AR transcriptional activity was induced by treatment with either IL-6 or DHT, the STAT3 transcriptional activity was induced only by treatment with IL-6 but not with DHT. Resveratrol significantly attenuated IL-6-induced STAT3 transcriptional activity, and DHT- or IL-6-induced AR transcriptional activity. Treatment of cells with DHT plus IL-6 significantly increased the AR transcriptional activity as compared to DHT or IL-6 treatment alone and resveratrol markedly diminished DHT plus IL-6-induced AR transcriptional activity. Furthermore, the production of prostate-specific antigen (PSA) was decreased by resveratrol in the DHT-, IL-6- or DHT plus IL-6-treated LNCaP-FGC cells. Taken together, the inhibitory effects of resveratrol on IL-6- and/or DHT-induced AR transcriptional activity in LNCaP prostate cancer cells are partly mediated through the suppression of STAT3 reporter gene activity, suggesting that resveratrol may be a promising therapeutic choice for the treatment of prostate cancer.

• Korean Journal of Food Science and Technology
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• v.52 no.4
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• pp.385-395
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• 2020

This study examined the effect of 3,4-dihydroxytoluene (DHT) on UVB-induced photoaging and determined its molecular mechanisms, using HaCaT human keratinocytes and SKH-1 hairless mice. DHT suppressed UVB-induced matrix metalloproteinase-1 (MMP-1) expression in HaCaT cells. In vivo data from mouse skin supported that DHT decreased UVB-induced wrinkle formation, epidermal thickness, and matrix metalloproteinase-13 (MMP-13) expression. DHT appeared to exert its anti-aging effects by suppressing UVB-induced Raf-1 kinase activity and subsequent attenuation of UVB-induced phosphorylation of MEK, ERK, and p90RSK in HaCaT cells. In vitro and in vivo pull-down assays revealed that DHT bound with Raf-1 in ATP-noncompetitive manner. Overall, DHT appears to anti-photoaging effects in vitro and in vivo through the suppression of Raf-1 kinase activity and may have potential as a treatment for the prevention of skin aging.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.506-509
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• 2007

Peer-to-Peer(P2P) 시스템의 주된 목적은 공유 파일을 효과적으로 관리하며 공유 파일을 저장한 노드의 위치를 보다 효율적으로 검색하는 것이다. 본 논문에서는 Chord 기법을 기반으로 울트라피어 노드들로만 구성된 DHT 링과 그 하부에 또 하나의 서브 DHT 링을 가진 다중 링 구조를 사용하여 기존 DHT 프로토콜에 비해 보다 확장이 용이하며, 보다 효율적인 파일 공유 기법을 제시하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.3
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• pp.239-253
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• 1987

By the extension and the modification of the efficient aigorithms for the DCT-III, the fast algorithms to compute three versions for DCT, four versions of DST, and a DHT are developed. It is shown that the algorithms developed in this paper have simple structures and the numbers of multipication and addition are reduced as comparies with the existing efficient algorithms. The algorithms presentes in this paper indicate the close relationship amng different versions of the DCT and DST as well as a DHT. The formulas to compute the numbers of multiplication and addition of them are derived.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.695-707
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• 2013

DHT(Distributed Hash Table) networks such as Kademlia are vulnerable to the ID mapping attack caused by the voluntary DHT mapping structure where the location of a node is solely determined by itself on the network topology. This causes security problems such as eclipse, DRDoS and botnet C&C on DHT networks. To prevent ID mapping attacks, we propose a non-voluntary DHT mapping scheme and perform analysis on NAT compatibility, attack resistance, and network dynamicity. Analysis results show that our approach may have an equivalent level of attack resistance comparing with other defense mechanisms and overcome their limitations including NAT compatibility and network dynamicity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1947-1954
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• 2009

Service discovery mechanism is a core technique for getting a desired service in MANET(Mobile Ad-Hoc NETwork) environment. However, As feature of MANET, existing mechanisms have some problem that service requester search for trustable service. also it can not support scalability. in this paper, how to reliably support applications such as service discovery on top of MANET. we are firstly finding a trustable service provider and configure DHT(Distributed Hash Table). P2P's DHT can be adopted to service discovery mechanism because P2P and MANET share certain similarities, primarily the fact that both are instances of self-organizing decentralized systems. Especially, Proposed DHT systems used for P2P overlay network can be effective in reducing the communication overhead in service discovery. So proposed mechanism can support for reliably searching required service and scalability. Simulation results show that our mechanism is scalable and outperforms existing service discovery mechanism.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.251-261
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• 2014

In the typical P2P VOD system, it is very important to develop the fast and efficient peer searching scheme since the peers frequently join and leave to/from P2P system. This paper proposes a new peer searching scheme for P2P VOD system based on DHT network environment. The proposed scheme constructs DHT network by managing the peers having close playback starting times and close network locations into a peer all together. The peer information is mapped onto DHT nodes by hashing the key values each of which consists of the starting time and network location of the peer. From the simulation results, the number of messages required to search the partner peers are decreased, and the number of buffer maps exchanging among the peers are also decreased. The proposed scheme can reduce the average network distances among the partner peers. As a result, the proposed scheme makes routing more efficient and it saves the network resources by decreasing communication traffic overhead.