• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5209-5228
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• 2016

Device-to-device (D2D) communication underlaying cellular networks can bring significate benefits for improving the performance of mobile services. However, it hinges on elaborate resource sharing scheme to coordinate interference between cellular users and D2D pairs. We formulate a joint mode selection, link allocation and power control optimization problem for D2D communication sharing uplink resources in a multi-user cellular network and consider the efficiency and the fairness simultaneously. Due to the non-convex difficulty, we propose a three-step scheme: firstly, we conduct mode selection for D2D pairs based on a minimum distance metric after an admission control and obtain some cellular candidates for them. And then, a cellular candidate will be paired to each D2D pair based on fairness. Finally, we use Lagrangian Algorithm to formulate a joint power control strategy for D2D pairs and their reused cellular users and a closed-form of solution is derived. Simulation results demonstrate that our proposed algorithms converge in a short time. Moreover, both the sum rate of D2D pairs and the energy efficiency of cellular users are improved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1884-1903
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• 2019

Device-to-Device (D2D) communications can provide proximity based services in the future 5G cellular networks. It allows short range communication in a limited area with the advantages of power saving, high data rate and traffic offloading. However, D2D communications may reuse the licensed channels with cellular communications and potentially result in critical interferences to nearby devices. To control the interference and improve network throughput in overlaid D2D cellular networks, a novel channel assignment approach is proposed in this paper. First, we characterize the performance of devices by using Poisson point process model. Then, we convert the throughput maximization problem into an optimal spectrum allocation problem with signal to interference plus noise ratio constraints and solve it, i.e., assigning appropriate fractions of channels to cellular communications and D2D communications. In order to mitigate the interferences between D2D devices, a cluster-based multi-channel assignment algorithm is proposed. The algorithm first cluster D2D communications into clusters to reduce the problem scale. After that, a multi-channel assignment algorithm is proposed to mitigate critical interferences among nearby devices for each D2D cluster individually. The simulation analysis conforms that the proposed algorithm can greatly increase system throughput.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.16-33
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• 2019

In this paper, a full-duplex NOMA relaying based underlay device-to-device (D2D) communication scheme is proposed, in which D2D transmitter assists cellular downlink transmission as a full-duplex relay. Specifically, D2D transmitter receives signals from base station and transmits the superposition signals to D2D receiver and cellular user in NOMA scheme simultaneously. Furthermore, we investigate the power allocation under the proposed scheme, aiming to maximize D2D link's achievable transmit rate under cellular link's transmit rate constraint and total power constraint. To tackle the power allocation problem, we first propose a power allocation method based on linear fractional programming. In addition, we derive closed-form expressions of the optimal transmit power for base station and D2D transmitter. Simulation results show that the performance of two solutions matches well and the proposed full-duplex NOMA relaying based underlay D2D communication scheme outperforms existing full-duplex relaying based D2D communication scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2240-2254
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• 2021

We investigate the channel allocation problem in an ultra-dense device-to-device (D2D) enabled cellular network in underlaying mode where multiple D2D users are forced to share the same channel. Two kinds of low complexity solutions, which just require partial channel state information (CSI) exchange, are devised to resolve the combinatorial optimization problem with the quality of service (QoS) guaranteeing. We begin by sorting the cellular users equipment (CUEs) links in sequence in a matric of interference tolerance for ensuring the SINR requirement. Moreover, the interference quota of CUEs is regarded as one kind of communication resource. Multiple D2D candidates compete for the interference quota to establish spectrum sharing links. Then base station calculates the occupation of interference quota by D2D users with partial CSI such as the interference channel gain of D2D users and the channel gain of D2D themselves, and carries out the channel allocation by setting different access priorities distribution. In this paper, we proposed two novel fast matching algorithms utilize partial information rather than global CSI exchanging, which reduce the computation complexity. Numerical results reveal that, our proposed algorithms achieve outstanding performance than the contrast algorithms including Hungarian algorithm in terms of throughput, fairness and access rate. Specifically, the performance of our proposed channel allocation algorithm is more superior in ultra-dense D2D scenarios.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.479-486
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• 2016

In this paper, the algorithm which can convert a 2D image into a 3D Model will be discussed. The 2D picture drawn by a user is scanned for image processing. The Canny algorithm is employed to find the contour. The waterfront algorithm is proposed to find foreground image area. The foreground area is segmented to decompose the complex shapes into simple shapes. Then, simple segmented foreground image is converted into 3D model to become a complex 3D model. The 3D conversion formular used in this paper is also discussed. The generated 3D model data will be useful for 3D animation and other 3D contents creation.

• 대한수학회보
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• 제34권4호
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• pp.595-601
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• 1997

Let $C_d$ be the rational curve of degree d in $P_k ^3$ given parametrically by $x_0 = u^d, X_1 = u^{d - 1}t, X_2 = ut^{d - 1}, X_3 = t^d (d \geq 4)$. Then the defining ideal of $C_d$ can be minimally generated by d polynomials $F_1, F_2, \ldots, F_d$ such that $degF_1 = 2, degF_2 = \cdots = degF_d = d - 1$ and $C_d$ is a set-theoretically complete intersection on $F_2 = X_1^{d-1} - X_2X_0^{d-2}$ for every field k of characteristic p > 0. For the proofs we will use the notion of Grobner basis.

• 생약학회지
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• 제30권2호
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• pp.168-172
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• 1999

Five compounds were isolated from the roots of Polygala tenuifolia (Polygalaceae). On the basis of spectroscopic evidences, the structures of these compounds were characterized as ${\alpha}-D-(6-O-sinapoyl)-glucopyranosyl(1{\rightarrow}2')-{\beta}-D-(3'-O-sinapoyl)-fructofuranoside$ (P3), ${\alpha}$-D-{6-O-(p-methoxybenzoyl)}-glucopyranosyl-$(1{\rightarrow}2')$-${\beta}$-D-{3'-O-(3',4',5'-trimethoxycinnamoyl)}-fructofuranoside(P4), ${\alpha}$-D-{6-O-(p-hydroxybenzoyl)}-glucopyranosyl-$(1{\rightarrow}2')$-${\beta}$-D-{3'-O-(3',4',5'-trimethoxycinnamoyl)}-fructofuranoside(P5), ${\alpha}-D-glucopyranosyl-(1{\rightarrow}2')-{\beta}-D-(1'-O-sinapoyl)-fructofuranoside$(P6), $1,5-anhydro-D-glucitol$(P7) respectively. ${\alpha}$-D-{6-O-(p-Methoxybenzoyl)}-glucopyranosyl-$(1{\rightarrow}2')$-${\beta}$-D-{3'-O-(3',4',5'-trimethoxycinnamoyl)}-fructofuranoside(P4) and ${\alpha}-D-glucopyranosyl-(1{\rightarrow}2')-{\beta}-D-(1'-O-sinapoyl)-fructofuranoside$(P6) were isolated for the first time from the genus of Polygala. 1,5-Anhydro-D-glucitol(P7) was isolated without hydrolysis for the first time from the root of Polygala tenuifolia.

• 한국안광학회지
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• 제18권2호
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• pp.157-163
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• 2013

목적: 본 연구는 근거리에서의 2D와 3D 영상시청이 조절기능에 미치는 영향과 2D와 3D차이를 알아보고자 하였다. 방법: 3D 입체영상 시청이 가능한 20~40대($22.9{\pm}3.93$세)의 50명(남 30명, 여 20명)을 대상으로 실시하였다. 영상시청 전과 2D와 3D 영상을 각각 1 m 거리에서 30분 동안 시청한 후에 조절근점(NPA)으로 구한 조절력(AA), 조절반응(AR), 양 음성상대조절력(PRA, NRA), 조절용이성(AF)을 각각 검사하였다. 결과: 조절력은 영상시청 전과 비교하여 2D와 3D 시청 후에 모두 감소하였으며, 3D 영상시청 직후가 2D 영상시청 직후 보다 더 많은 감소를 보였다. 조절반응은 시청 전과 비교하여 2D와 3D 영상 시청 후 모두에서 증가하였지만 2D와 3D 영상시청 간의 차이는 없었다. 상대조절력 검사에서 PRA와 NRA 모두 유의한 변화는 없었다. 조절용이에 의한 조절 속도는 영상시청 전($13.52{\pm}3.32$ cpm)과 2D 영상시청 직후($14.28{\pm}3.21$ cpm), 3D 영상시청 직후($14.90{\pm}3.27$ cpm) 순으로 증가하는 것으로 나타났다. 결론: 근거리 영상 시청이 조절기능에 영향을 주었으며 영상 시청 전, 2D 영상시청 후, 3D영상시청 후의 순서의 조절력 감소는 안정피로에 동일한 순서로 영향을 미칠 수 있다. 특히 3D 영상시청 후 조절용이성의 증가는 시기능훈련(VT)의 가능성을 보이고, 앞으로 3D 영상을 이용한 구체적인 VT 연구도 요구된다.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.854-860
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• 2017

본 연구에서는 di-(2-ethylhexyl)-phosphoric acid (D2EHPA)와 carbon nanotubes (CNTs)를 polysulfone (PSf)에 고정화시켜 PSf/D2EHPA/CNTs 비드를 제조하였으며, 제조한 비드에 의한 Sr(II)의 제거특성을 살펴보았다. Scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FTIR) 및 Thermo gravimetric analysis (TGA) 분석을 통하여 PSf/D2EHPA/CNTs 비드의 형태적 특성들을 조사하였다. PSf/D2EHPA/CNTs 비드에 의한 Sr(II)의 제거는 운전시간 60 min 정도에서 평형에 도달하였으며, 속도 실험결과는 유사 2차 속도식에 잘 부합하는 것으로 나타났다. 또한 PSf/D2EHPA/CNTs 비드에 의한 Sr(II)의 제거에서 Langmuir 식으로부터 구한 최대 제거량은 4.75 mg/g이었다. PSf/D2EHPA/CNTs 비드에 의한 Sr(II)의 제거효율은 추출제 D2EHPA 만을 사용하는 경우보다 CNTs를 첨가함으로써 Sr(II)의 제거량이 2.5배 정도 향상되는 결과를 보였다.

• 대한수학회보
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• 제56권3호
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• pp.649-658
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• 2019

In this paper, we prove some congruences involving the generalized Catalan numbers and harmonic numbers modulo $p^2$, one of which is $$\sum\limits_{k=1}^{p-1}k^2B_{p,k}B_{p,k-d}{\equiv}4(-1)^d\{{\frac{1}{3}}d(2d^2+1)(4pH_d-1)-p\({\frac{26}{9}}d^3+{\frac{4}{3}}d^2+{\frac{7}{9}}d+{\frac{1}{2}}\)\}\;(mod\;p^2)$$, where a prime number p > 3 and $1{\leq}d{\leq}p$.