• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.169-174
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• 2008

In this paper, we have presented techniques to reduce the splicing loss between standard single mode fiber and high ${\Delta}$ single mode fiber based on the mode expanding and mode evolution induced by thermal treatment of the fibers. The experimental results show that mechanical splicing loss can be reduced from 2.3 dB to 0.1 dB through proper thermal treatment of the high ${\Delta}$ fiber. Meanwhile, we achieved $0.2{\sim}0.4dB$ of low splicing loss between two fibers by heating the splicing region using electric arcing or an oxygen flame.

• Kyungpook Mathematical Journal
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• v.60 no.4
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• pp.683-710
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• 2020

Let ℕ be the set of nonnegative integers and 𝕬 be a 2-torsion free triangular algebra over a commutative ring ℛ. In the present paper, under some lenient assumptions on 𝕬, it is proved that if Δ = {𝛿_n}_n∈ℕ is a sequence of ℛ-linear mappings 𝛿_n : 𝕬 → 𝕬 satisfying ${\delta}_n([[x,\;y],\;z])\;=\;\displaystyle\sum_{i+j+k=n}\;[[{\delta}_i(x),\;{\delta}_j(y)],\;{\delta}_k(z)]$ for all x, y, z ∈ 𝕬 with xy = 0 (resp. xy = p, where p is a nontrivial idempotent of 𝕬), then for each n ∈ ℕ, 𝛿_n = d_n + 𝜏_n; where d_n : 𝕬 → 𝕬 is ℛ-linear mapping satisfying $d_n(xy)\;=\;\displaystyle\sum_{i+j=n}\;d_i(x)d_j(y)$ for all x, y ∈ 𝕬, i.e. 𝒟 = {d_n}_n∈ℕ is a higher derivation on 𝕬 and 𝜏_n : 𝕬 → Z(𝕬) (where Z(𝕬) is the center of 𝕬) is an ℛ-linear map vanishing at every second commutator [[x, y], z] with xy = 0 (resp. xy = p).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.57-60
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• 2004

This paper presents multibit Sigma-Delta ADC using Leslie-Singh Structure to Improve nonlinearity of feedback loop. 4-bit flash ADC for multibit Quantization in Sigma Delta modulator offers the following advantages such as lower quantization noise, more accurate white-noise level and more stability over single quantization. For the feedback paths consisting of DAC, the DAC element should have a high matching requirement in order to maintain the linearity performance which can be obtained by the modulator with a multibit quantizer. Thus a Sigma-Delta ADC usually adds the dynamic element matching digital circuit within feedback loop. It occurs complexity of Sigma-Delta Circuit and increase of power dissipation. In this paper using the Leslie-Singh Structure for improving nonliearity of ADC. This structure operate at low oversampling ratio but is difficult to achieve high resolution. So in this paper propose improving loop filter for single-bit feedback multi-bit quantization Sigma-Delta ADC. It obtained 94.3dB signal to noise ratio over 615kHz bandwidth, and 62mW power dissipation at a sampling frequency of 19.6MHz. This Sigma Delta ADC is fabricated in 0.25um CMOS technology with 2.5V supply voltage.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.75-86
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• 1998

The purpose of this study is to evaluate the effects of continuing work on VDT(video display terminal), therefore this study examined visual fatigue, unaided visual acuity, refractive error, accommodation and horizontal phoria of 152 subjects who did two hour long VDT work. For the ocular symptoms, the greatest number was tired eyes accounting for 45.71%. In the visual symptoms, blurred vision was the hightest rate of 80.39% and in case of systemic symptoms shoulder pain was 33.33% marked top ranking. The average of near visual acuity decresed almost 10% from 0.47 to 0.42, but refractive error increased about 0.10D to the direction of myopic shift. The amplitude of accommodation decreased approximately 0.72D from 7.46D to 6.74D. Accommodation facility was delayed from 2.27 second to 2.50 second, the amplitude of positive relative accommodation was decreased from 4.76D to 4.16D and the amplitude of negative relative accommodation was decreased from 2.46D to 2.33D. The horizontal phoria shifted to the direction of esophoria from $1.82{\Delta}$ to $3.24{\Delta}$.

• Bulletin of the Korean Mathematical Society
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• v.47 no.4
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• pp.815-823
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• 2010

Let ${\tau}\;{\neq}\;\delta_0$ be either a power bounded radial measure with compact support on the unit disc D with $\tau(D)\;=\;1$ such that there is a $\delta$ > 0 so that ${\mid}\hat{\tau}(s){\mid}\;{\neq}\;1$ for every $s\;{\in}\;\Sigma(\delta)$ \ {0,1}, or just a radial probability measure on D. Here, we provide a decomposition of the set X = {$h\;{\in}\;L^{\infty}(D)\;{\mid}\;lim_{n{\rightarrow}{\infty}}\;h\;*\;\tau^n$ exists}. Let $\tau_1$, ..., $\tau_n$ be measures on D with above mentioned properties. Here, we prove that if $f\;{in}\;L^{\infty}(D^n)$ satisfies an invariant volume mean value property with respect to $\tau_1$, ..., $\tau_n$, then f is n-harmonic.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.347-350
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• 2003

Optimization of the luminance, luminous efficiency, and address voltage margin characteristics has been made on the delta color array PDP with various hexagonal shape subpixels. The optimal subpixel and electrode designs are obtained for the 42-inch high-definition PDP ($1,366{\times}768$) with the fine pixel pitch less than 0.7 mm. The hexagonal delta array structure shows more improved characteristics than that of the normal delta array structure with rectangular shape subpixels.

• Animal Systematics, Evolution and Diversity
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• v.31 no.2
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• pp.95-100
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• 2015

A taxonomic study of the genus Delta de Saussure, 1855 from Vietnam is presented. A total of four species are recorded: D. campaniforme campaniforme (Fabricius, 1775), D. conoideum (Gmelin, 1790), D. esuriens esuriens (Fabricius, 1787), and D. pyriforme pyriforme (Fabricius, 1775). Of these, D. campaniforme campaniforme was first recorded from Vietnam by de Saussure et al., 1904, under the name Eumenes esuriens and is now reconfirmed to occur in Vietnam after more than 100 years, and D. conoideum is newly recorded from Vietnam. A key to species based on morphological characters is given with illustrations, and distributional records in Vietnam are also provided.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.26-32
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• 2017

This paper presents a low power and high resolution incremental delta-sigma ADC that utilizes a passive integrator instead of an opamp-based active integrator. Opamp is a power-hungry block that involves tight design tradeoffs. To avoid the use of active integrator, the s-domain characteristic of an active integrator is first analyzed. Based on the analysis, an active integrator with low gain design is proposed as an alternative design method. To save power even more aggressively, a passive integrator with no static current is proposed. A 1st order single-bit incremental delta-sigma ADC using the proposed passive integrator is implemented in a 65nm CMOS process. Transistor-level simulation shows that the ADC consumes only 0.6uW under 1.2V supply while achieving SNDR of 71dB with 22kHz bandwidth. The estimated total power consumption including digital filter is 6.25uW, and resulting power efficiency is on a par with state-of-the-art A/D converters.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.294-300
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• 2008

The stable isotopes ratios ($\delta^{13}C\;and\;\delta^{15}N$) of two coexisting species of zooplankton (Daphnia longispina and Acanthodiaptomus pacificus) and POM were determined in two alpine lakes in Japan. The difference of $\delta^{13}C$ between A. pacificus and D. longispina was 4.1$\pm$0.9‰ in Lake Shirakoma, which was larger than in Lake Panke. Whereas the difference of $\delta^{15}N$ between A. pacificus and D. longispina (2.6$\pm$0.8‰) was larger in Lake Panke than in Lake Shirakoma. $\delta^{13}C$ of POM (-26.6$\pm$1.2‰) in Lake Shirakoma was different from those of zooplankton; it was heavier than those of D. longispina and A. pacificus by 3.7$\pm$1.6‰ and 7.8$\pm$1.0‰, respectively. Whereas $\delta^{15}N$ of POM (2.0$\pm$0.8‰) was similar with those of both A. pacificus and D. longispina. This implies that the two lakes may have different trophic structure and food sources for zooplankton, and each species are grazing on selectively different components of POM. The temporal variation of $\delta^{13}C$ for each zooplankton species was associated with lipid contents of zooplankton in both lakes. The results showed that stable isotope composition of zooplankton can be an useful information for understanding energy pathways and trophic structures in lakes.

• Journal of applied mathematics & informatics
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• v.24 no.1_2
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• pp.357-366
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• 2007

Let G(V, E) be a simple graph, and let f be an integer function on V with $1{\leq}f(v){\leq}d(v)$ to each vertex $v{\in}V$. An f-edge cover-coloring of a graph G is a coloring of edge set E such that each color appears at each vertex $v{\in}V$ at least f(v) times. The f-edge cover chromatic index of G, denoted by ${\chi}'_{fc}(G)$, is the maximum number of colors such that an f-edge cover-coloring of G exists. Any simple graph G has an f-edge cover chromatic index equal to ${\delta}_f\;or\;{\delta}_f-1,\;where\;{\delta}_f{=}^{min}_{v{\in}V}\{\lfloor\frac{d(v)}{f(v)}\rfloor\}$. Let G be a connected and not complete graph with ${\chi}'_{fc}(G)={\delta}_f-1$, if for each $u,\;v{\in}V\;and\;e=uv{\nin}E$, we have ${\chi}'_{fc}(G+e)>{\chi}'_{fc}(G)$, then G is called an f-edge covered critical graph. In this paper, some properties on f-edge covered critical graph are discussed. It is proved that if G is an f-edge covered critical graph, then for each $u,\;v{\in}V\;and\;e=uv{\nin}E$ there exists $w{\in}\{u,v\}\;with\;d(w)\leq{\delta}_f(f(w)+1)-2$ such that w is adjacent to at least $d(w)-{\delta}_f+1$ vertices which are all ${\delta}_f-vertex$ in G.