• 수산해양기술연구
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• 제55권4호
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• pp.402-410
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• 2019

This paper deals with the disturbance observer (DOB) based sliding mode control (SMC) for a DC motor to control motor rotating speed precisely and to ensure strong robustness against disturbance including load torque and parameter variation. The reason of steady state error in speed on conventional SMC without DOB is analyzed in detail. Especially, the suggested DOB is designed to prevent measuring noise and harmonics caused by derivative operation on rotating speed. The control performance of the DOB based SMC is evaluated by the various simulations. The simulation results showed that the DOB based SMC had more robust performance than the SMC system without DOB. Especially, precise speed control was possible even though motor parameter variation and load torque was added to the system.

• 한국영어학회지:영어학
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• 제3권4호
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• pp.527-545
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• 2003

I look at the respective responsibilities of different components of the language faculty in the description of two radically different kinds of linguistic phenomenon. The first is the production/perception mismatch in the child's acquisition of the phonology of its first language. There is strong evidence that the child's lexical representations are the same as the adult's, but I argue that the child's own pronunciations, have no linguistic status and are best treated as the product of a neural network. The second is the nature of compositionality, where I argue that compositionality in Natural Language is derivative from that in the Language of Thought. With this assumption and using evidence from quantification in ‘backward control’ structures, I argue that chain theory is intrinsically inimical to a simple view of the legibility relation between LF and LoT.

• 소성∙가공
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• 제11권7호
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• pp.620-627
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• 2002

The purpose of this paper is the development of an automated measurement system for micro spring based on the digital image processing technique. This micro spring can be used in various engineering applications such as filament, load bearing springs, hard disk suspension and many others. Main functionality of the micro spring inspection system is to measure the representative pitch of the micro spring. The derivative operators are used for edge detection in gray level image. Measurement system developed in this paper consisted of new auto feeding mechanism to take advantage of air pressure. In the process of development of the micro spring inspection system based on the image processing and analysis, strong background technology and know-how have been accumulated to measure micro mechanical parts.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1588-1592
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• 2009

Lithium cyanoaluminum hydride (LCAH) was prepared by the metal cation exchange reaction of sodium cyanoaluminum hydride with lithium chloride in tetrahydrofuran. The reducing characteristics of LCAH were explored systematically by the reaction with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0 ${^{\circ}C}$). The reducing ability of LCAH was also compared with of the sodium derivative, sodium cyanoaluminum hydride (SCAH). Generally, the reducing behavior of LCAH resembles that of SCAH closely, but the reactivity of LCAH toward representative organic functional groups appeared to be stronger than that of SCAH. Thus, the regent reduces carbonyl compounds, epoxides, amides, nitriles, disulfides, carboxylic acids and their acyl derivatives to the corresponding alcohols or amines, at a relatively faster rate than that of SCAH. The cyano substitution, a strong election-withdrawing group, diminishes the reducing power of the parent metal aluminum hydrides and hence effects the alteration of their reducing characteristics.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.1001-1003
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• 1994

A series of phosphodiesters of p-nitrophenyl phosphoryl derivatives were synthesized and used as a model substrate for phospholipase D (PLD). The phosphodiester substrates were synthesized from p-nitrophenyl phosphorodichloridate and corresponding alcohols with different chain lengths and polar groups. To measure the activity of PLD, either spectroscopic method for p-nitrophenol or pH-stat titration method was employed. For each substrate, effects of substrate concentration, pH, and $Ca^{2+}$ ion were examined. The kinetic parameters $V_{max}$ for the different substrates were varied depending on the chain lengths or charge of the alcohols. No calcium effect was observed in the hydrolysis of neutral and negatively charged alcohol derivatives, while positively charged choline derivative showed a strong $Ca^{2+}$ ion dependence.

• 대한수학회논문집
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• 제37권2호
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• pp.455-472
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• 2022

For j = 0, 1, 2,…, k - 1; k ≥ 2; and - 1 ≤ B < A ≤ 1, we have introduced the functions classes denoted by ST_[j,k](A, B) and K_[j,k](A, B), respectively, called the generalized (j, k)-symmetric starlike and convex functions. We first proved the sharp bounds on |f(z)| and |f'(z)|. Various radii related problems, such as radius of (j, k)-symmetric starlikeness, convexity, strongly starlikeness and parabolic starlikeness are determined. The quantity |a²₃ - a₅|, which provide the initial bound on Zalcman functional is obtained for the functions in the family ST_[j,k]. Furthermore, the sharp pre-Schwarzian norm is also established for the case when f is a member of K_[j,k](α) for all 0 ≤ α < 1.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권4호
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• pp.185-223
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• 2022

The classical equation of Jonathan Homer Lane and Robert Emden, a nonlinear second-order ordinary differential equation, models the isothermal spherical clouded gases under the influence of the mutual attractive interaction between the gases' molecules. In this paper, the Adomian decomposition method (ADM) is presented to obtain highly accurate and reliable analytical solutions of a class of generalised Lane-Emden equations with strong nonlinearities. The nonlinear term f(y(x)) of the proposed problem is given by the integer powers of a continuous real-valued function h(y(x)), that is, f(y(x)) = h^m(y(x)), for integer m ≥ 0, real x > 0. In the end, numerical comparisons are presented between the analytical results obtained using the ADM and numerical solutions using the eighth-order nested second derivative two-step Runge-Kutta method (NSDTSRKM) to illustrate the reliability, accuracy, effectiveness and convenience of the proposed methods. The special cases h(y) = sin y(x), cos y(x); h(y) = sinh y(x), cosh y(x) are considered explicitly using both methods. Interestingly, in each of these methods, a unified result is presented for an integer power of any continuous real-valued function - compared with the case by case computations for the nonlinear functions f(y). The results presented in this paper are a generalisation of several published results. Several examples are given to illustrate the proposed methods. Tables of expansion coefficients of the series solutions of some special Lane-Emden type equations are presented. Comparisons of the two results indicate that both methods are reliably and accurately efficient in solving a class of singular strongly nonlinear ordinary differential equations.

• 대한화장품학회지
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• 제33권1호
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• pp.23-28
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• 2007

비타민 C는 강력한 환원제로서 멜라닌 색소의 합성을 저해하는 것으로 알려져 있다. 그러나 일반적인 화장품 제형에서는 낮은 안정성과 경피 흡수의 문제점으로 만족할 만한 효과를 나타내지 못한다. 본 연구에서는 안정성이 개선된 비타민 C의 유도체인 ascorbyl glucoside (AsAG)을 유효성분으로 하여 경피흡수를 증가시키고자 하였다. 본 실험에서는 유연하면서도 박막 형태의 배터리를 장착한 패치 화장품을 제조하고 안정성과 경피흡수성을 평가하였다. 피부에 낮은 전류를 증가하는 이온토포레시스를 활용하여 피부에 적용하는 전류의 세기를 증가시키면 물질의 경피흡수는 증가한다. 그러나 전류의 세기를 증가시키면 피부 부작용이 증가하기 때문에 본 연구에서는 한국인의 피부에 맞는 적절한 전류를 선택하여 피부 부작용을 최소화하였다. 이런 결과들을 바탕으로 유연하면서도 가벼운 박막 배터리를 개발하였으며, 2%의 AsAG을 함유한 이온토포레시스 패치의 안전성, 경피흡수정도, 미백효과 등을 검토한 결과 피부에 가하는 최적의 전류는 1.5 V의 배터리를 사용하여 피부 부작용과 경피흡수를 고려하여 평균 0.1 mA이었다. 또한 패치의 임상실험 결과 유의한 수준의 미백효과를 보였으며 피부 자극도도 통상의 화장품 수준을 나타냈다.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.9-15
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• 2004

본 논문에서는 부분공핍(partially-depleted : PD) 영역과 완전공핍(fully-depleted : FD) 영역을 나누는 임계 전면 게이트 전압 V/sub c/의 해석적 표현을 이용해서 PD 영역과 FD 영역의 천이를 정확히 설명하는 해석적 표면전위 모델(analytical surface potential model)을 소개한다. 이 모델은 모든 동작영역(subthreshold에서 strong inversion까지)에서 유효하고 반복 계산 절차 (iteration procedure)인 수치 해석적 방법보다 훨씬 짧은 계산시간이 걸린다. 이 모델에 기초한 charge sheet 모델이 모는 동작영역에 유효한 드레인 전류의 단일 공식을 유도하는데 사용된다. 대부분의 secondary 효과들이 charge sheet 모델에 쉽게 포함되고 그 모델의 결과들은 수치해석 결과와 실험 결과를 비교적 정확히 일치한다. 세 가지의 smoothing 함수가 사용될지 라도 표면전위 미분 값은 연속이다 더욱 중요한 점은 smoothing 함수에 사용된 파라미터들은 공정 파라미터들에 크게 의존하지 않는다.

• 한국식품저장유통학회지
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• 제21권6호
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• pp.838-843
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• 2014

본 연구에서는 근적외 분광법을 이용하여 양념용 채소로 많이 사용되는 파, 마늘, 양파의 건조 불균일성을 관찰하였다. 대류식 온풍건조기에서 건조 위치에 따른 양념채소류의 건조 상태 차이를 조사한 결과, 건조 트레이의 높이나 위치에 따라 바람의 온도와 습도에 차이가 발생하여 건조가 균일하게 되지 않았다. 건조 정도가 다른 양념채소류의 2차 미분 근적외 스펙트럼을 비교한 결과 1,390 nm에서 1,400 nm 부근의 수소결합이 약한 물이 먼저 증발되었고 1,420 nm 부근의 수소결합이 강한 물은 건조 후에도 잔존함을 관찰할 수 있었다. 초분광 NIR 이미징 기법으로 측정한 스펙트럼을 주성분분석함으로써 건조채소의 건조도를 가시적으로 판별할 수 있었다.