• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.363-367
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• 2009

An isotope-dilution flow-injection electrospray/mass spectrometric method was developed for the accurate determination of glucosamine contents in pharmaceutical formulations. Samples were extracted by methanol. After spiking glucosamine-1-$^{13}C_1$ as an internal standard, the extracts were then analyzed by flow-injection ESI/MS in a selected ion monitoring (SIM) mode to detect [M+H]$^+$ ions of the analyte and its isotope analogue at m/z 180 and m/z 181, respectively. Confirmatory measurements were made by selectively monitoring the collisionally induced dissociation channels of m/z 180 $\rightarrow$ m/z 72 and m/z 181 $\rightarrow$73, respectively, to test the possibility of bias in the SIM method due to matrix interferences, but any significant bias in the SIM mode was not observed. Repeatability and reproducibility studies showed that the flow-injection ESI/MS method is a reliable and reproducible method which can provide a typical method precision of 1.0 %. Other results for the method validation are reported.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.551-554
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• 2002

The paper discusses new approach for machining operation simulation using enhanced Z map algorithm. To extract the required geometric information from NC code, suggested algorithm uses supersampling method to enhance the efficiency of a simulation process. By executing redundant Boolean operations in a grid cell and averaging down calculated data, presented algorithm can accurately represent material removal volume though tool swept volume is negligibly small. Supersampling method is the most common form of antialiasing and usually used with polygon mesh rendering in computer graphics. The key advantage of enhanced Z map model is that the data structure is same with conventional Z map model, though it can acquire higher accuracy and reliability with same or lower computation time. By simulating machining operation efficiently, this system can be used to improve the reliability and efficiency of NC machining process as well as the quality of the final product.

• 정보교육학회논문지
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• 제8권4호
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• pp.555-562
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• 2004

소프트웨어 명세는 비정형, 반 정형, 정형 기법이 존재한다. 이 중 정형 기법은 수학적인 이론을 바탕으로 명세의 모호성, 애매성, 불완전성을 제거하는데 효율적으로 사용되어 왔다. 본 논문에서는 Z 정형명세로부터 EJB의 자바 소스코드 까지의 구현 단계를 제안하였다. 또한, 사례 연구로 Stack을 명세하고 EJB 컴포넌트를 구현하는 단계를 제시하였다. 결론적으로 Z의 명세는 스키마의 분류, 인터페이스의 정의, Post-condition과 Pre-condition의 정의 단계를 거치고 정제를 통해서 EBJ의 인터페이스, 예외 클래스, 메소드 구현에 사용할 수 있음을 보였다.

• 한국광학회지
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• 제7권1호
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• pp.77-86
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• 1996

$Ti:LiNbO_3$ Mach-Zehnder 진행파형 광변조기의 CPW(coplanar waveguide) 전극구조, 특히 taper영역을 해석하기 위해서 SOR(successive over relaxation)법을 이용하였다. 변조기의 taper영역에서는 임피던스 정합, 즉 $Z_c 가 50\omega$이 만족되는 전극구조를 설계하였다. 변조기의 변조영역에서는 $Z_c=50\omega, n$$Z_c$ c/=50.OMEGA., n=2.26인 설계파라미터와, n$_{eff}$=2.2, Z$_{c}$=47.7.OMEGA.인 설계파라미터를 찾았다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제12권2호
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• pp.141-148
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• 2006

본 논문에서는 정형 검증 도구를 이용한 보안 소프트웨어의 보안성을 검증하고 검증된 결과를 이용하여 안전한 보안 소프트웨어 개발 방안을 살펴본다. 정형 검증 기법에 따라 사용되어질 수 있는 각 정형 검증 도구들을 살펴보고 그 특성을 파악하여 보안 소프트웨어의 안정성과 신뢰성을 보장하는 적합한 도구들을 알아보고, 보안 소프트웨어 개발 방안을 제시한다. Z 언어를 이용하는 도구인 Z/EVES는 Z명세에 대한 분석 방법을 제시함으로써 보안 소프트웨어에서 가장 많이 사용되는 대표적인 정형 검증 도구이다. 본 논문에서는 보안 소프트웨어 검증을 위하여 C 언어로 작성된 보안 소프트웨어를 Z명세 언어로 변환하고 이것을 Z/EVES도구를 이용한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.39-41
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• 1996

While the z-transform method is a basic mathematical tool to relate the signals only at the sampling instants in analyzing and designing sampled-data control systems, the modified z-transform which is a variation of the z-transform is widely used to represent the details of continuous signals between the sampling instants. Regarding the modified z-transform method, some properties were established to relate the modified z-transform to the regular z-transform. This paper will show that these properties, in their current forms, cause some analytic problems, when they are applied to the signals with discontinuities at the sampling instants, which accordingly limit their applications significantly. In this paper, those analytic problems will be investigated, and the theorems of the modified z-transform will be revised by adopting a new notation so that those can be correctly interpreted and used without any analytic problems in the analysis of sampled data systems. Also some useful schemes of applying the modified z-transform will be developed.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.41-48
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• 2008

본 연구에서는 전압품질에 민감한 설비를 위한 3상 Z-소스 동적 전압 보상기(Z-DVR : Z-Source Dynamic Voltage Restorer)를 제시하였다. 제안된 시스템은 수동필터와 Z-소스 토폴로지의 직렬형 능동필터로 구성된다. Z-DVR의 ESS(Energy Storage System)로는 친환경적인 고분자 전해질 연료전지(PEMFC : Proton Exchange Membrane Fuel Cells)를 사용하였다. 고조파 검출은 동기좌표계의 $i_{d}-i_{q}$ 이론에 의하였으며, 부하전압 보상을 위하여 PI제어를 사용하였다. 3상 전원이 모두 전압 sag가 발생하는 경우, PSIM에 의하여 제안된 방법과 배터리 스택을 적용하는 종전의 방법에 대하여 시뮬레이션을 수행하였으며, 전압 보상성능이 유사함을 알 수 있었다. 또한 전압 sag와 swell이 동시에 또는 독립적으로 발생하는 다양한 전원 조건하에서 제안된 시스템의 전압 보상 성능과 전압에 대한 %THD(%Total Harmonic Distortion)를 검토하였다.

• 전력전자학회논문지
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• 제18권2호
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• pp.123-130
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• 2013

This paper proposes the switched trans Z-source inverter(STZSI) which combined the characteristics of the trans Z-source inverter(TZSI) and the switched inductor Z-source inverter(SLZSI). The proposed STZSI has the same performance compared with the SLZSI which is improved the voltage boost performance of the conventional typical X-shaped ZSI, and it has advantage that circuit structure of Z-impedance network is more simple. And, in order to step up the voltage boost factor under the condition of the same duty ratio, unlike the SLZSI adding the inductors and diodes, the proposed method is dune by changing the turn ratio of trans primary winding of Z-impedance network. To confirm the validity of the proposed method, PSIM simulation and a DSP(TMS320F28335) based experiment were performed using trans with turn ratio 1 and 2 under the condition of the input DC voltage VI=50V, duty ratio D=0.1 and D=0.15. As a result, under the same input/ouput condition, the inverter arm voltage stress of the proposed method is reduced to about 15%-22% as compared with typical X-shaped ZSI, and the elements in Z-impedance network of the proposed method is reduced as compared with the SLZSI.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제19권1호
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• pp.59-71
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• 2012

In this paper, we prove the stability in random normed spaces via fixed point method for the functional equation $$f(x+y+z)-f(x+y)-f(y+z)-f(x+z)+f(x)+f(y)+f(z)=0$$. by using a fixed point theorem in the sense of L. C$\breve{a}$dariu and V. Radu.

• 한국CDE학회논문집
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• 제7권4호
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• pp.219-232
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• 2002

In numerically controlled(NC) machining simulation, a Z-map has been used frequently for representing a workpiece. Since the Z-map is usually represented by a set of Z-axis aligned vectors, the machining process can be simulated through calculating the intersection points between the vectors and the surface swept by a machining tool. In this paper, we present an efficient method to calculate those intersection points when an APT-type tool moves along a linear tool path. Each of the intersection points can be expressed as the solution of a system of non-linear equations. We transform this system of equations into a single-variable equation, and calculate the candidate interval in which the unique solution exists. We prove the existence of a solution and its uniqueness in this candidate interval. Based on these characteristics, we can effectively apply numerical methods to finally calculate the solution of the non-linear equations within a given precision. The whole process of NC simulation can be achieved by updating the Z-map properly. Our method can provide more accurate results with a little more processing time, in comparison with the previous closed-form solution.