• Journal of the Korean Mathematical Society
• /
• v.33 no.2
• /
• pp.235-247
• /
• 1996

Many numerical computations in science and engineering can only be solved approximately since the available infomation is partial. For instance, for problems defined ona space of functions, information about f is typically provided by few function values, $N(f) = [f(x_1), f(x_2), \ldots, f(x_n)]$. Knwing N(f), the solution is approximated by a numerical method. The error between the true and the approximate solutions can be reduced by acquiring more information. However, this increases the cost. Hence there is a trade-off between the error and the cost.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.2 no.1
• /
• pp.19-29
• /
• 1999

This paper treats the implementation of concurrent engineering principles for ROC development of a future infantry fighting vehicle. Based on the acquisition process of weapon systems and operational requirements provided by users, Quality Function Deployment(QFD) is used to translate the requirements of the user into specific trade-off analysis. Results of these studies and the use of concurrent engineering principles are presented.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10a
• /
• pp.471-473
• /
• 2000

소프트웨어의 대형화, 복잡화에 따라 아키텍처의 중요성이 더욱 강조되고 있다. 또한, 복잡한 사용자의 요구사항을 소프트웨어에 혹은 아키텍처에 잘 반영시킬 수 있는 방안이 연구되어지고 있다. 이 논문에서는 주요한 소프트웨어 아키텍처 분석, 검증 방법들 중의 하나인 ATAM을 지원하는 도구로서 WSMS를 제안하고 있다. WSMS는 웹 기반의 시나리오 관리도구로서, ATAM에서 아키텍처의 다양한 면을 기술하는 시나리오의 효율적인 관리를 위해 시나리오의 추출, 분류, 우선순위 결정, 변경관리 등의 기능을 수행한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.242-245
• /
• 2001

본 논문은 디지털 위성용 하향변환기에 적용되는 고안정 전압제어 마이크로파 발진기의 위상잡음 특성을 분석하였다. 전압제어 마이크로파 발진기는 능동소자의 비선형 등가모델과 궤환회로의 영향을 고려하여 유전체 공진 마이크로파 발진기를 위상잡음과 출력 전력에 절충(trade-off)하여 설계하였고, 13.25GHz의 발진주파수에서 출력이득은 12dBm이고, 위상잡음은 옵셋 주파수 100KHz 에서 -107.91dBc를 보였다. 바렉터 다이오드 동작에 의한 튜닝 범위는 2MHz/V로 위상동기 발진기에 응용할 수 있음을 보였다.

• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.805-810
• /
• 2019

We present a time-frequency analysis algorithm based on the multitaper method and the state-space frameworks. In general, time-frequency representations have a trade-off between the time duration and the spectral bandwidth by the uncertainty principle. To optimize the trade-off problems, the short-time Fourier transform and wavelet based algorithms have been developed. Alternatively, the authors proposed the state-space frameworks based on the multitaper method in the previous work. In this paper, we develop a real-time algorithm to estimate variances and spectrum using the state-space framework. We test our algorithm in spectral analysis of simulated data.

• Journal of the Korean Ceramic Society
• /
• v.39 no.8
• /
• pp.721-727
• /
• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Journal of Korean Society of Steel Construction
• /
• v.19 no.1
• /
• pp.15-27
• /
• 2007

Over the past decade, labor costs have increased relative to the cost of material hardware according to analysts in the construction industry. Therefore, the minimum weight design, which has been widely adopted in the literature for the optimal design of steel structures, is no longer the most economical construction approach. Presently, although connection- related costs is crucial in determining the most cost-effective steel structures, most studies on this subject focused on minimum-weight design or engaged in higher analysis. Therefore, in this study, we proposed a fabrication scheme for the most cost-effective moment-resisting steel frame structures that resist lateral loads without compromising overall stability. The proposed approach considers the cost of steel products, fabrication, and connections within the design process. The optimal design considered construction realities, with the optimal trade-off between the number of moment connections and total cost was achieved by reducing the number of moment connections and rearranging them using the combination of analysis that includes shear, displacement and interaction value based on the LRFD code and optimization scheme based on genetic algorithms. In this study, we have shown the applicability and efficiency in the examples that considered actual loading conditions.

• Health Policy and Management
• /
• v.17 no.4
• /
• pp.113-133
• /
• 2007

The present study was conducted to measure health-related utility for post-menopausal symptoms among Korean woman. A survey questionnaire was developed to measure utility based on visual analogue scale(VAS) and time trade-off method (TTO). From January 29 to February 3, 2007, a face-to-face interview was conducted with 274 women aged 45 to 60 to ask about their subjective utility for hypothetical health status of mild or severe post-menopausal symptoms. Among the participants, 160 were recruited from outpatient departments of 3 hospitals and 114 from 2 sports centers located in Seoul. For mild symptom, the average utility score of the respondents was $0.63{\pm}0.14$ based on VAS and $0.61{\pm}0.26$ based on ITO. For severe symptoms, the average utility was $0.39{\pm}0.16$(VAS) and $0.44{\pm}0.27$ (TTO). For severe symptom, a higher utility score was observed for TTO than for VAS, which is consistent with earlier studies and thus supports the validity of the utility measurement in this study. Overall, the severity of post-menopausal symptoms of the respondents themselves was not significantly associated with the utility score that the respondents answered for hypothetical health status. Multiple regression analysis results showed that the utility score was significantly higher among respondents with older age, higher education, higher family income, and from hospitals. It is expected that the utility score measured in this study will enhance the understanding of the quality of life of women after menopause and will be used to conduct cost-utility analysis of health care interventions to treat post-menopausal symptoms.

• Journal of the Korean Society of Systems Engineering
• /
• v.1 no.2
• /
• pp.69-76
• /
• 2005

Defense analysis & evaluation includes menace analysis, validation analysis, problem analysis, scientific technical analysis, technical trade-off analysis, alternative analysis, cost analysis, etc. Reliable related data is required to perform these analysis activities efficiently. but in case of these defense analysis & evaluation data acquisition system, the data is insufficient and scattered about each organization. The data of database system is also not utilized sufficiently. Abroad technical data is also low level data such as catalog or military officer's collection. Therefore, this paper propose defense analysis & evaluation data acquisition system by systems engineering process. we also propose construction method of data acquisition system.

• Korean Journal of Community Nutrition
• /
• v.7 no.3
• /
• pp.354-360
• /
• 2002

The purposes of this study were (1) to understand how customers trade off one attribute against another when they choose a pizza restaurant, (2) to compare the importance of individual attributes with their relative importance and (3) to compare customers'brand choice patterns with the prediction of pizza restaurant operators. Empirical data for this study were collected from the customers (n=307) and operators (n=273) of flour famous pizza franchise restaurants in Korea, Pizza Hut, Mister Pizza, Domino's Pizza and Pizza Mall. The attributes and attribute levels for the hypothetical profiles were decided from the focus group discussion. A total of 16 profiles was selected from fractional factorial designs. The SPSS conjoint procedure was used to calculate utility scores and simulate profiles. The overall group statistics showed the relative importance of all attributes compared with one other. Taste was the most important attribute (32.48%) in choosing a pizza restaurant, followed by service (21.87%) , atmosphere (17.23%), price (15.17%) and speed of delivery (13.26%). There was a difference between the customers'ratings of the importance of the individual attributes and the ranking of the same attributes'relative importance as derived from the conjoint analysis. The operators rated service (26.54%) as also being important, as well as taste (27.76%), in choosing a pizza restaurant. The rankings of relative importance for pizza taste, service and price were statistically different in the customers'and operators'data (p < 0.001, p < 0.1, p < 0.5). Operators who want to differentiate themselves from their competitors should make decisions based on an increased understanding of their customers'brand choice decision process and measure the hidden needs of their customers.