• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.3
• /
• pp.255-266
• /
• 2009

In this study, a robust aerospace system design process for the aerospace system is developed by considering the uncertainties of user requirements, manufacturing errors, and operational environment variation. User requirements are analyzed and quantified by decision making models and system engineering methods to select alternative concepts which satisfies the various requirements. Robust design and optimization method is applied to derive the robust solution of the selected system. First, a variance of objective function is calculated, and a mean value and a variance of target value are determined by the deterministic design optimization results of the system. A robust optimum design formulation is then needed to derive the robust solution that minimizes the variance of the response and moves the mean values to the target value. It is applied to Very Light Jet (VLJ) aircraft to which much attention is paid recently in civil aerospace market.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.51-51
• /
• 2017

지역빈도해석은 짧은 기간의 자료를 보유하고 있는 계측 지점이나 자료가 없는 미계측 지점에서의 확률수문량을 산정하기 위하여 많이 쓰여 진다. 지역빈도해석을 실시하기 위한 조건으로는 우선 수집된 하천유역들을 대상으로 수문학적 동질 지역을 구분하는 것이 중요하다. 그리고 구분되어진 지역에 포함되는 모든 지점들의 자료를 빈도해석 함으로써 관심 지점의 신뢰할 만한 확률수문량을 산정하는 것이다. 그동안의 지역빈도해석은 주로 비건조지역을 중심으로 홍수와 같은 재난재해 대비 그리고 수자원 관리를 위한 연구들을 실시해왔다. 본 연구의 주 목적은 건조지역의 수자원 관리를 위해 건조지역 하천유역을 중심으로 지역빈도해석을 실시하여 신뢰할만한 확률수문량을 산정하는 것이다. 확률수문량 산정값의 정확도를 향상시키기 위해 지역빈도해석 모델에 쓰여 지는 새로운 지형학적 변수들을 제공하였고 수문학적 동질 지역을 구분 위해 수집된 각 하천유역의 형상들을 확인하여 동질 지역을 정의하였다. 예를 들면, 수지형 유역, 부채형 유역, 격자형 유역과 같은 다른 형상들을 구분하여 각 유역 형상 종류별로 동질 지역을 만들었다. 건조지역의 지역빈도해석을 위해 미국 건조지역의 105개 하천유역 유량자료들을 수집 및 이용하였다. 확률수문량 산정을 위하여 앙상블 인경신경망 (Ensemble Artificial Neural Network)과 정준 상관 계수(Canonical Correlation Analysis)를 이용한 지역빈도해석 모델을 만들었다. 제안된 모델의 수행평가와 정확성 평가를 위해 리샘플링 기법인 10-겹 교차 검증 (10-fold cross-validation), 잭나이프 (Jackknife) 기법들을 이용하였고 모델로부터 산정된 확률수문량값을 편향 (Bias), 상대 편향(rBias), 평균 제곱근 오차 (RMSE), 상대 평균 제곱근 오차 (rRMSE)를 통하여 산정 값과 실제 관측 값의 차이를 분석하였다. 그 결과 건조지역의 지역빈도해석을 위해 새롭게 제시된 지형학적 변수들을 사용하였을 때 모델의 수행능력이 향상되었음을 확인하였다. 또한 하천유역 형상에 따라 동질 지역을 구분하였을 때 향상된 확률수문량이 산정되었다. 향상된 지역빈도해석 모델을 통해 건조지역의 신뢰할만한 확률수문량을 산정함으로써 건조지역의 효과적인 수자원 관리를 위한 수공시설물 설계에 중요한 정보들을 제공할 것이다.

• Food Engineering Progress
• /
• v.15 no.4
• /
• pp.297-304
• /
• 2011

Ramen flour formulation was optimized by applying a mixture experimental design. In the optimization, the overall palatability (OP) of cooked ramen and the rheological properties of selected dough were maximized or minimized. Blended ratios of the ingredients such as Dark Northern Spring (DNS), Hard Red Winter (HRW), and Soft White (SW) were designed on a simplex-lattice. Dough rheological properties were measured by Rapid Visco Analyser (RVA), Farinograph, and Extensograph, and the overall palatability by sensory evaluation. Several principal dough rheological properties such as RVA peak viscosity (PV), Farinograph development time (DT), and Extensograph resistance/extensibility after 45 min (R/E 45 min) were selected to influence the overall palatability by canonical correlation analysis (CCA). Goals of the optimization were given as OP maximized, PV maximized, DT minimized, and R/E at 45 min maximized. The optimization results were found to be DNS 33.3%, HRW 33.3%, and SW 33.3% with OP, 5.825; PV, 587.9 cP; DT, 3.1 min; R/E at 45 min, 2.339 BU/mm.

• Culinary science and hospitality research
• /
• v.19 no.3
• /
• pp.194-208
• /
• 2013

This study presented a theoretical research system about the impact of boss' transformational leadership that is recognized by super luxury hotel chefs on their job satisfaction and performance, and on the basis of this theoretical background, the model was derived and the hypothesis was confirmed by empirical research. A frequency analysis was conducted to determine the general characteristics of the 245 samples collected in this study, an exploratory factor analysis for the verification of the validity of boss' transformational leadership, employees' job satisfaction and job performance, and 'Cronbach's a' was used for the verification of reliability. In addition, a canonical correlation analysis was used to determine the relationship between transformational leadership, job satisfaction and job performance, and the influencing relations of variables were verified by running a multiple regression analysis through SPSS ver 18.0 statistical package in order to verify this research model and hypothesis. The results of this study can be summarized as follows: First, it was shown that the transformational leadership charisma (p<0.01) and only the individual concern (p<0.1) had a positive influence on job satisfaction. Second, as a result of understanding the impact of the transformational leadership on the job performance through a regression coefficient, it was shown that only boss' intellectual stimulation had an impact on the chef's job performance (p<0.005). Through the results of an empirical analysis that boss' transformational leadership had a correlation and a significant impact on job satisfaction and job performance, the effort of providing the systematic support and motivational aspects of supporting environment will be needed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.83-94
• /
• 2019

Recently, the importance of Total Life Cycle System Management (TLCSM) and LIFE-CYCLE COSTS management is increasing in the development of weapon systems. In cost management, cost forecasting is important from the initial development stage, but it is difficult to predict the total life cycle cost at the development stage. In this study, we propose efficient management cost calculation and management at the development stage of the weapon system by comparison analysis between the PRICE-HL model and NemoSIM to calculate the maintenance cost under the CAIV concept. Based on the study results, further in-depth analyzes of the PRICE-HL model and NemoSIM input values / results are performed. In addition, we provide a more accurate method of calculating the cost of maintaining and operating the weapon system and a plan to utilize the result of NemoSIM in the ILS element development.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.9
• /
• pp.917-925
• /
• 2006

The aim of our research was to apply experimental design methodology in the optimization of photocatalytic degradation of azo dye(Reactive orange 16). The reactions were mathematically described as a function of parameters amount of $TiO_2(x_1)$, and dye concentration($x_2$) being modeled by the use of the Box-Behnken method. The results show that the responses of color removal(%)($Y_1$) in photocatalysis of dyes were significantly affected by the synergistic effect of linear term of $TiO_2(x_1)$ and dye concentration($x_2$). Significant factors and synergistic effects for the $COD_{Cr}$, removal(%)($Y_2$) were the linear term of $TiO_2(x_1)$ and dye concentration($x_2$). However, the quadratic term of $TiO_2(x_1^2)$ and dye concentration($x_2^2$) had an antagonistic effect on $Y_1$ and $Y_2$ responses. Canonical analysis indicates that the stationary point was a saddle point for $Y_1$ and $Y_2$, respectively. The estimated ridge of maximum responses and optimal conditions for $Y_1:(X_1,\;X_2)$=(1.11 g/L, 51.2 mg/L) and $Y_2:(X_1,\;X_2)$=(1.42 g/L, 72.83 mg/L) using canonical analysis was 93% and 73%, respectively.

• Korean Journal of Food Science and Technology
• /
• v.41 no.2
• /
• pp.173-178
• /
• 2009

Epidemiological studies showed that high trans-fat consumption is closely associated with getting the risks of cardiovascular disease. The objective of this study was to produce trans-free fat through lipase-catalyzed interesterification, as a substitute for the cream margarine commonly used in industry. Optimum conditions for interesterification in a packed bed enzyme bioreactor (PBEB) were determined using response surface methodology (RSM) based on central composite design. Three kinds of reaction variables were chosen, such as substrate flow rate (0.4-1.2 mL/min), reaction temperature (60-70$^{\circ}C$), and ratio of fully hydrogenated canola oil (FHCO, 35-45%) to evaluate their effects on the degree of interesterification. Optimum conditions from the standpoint of solid fat content (SFC) were found to be as follows: 0.4 mL/min flow rate, 64.7$^{\circ}C$ reaction temperate, and 42.8% (w/w) ratio of FHCO, respectively. The half-life of immobilized lipase in PBEB with two stages at 60$^{\circ}C$ ($1^{st}$ stage) and 55$^{\circ}C$ ($2^{nd}$ stage) was about more than 30 days as estimated by extrapolating the incubation time course of tristearoyl glycerol (TS) conversion, whereas the half-life of the enzyme in PBEB with single stage at 65$^{\circ}C$ was only about 15 days. Finally, the results from SFC analysis suggest that trans-free fat produced in this study seems to be a suitable substitute for the cream margarine commonly used in industry.

• Korean Journal of Food Science and Technology
• /
• v.28 no.2
• /
• pp.345-351
• /
• 1996

Studies on extraction and color characteristics of purple sweet potato (PSP) pigment were performed to provide the basic information for the utilization of PSP as a new source of natural food colorant. PSP pigment was extracted well with the polar solvents such as distilled water, ethanol, and methanol. but hardly extracted with the non-polar solvents. Among the tested solvents, 20% ethanol solution containing 0.1% citric acid was found to be the most efficient for extraction of the pigment from PSP. PSP contained high amount of pigment not only in the epidermis but also in the flesh of the potato. The PSP pigment was heat stable even under pretreatments such as autoclaving and blanching of the potato before extraction. The optimum temperature of the extraction for the PSP Pigment was decided to be $30^{\circ}C$ by considering the stability and the rate of extraction. The pigment was markedly influenced by the change of pH. The color of the pigment solution was red at the pH range of $1.0{\sim}3.0$, became blue at $7.0{\sim}8.0$, then turned green at $9.0{\sim}10.0$. A characteristic batho-chromic shift of the pigment solution was observed as the pH of the solution increased.

• Korean Journal of Environmental Biology
• /
• v.33 no.2
• /
• pp.240-247
• /
• 2015

This study was carried out to provide the preliminary data for study of zooplankton community structures and coastal pelagic ecosystem by understanding the seasonal change of zooplankton community depending on environmental factors at Dangdong bay in Tongyeong city. In this study, the environmental factors and the change of zooplankton community were analyzed for 2008 to 2011. In the results, a total of 80 species of zooplankton was sampled with a mean density of $1,599inds.m^{-3}$. The dominant species changed seasonally, and the most dominant species was Acartia steueri in winter and spring, Penilia avirostris in summer, and Evadne nordmanni in autumn. The Canonical Correspondence Analysis was conducted between the major dominant species and environmental factors. And for the environmental factors that effect the zooplankton community, the high correlation was observed with the water temperature, COD, DO and T-N, though there was slight difference among species. Therefore, more various research and environmental study are necessary to understand of planktonic ecosystem because the zooplankton community is affected by the interaction of both physical and biological factors.

• Culinary science and hospitality research
• /
• v.16 no.3
• /
• pp.51-65
• /
• 2010

This study attempts to examine how the perception of risk and customer satisfaction influence the intention to recommend when selecting a Korean restaurant. 257 copies of the questionnaire for the Chinese students studying in Daegu and Gyeongsangbuk-do are analyzed. Three hypotheses were established and the results are as follows. First, as a result of difference analysis about perception of risk depending on dining types, there are significant differences in all factors of preception of risk partially. Second, as a result of difference analysis of customer behavior depending on dining types, there are significant differences between revisit intention and recommendation intention, and dining motivation and preferred Korean menu. Third, the effects of 6 factors of perception of risk on customer behavior are analyzed, and there are decreased customer satisfaction as the customers perceive financial and psychological crisis highly.