• Journal of Biosystems Engineering
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• 제23권3호
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• pp.211-218
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• 1998

A variable flow-controlled boom sprayer was developed and evaluated. Field tests were conducted to evaluate the adoptability of the sprayerr with optimal conditions. Negative response time was obtained from the field test because pump and PTO were interlocked with the speed of sprayer. Another reason for the negative value was due to the definition of the response time. With constant on-time control, the system was unstable at the conditions of small tolerance and long control interval. The performances of the spray system were stable and accurate. The stable and synchronous responses were achieved with a variable on-time control. The flow control system with an optimal condition (1.0 sec of control interval, 2 of damping ratio, 1% of tolerance) provided the proper performance for uniform spraying. A standard operating procedure of the flow compensating boom sprayer for the ground speed variation was presented and recommended.

• 한국작물학회지
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• 제48권5호
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• pp.407-412
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• 2003

In order to measure an antifreezing tolerance, antifreeze proteins accumulated upon cold acclimation in apoplast were analyzed. As Dongborilho were cold-acclimated for 3 to 74 days there was an abrupt increase in apoplastic proteins up to 30 days and then decrease to the similar levels. Among the known antifreeze proteins, CLP produced in E. coli. and TLP purified from apoplast were used to generate antisera that allow to measure and localize the proteins in leaves of barley. The CLP of 27.7 kDa and TLPs of 6, 26, 27, 30, and 31 kDa were increased in their amounts in apoplast as cold treatment being longer. There was a correlation among the amounts of those proteins accumulated in apoplast and freezing tolerance as shown in field and ion leakage tests for five cultivars. The deposit of CLP was localized in the marginal area and the area adjacent to leaf vescular bundle cells in an increasing manner according to duration of cold acclimation but no variation was observed in terms of it's distribution. Based on the close correlation between levels of antifreeze proteins and degrees of freezing tolerance, the immunological methods was to develop to estimate a freezing tolerance in barley.

• 한국응용곤충학회지
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• 제54권4호
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• pp.303-310
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• 2015

배추좀나방(Plutella xylostella)은 시설재배지를 중심으로 국내 자연 상태에서 월동한다. 안동지역에서 이른 봄부터 배추좀나방 성페로몬트랩을 이용하여 배추좀나방의 성충 발생 시기를 주기적으로 조사한 결과 연중 4 회의 성충 발생 피크를 보였다. 월동 집단을 대상으로 서로 다른 지역 집단 간 생물적 특성을 조사한 결과 내한성, 약제감수성 및 발육속도에서 뚜렷한 집단 특성을 나타냈다. 분자마커로 집단변이를 분석한 결과 월동세대의 높은 집단변이는 계절이 진행됨에 따라 낮아지는 양상을 나타냈다. 이 결과는 배추좀나방의 국내 월동 집단 사이의 생물적 특성 차이를 나타냈고, 이들의 높은 유전적 분화는 계절이 진행됨에 따라 감소하여 이들 집단 사이의 개체들의 이동에 따른 유전적 교환이 이뤄졌다는 것을 제시했다.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.67-72
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• 2005

This study proposes a design methodology to determine the optimum configurations of the optical flying head (OFH) for near-field recording systems. Since the OFH requires stricter static and dynamic characteristics of slider air-bearings within an optical tilt tolerance over the entire recording band, an optimum design to keep the focusing and tracking ability stable is essential. The desired flying characteristics considered in this study are to minimize the variation in flying height between the SIL and the disk from a target value, satisfying the restriction of the minimum flying height, to keep the pitch and roll angles within an optical tilt tolerance, and to ensure a higher air-bearing stiffness. Simulation results demonstrate the effectiveness of the proposed design methodology by showing that the static and dynamic flying characteristics of the optimally designed OFH are enhanced in comparison with those of the initial. The gap between the SIL and the disk can be kept at less than 100 nm even if the optical tilt tolerance of the SIL is considered.

• 산업경영시스템학회지
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• 제30권2호
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• pp.37-43
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• 2007

ANOVA is widely used for measurement system analysis. It assumes that the measurement error is normally distributed, which may not be seen in certain industrial cases. In this study, the exact and bootstrap confidence intervals for precision-to-tolerance ratio (PTR) are obtained for the cases where the measurement errors are normally and non-normally distributed and the reproducibility variation can be ignored. Lognormal and gamma distributions are considered for non-normal measurement errors. It is assumed that the quality characteristics have the same distributions of the measurement errors. Three different bootstrap methods of SB (Standard Bootstrap), PB (Percentile Bootstrap), and BCPB (Biased-Corrected Percentile Bootstrap) are used to obtain bootstrap confidence intervals for PTR. Based on a coverage proportion of PTR, a comparative study of exact and bootstrap methods is performed. Simulation results show that, for non-normal measurement error cases, the bootstrap methods of SB and BCPB are superior to the exact one.

• 품질경영학회지
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• 제25권2호
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• pp.140-153
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• 1997

As product quality is maily determined in the product design and process design step, systematic design should be performed through parameter design and tolerance design. Therefore, we introduced analysis of variance and regression analysis as a statistical method which determine optimal levels of affective design factors to product characteristics, then we compared that process and result. In analysis of variance, variation of quality characteristics arises from noise factors, so the optimal levels of design factors are selected to minimize the effect of noise factors. In regression analysis, variation of quality characteristics aries from variation of each own design factors. As a method to reduce variation of these quality characteristics, sensitivity analysis was performed about each design factors. Through this sensitivity analysis, we represented process to calculate the interaction term of the factors.

• 아시안잔디학회지
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• 제13권1호
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• pp.37-54
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• 1999

This study was initiated to evaluate the seasonal turf performance in a tree shade and to suggest shade-tolerant turfgrasses suitable for domestic climate conditions. Atotal of 21 trufgrasses were tested, comprising of Korean lawngrass, shade-tolerant fine fescues, and newly-developed, shade-tolerant varieties of cool-season grasses. Dirrerences in shade tolerance were observed among varieties, species, and genera. Overall turf performance of C3 turfgrasses was better than that of C4 Korean lawngrass under a tree shade. Coarse-type fescues were excellent in shade tolerance, bluegrasses good, ryegrasses medium, fine-type fescues fair, and zoysiagrasses poor, respectively. Inter-species comparison in relative index of shade tolerance(IRST) demonstrated that tall fescue and fough bluegrass were greatest of 7.3, Poa supina 6.4, perennial ryegrass 5.0, Kentucky bluegrass 4.8, and fine fescues least, respectively. A great variation in RIST was observed with fine fescues; creeping red fescue was 3.6, chewings fescue 2.5, hard fescue 2.1, and sheep fescue 1.4, respectively. Among 21 turfgrasses evaluated, tall fescue 'Rebel Jr.', 'Era', and 'Oixie' and rough bluegrass 'Sabre' were the shade-tolerant varieties under a tree shade in Korea. Tall fescue, 'Rebel Jr.' was considered as the most shade-tolerant variety in the experiment. Fine fescues as creeping red fescue, chewings fescue, hare fescue, and sheep fescue, used as the shade-tolerant species in a cool climate of Europe and North America, were not suitable under domestic climate conditions.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.

• 한국생산제조학회지
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• 제19권5호
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• pp.609-615
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• 2010

Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.

• 품질경영학회지
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• 제22권4호
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• pp.79-101
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• 1994

In modern manufacturing, a product consists of many components created by different processes. Variations in the individual component dimensions and in the processes may result in unacceptable final assemblies. Thus, engineers have increased pressure to properly set tolerance specifications for individual components and to control manufacturing processes. When a proper variation stack-up analysis is not performed for all of the components in a functional system, all component parts can be within specifications, but the final assembly may not be functional. Thus, in order to improve the performance of the final assembly, a proper variation stack-up analysis is essential for specifying dimensional tolerances and process control. This research provides a detailed case example of the use of variation stack-up analysis using a Monte Carlo simulation method to improve the defect rate of a complex process, which is the commutator brush track undercut process of an armature assembly of a small motor. Variations in individual component dimensions and process mean shifts cause high defect rate, Since some dimensional characteristics have non-normal distributions and the stack-up function is non-linear, the Monte Carlo simulation method is used.