• Journal of Biosystems Engineering
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• 제37권3호
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• pp.192-200
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• 2012

Purpose: Aerial application of chemicals with an agricultural helicopter allows for precise and timely spraying and reduces working labor and pollution. An attitude controller for an agricultural helicopter would be helpful to aerial application operator. The objectives of this paper are to determine the transfer function models and to estimate the handling qualities of a bare-airframe model helicopter. Methods: Transfer functions of a model unmanned helicopter were estimated by using NAVFIT and DERIVID modules of the $CIFER^{(R)}$ program to the time history data of frequency sweep flight tests. Control inputs of the transfer functions were elevator, aileron, rudder and collective pitch stick positions and the outputs were resulting on-axis movements of the fuselage. Results: Minimum realization of the transfer functions for pitch rate output to elevator control input and roll rate output to aileron control input produced second order transfer functions with undamped natural frequencies around 3.0 Hz and damping ratios of 0.139 and 0.530, respectively. The equivalent time delays of the transfer functions ranged from 0.16 to 0.44 second. Sensitivity analysis of the proposed parameters allowed derivation of minimal realization of the transfer functions. Conclusions: Handling quality of the model helicopter was addressed based on the eigenvalues of the transfer functions, corresponding undamped natural frequencies with damping ratios. The equivalent time delays of the lateral-directional motion ranged from 0.16 to 0.44 second, longer than the 0.1 to 0.15 second requirement for well-controlled typical manned aerial vehicles.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.238-249
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• 2015

Purpose: Fruit and vegetable production is a fast-growing sector in East Africa, and it bears considerable local and international market potential. In an effort to analyze the challenges within this sector and suggest possible solutions, this study reviews the postharvest handling technologies commonly used with fruits and vegetables in East Africa. Methods: During the course of this study, small-scale farmers were identified as the most prominent producers of fruit and vegetable crops in the region. Results: We found that many of these small-scale farmers employed relative simple and inexpensive techniques in handling their limited volumes of produce. Several factors could be addressed to reduce postharvest losses, including weak policies, inferior infrastructure, and poor market strategies. However, the lack of basic knowledge (including demographic, scientific, and economic knowledge) among the stakeholders (e.g., researchers, farmers, governments, nongovernment organizations, and merchants) on how to develop, implement, use, and sustain the recommended handling technologies is probably the most problematic. Conclusions: We recommend that high priority be placed on closing the knowledge gap, which could enhance the efforts of all the stakeholders to address and reduce postharvest losses.

• 대한가정학회지
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• 제40권4호
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• pp.27-44
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• 2002

The purposes of this study were 1) to identify predictors of consumers′ apparel purchase on Internet shopping malls and 2) to determine reasons that respondents didn\`t have purchase intention of apparel on Internet shopping malls. The data were collected via a self-administered questionnaire from 204 male and female students who experienced shopping for apparel on Internet shopping malls, living in Cheju and analyzed by factor analysis, multiple regression analysis, t-test and paired t-test. Two predictors were found regarding purchase of apparel on the "big box" Internet shopping malls which sells various product categories; apparel quality and fun of order process. On the speciality Internet shopping malls which sells only fashion goods, diverse apparel assortment and easy handling and fun of information search were identified as predictors of apparel purchase. Reasons that respondents didn′t have purchase intention of apparel on Internet shopping malls were summarized and labeled as: difficulty of decision making due to virtual shopping environment, insufficiency of diverse apparels, users′ unease handling, risk of incredible apparel quality, unfamiliarity of Internet shopping and risks of unsecurity. Difficulty of decision making due to virtual shopping environment was determined as the most important factor of reasons that respondents didn′t have purchase intention of apparels in website.

• 기술사
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• 제30권6호
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• pp.113-120
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• 1997

This subject,'S" apartment structural frame has not been achieved without considerable effort by all quality controller involved. Therefore, it is appropriate at this time to report by all the fact of concrete quality control in our site. These are emphasized that the average strength of placed concrete must always exceed the specified value of design strength used in the structural design phase. In general, quality of ready mixed concrete largely depends not only upon the manner of production and proper observance of recognized methods of placement, finishing, curing, transportation etc. ,but also many kinds of influential factors even more handling of the test procedure, As this practical report, approaching to judgement by analysis of sampled specimens in site weather placed concrete have satisfied quality compare the specified strength with the target strength which is applied to standard deviation related with influential factors as above mentioned. This case study is consist of 1) A foreword, 2) Site brief, 3) A precondition for analysis, 4) A formulas derivation and quality analysis, 5) Economic gains by the coefRcient of increase and 6) A conclusion.sion.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.581-584
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• 2005

The performance of printer can be determined lots of factors such as the printing speed, resolution, image quality, first page out time, paper handling performance and acoustic noise. Among them, acoustic noise and image quality are closely related to the mechanism vibration in the printing operation. To improve these quality, it is important to understand the functions of all individual parts and their relations to entire system. In this paper, the principle of LBP is briefly explained and then the characteristics of printing noise and image banding are explained.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.282-285
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• 2003

Two criteria of good vehicle suspension performance are typically their ability to provide good road handling and increased passenger comfort. So far, The existing active vehicle suspension uses pneumatic and hydraulic actuators that enhance road handling and passenger comfort. But these kinds of actuators have nonlinear characteristic less than an electromagnetic motor. In this research, we are trying to examine the feasibility and the experiment of an active vehicle suspension using electromagnetic motor in order to enhance the ride quality because existing active vehicle suspension using active power sources such as compressors, hydraulic pumps has nonlinear characteristic. Active vehicle suspension using electromagnetic motor will have the ability to behave differently on smooth and rough roads. The desired response should be soft in order to enhance ride comfort, but when the road surface is too rough the suspension should stiffen up to avoid hitting its limits.

• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.824-836
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• 2008

Relaxed static stability(RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. Therefore, flight control systems are necessary to stabilize an unstable aircraft, and provides adequate handling qualities and achieve performance enhancements. Standard FCSDVP (Flight Control System Design and Verification Process) is provided to reduce development period of the flight control system. In addition, if this process is employed in developing flight control system, it reduces the trial and error for development and verification of flight control system. This paper addresses the flight control system design and verification process for the RSS aircraft utilizing design goal based on military specifications, linear and nonlinear system design and verification based on universal software, handling quality test based on HILS(Hardware In-the-Loop Simulator) environment, and ground and flight test results to verify aircraft dynamic flight responses.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.739-744
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• 2009

The filter has long been used in purification processes for indoor air quality. To determine the deodorization effect of several filter materials in a full-scale air-handling system, the present study has been carried out using a wind tunnel equipped with a heat exchanger and various filter materials, such as commercial fabric, activated carbon(AC) and silver nano-particles attached to activated carbon(Ag-AC). The experiment was conducted using an odor substance with ammonia, acetaldehyde, acetic acid. The results obtained indicate that odor substance is substantially decreased on the moisture condensation on the surface of the heat exchanger. The fabric filter has no effect for removal of odor substances. The deodorization efficiency is found to be approximately 7% in the AC filter, while the deodorization efficiency is increased up to 10% using the Ag-AC filter.

• 한국식생활문화학회지
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• 제10권3호
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• pp.167-174
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• 1995

A hazard analysis which included watching operations, measuring temperatures of foods throughout preparation and display, and sampling and testing for microorganisms of total plate counts and coliform bacteria was conducted in various phases of product flow of Naeng-myeun (Cold noodles) and Pi-bim bab (mixed rice) prepared at Korean restaurants. Large numbers of total plate counts were counted from the cooked foods after handling and holding. Ingestion of these foods must be considered high risk. Critical control points identified were, pre-preparation, food handling after cooking, and holding on display in product flow of Nang-Meon and pre-preparation, preparation, and holding on display in product flow of Pi-bim bab. It need for effective quality control of Nang-Meon and Pi-bim bab that training program consist of surveillance, education of the staff, standard operation procedures, forbidding dangerous processes and control of critical points.

• 대한산업공학회지
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• 제37권4호
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• pp.271-278
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• 2011

This paper is to review and organize performance strategies, issues, and measures for the efficient operation of order picking function. Order picking is the process of retrieving items from storage to meet a specific customer order, which is known to be the most labor-intensive and costly function among all the warehouse functions. This function is also important in that it has a critical impact on downstream customer service. For understanding the background of order picking and related performance issues, we will briefly introduce warehousing functions. Then we will introduce material handling within a warehouse and order picking strategies. Lastly, we will discuss about performance issues and measures in the domain of order picking operations. Productive and quality measures will be reviewed in more detail.