• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.578-582
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• 1995

The resonance ionization mass spectrometry (RIMS) system with angular reflectron type time-of-flight mass spectrometer (AREF-TOFMS) has been developed and characterized. The system is applied for the ultratrace determination of Pb element. The 2-color 3-photon laser ionization scheme is adopted for the study and the mass resolution of the system is determined as T/ΔT=1680. The calibration curve for Pb is obtained in the range of 100 ppb to 0.01 ppb by using standard solutions. The minimal amount of detection for the present RIMS system is determined as less than 100 femtograms (10-13 gram).

• Journal of Biosystems Engineering
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• 제43권2호
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• pp.103-109
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• 2018

Purpose: This study has been conducted to develop a potato yield monitoring system, consisting of a segmentation algorithm to detect potatoes scattered on a soil surface and a counting system to count the number of potatoes and convert the data from two-dimensional images to masses. Methods: First, a segmentation algorithm was developed using top-hat filtering and processing a series of images, and its performance was evaluated in a stationary condition. Second, a counting system was developed to count the number of potatoes in a moving condition and calculate the mass of each using a mass estimation equation, where the volume of a potato was obtained from its two-dimensional image, and the potato density and a correction factor were obtained experimentally. Experiments were conducted to segment potatoes on a soil surface for different potato sizes. The counting system was tested 10 times for 20 randomly selected potatoes in a simulated field condition. Furthermore, the estimated total mass of the potatoes was compared with their actual mass. Results: For a $640{\times}480$ image size, it took 0.04 s for the segmentation algorithm to process one frame. The root mean squared deviation (RMSD) and average percentage error for the measured mass of potatoes using this counting system were 12.65 g and 7.13%, respectively, when the camera was stationary. The system performance while moving was the best in L1 (0.313 m/s), where the RMSD and percentage error were 6.92 g and 7.79%, respectively. For 20 newly prepared potatoes and 10 replication measurements, the counting system exhibited a percentage error in the mass estimation ranging from 10.17-13.24%. Conclusions: At a travel speed of 0.313 m/s, the average percentage error and standard deviation of the mass measurement using the counting system were 12.03% and 1.04%, respectively.

• Smart Structures and Systems
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• 제13권2호
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• pp.219-233
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• 2014

In a companion paper, Pasala and Nagarajaiah analytically and experimentally validate the Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) on a primary structure (2 story steel structure) whose frequencies are time invariant (Pasala and Nagarajaiah 2012). In this paper, the ALP-STMD effectiveness on a primary structure whose frequencies are time varying is studied experimentally. This study experimentally validates the ability of an ALP-STMD to adequately control a structural system in the presence of real time changes in primary stiffness that are detected by a real time observer based system identification. The experiments implement the newly developed Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) which was first introduced and developed by Nagarajaiah (2009), Nagarajaiah and Pasala (2010) and Nagarajaiah et al. (2010). The ALP-STMD employs a mass pendulum of variable length which can be tuned in real time to the parameters of the system using sensor feedback. The tuning action is made possible by applying a current to a shape memory alloy wire changing the effective length that supports the damper mass assembly in real time. Once a stiffness change in the structural system is detected by an open loop observer, the ALP-STMD is re-tuned to the modified system parameters which successfully reduce the response of the primary system. Significant performance improvement is illustrated for the stiffness modified system, which undergoes the re-tuning adaptation, when compared to the stiffness modified system without adaptive re-tuning.

• 산업공학
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• 제10권2호
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• pp.91-97
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• 1997

A mass production system was implemented to reduce a manufacturing cost in a way of copying with a strong world market competition. However customer's demands are changing so rapidly and the mass production system is no longer competitive to meet the demands. FMS(Flexible Manufacturing System) has been introduced as a replacement for the mass production system, but it still does not meet system's requirements. A new manufacturing system, called a holonic manufacturing system (HMS), is emerging. This paper is giving a first approach of a HMS for a multirobot cooperative process.

• 대한의용생체공학회:의공학회지
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• 제30권2호
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• pp.153-161
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• 2009

Mammogram is one of the important techniques for mass detection, which is the early diagnosis stage of a breast cancer. Especially, the CAD(Computer Aided Diagnosis) using mammogram improves the working performance of radiologists as it offers an effective mass detection. There are two types of CAD systems using mammogram; automatic and semi-automatic CAD systems. However, the automatic segmentation is limited in performance due to the difficulty of obtaining an accurate segmentation since mass occurs in the dense areas of the breast tissue and has smoother boundaries. Semi-automatic CAD systems overcome these limitations, however, they also have problems including high FP (False Positive) rate and a large amount of training data required for training a classifier. The proposed system which overcomes the aforementioned problems to detect mass is composed of the suspected area selection, the level set segmentation and SVM (Support Vector Machine) classification. To assess the efficacy of the system, 60 test images from the FFDM (Full-Field Digital Mammography) are analyzed and compared with the previous semi-automatic system, which uses the ANN classifier. The experimental results of the proposed system indicate higher accuracy of detecting mass in comparison to the previous systems.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.707-714
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• 2016

We present a piezoelectric energy harvester with stopper-engaged dynamic magnifier which is capable of significantly increasing the operating bandwidth and the energy (power) harvested from a broad range of low frequency vibrations (<30 Hz). It uses a mass-loaded polymer beam (primary spring-mass system) that works as a dynamic magnifier for another mass-loaded piezoelectric beam (secondary spring-mass system) clamped on primary mass, constituting a two-degree-of-freedom (2-DOF) system. Use of polymer (polycarbonate) as the primary beam allows the harvester not only to respond to low frequency vibrations but also generates high impulsive force while the primary mass engages the base stopper. Upon excitation, the dynamic magnifier causes mechanical impact on the base stopper and transfers a secondary shock (in the form of impulsive force) to the energy harvesting element resulting in an increased strain in it and triggers nonlinear frequency up-conversion mechanism. Therefore, it generates almost four times larger average power and exhibits over 250% wider half-power bandwidth than those of its conventional 2-DOF counterpart (without stopper). Experimental results indicate that the proposed device is highly applicable to vibration energy harvesting in automobiles.

• 동력기계공학회지
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• 제13권6호
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• pp.70-75
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• 2009

In this paper, cycle performance analysis of R744($CO_2$) two-stage compression and one-stage expansion refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include superheating degree, compressor efficiency, gas cooling pressure, mass flowrate ratio, outlet temperature of gas cooler and evaporating temperature in the carbon dioxide two-stage refrigeration cycle. The main results were summarized as follows : The cooling capacity of two-stage compression and one-stage expansion refrigeration system increases with the increasing superheating degree, compressor efficiency and gas cooling pressure, but decreases with the increasing mass flowrate ratio and evaporating temperature. The compression work of two-stage compression and one-stage expansion refrigeration system increases with the increasing superheating degree, outlet temperature of gas cooler, gas cooling pressure and evaporating temperature, but decreases with the increasing compressor efficiency and mass flowrate ratio. The COP of two-stage compression and one-stage expansion refrigeration system increases with the increasing compressor efficiency, but decreases with the increasing superheating degree, gas cooling pressure, mass flowrate ratio and evaporating temperature. Therefore, superheating degree, compressor efficiency, gas cooling pressure, mass flowrate ratio, outlet temperature of gas cooler and evaporating temperature of R744($CO_2$) two-stage compression and one-stage expansion refrigeration system have an effect on the cooling capacity, compressor work and COP of this system.

• 품질경영학회지
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• 제44권3호
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• pp.541-552
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• 2016

Purpose: In this study, we propose that how to approach a effective system engineering and optimize system engineering management process for the mass production weapon system parts localization development process and success in DTaQ. Methods: To approach a effective system engineering for the mass production weapon system parts localization, we analyze a weapon system acquisition process and system engineering process of Republic of Korea and DTaQ parts localization business regulations in advance. after results of analysis of them, we implement a optimized parts localization development system engineering based on ISO/IEC/IEEE 15288. Results: In order to apply International Standard ISO/IEC/IEEE 15288 to the mass production weapon system parts localization development process, we compare the mass production weapon system parts localization acquisition environment with ISO/IEC/IEEE 15288 and analyze them. therefore, It is possible to implement a part of concept stage and development stage of ISO/IEC/IEEE total life cycle stage for the mass production weapon system parts localization development process. To achieve the technical review milestones of DTaQ parts localization business regulations in the selected stages of ISO/IEC/IEEE, the development and management agency perform 2 high rank process and 19 low rank process specified in ISO/IEC/IEEE. Conclusion: When the development and management agency perform the mass production weapon system parts localization development using the proposed system engineering approach, they should easily meet milestone through the clarified requirement and simplified System Engineering output documents in limited development period.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.122-128
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• 2003

This paper presents a thermodynamic analysis of heat pump system using water as a heat source and heat sink. The primary object in this study is the optimization of exergetic efficiency. Two different systems, 2-stream and 1-stream system, are analyzed in detail. Mass flow ratio (the ratio of mass flow rate of water through evaporator to that through condenser) is identified as the most important parameter to be optimized. It is shown that there exists an optimum mass flow ratio to maximize exergetic efficiency. The variation of optimum exergetic efficiency of 2-stream system is quite small and the value lies between 0.2∼0.23 for the range of investigation in this study. However, far better performance can be obtained from 1-stream system. This means considerable irreversibilities are generated through condenser of the 2-stream system. The effects of adiabatic efficiency of compressor-motor unit on the overall system performance are also examined in the analysis.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.445-452
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• 1998

The dynamic performance design of catenary-pantograph system which collects current for the next generation Korean high speed train(KHST) was considered. Used was the same dynamic model of the catenary-pantograph system as that of TGV-K which will be introduced for Kyung-bu corridor. Using the model , sensitivity analysis fer design variables were made to improve dynamic performance of KHST system. The results of sensitivity analysis and performance improvement are as follows: (1) It was found that aerodynamic force, tension of contact wire, mass of contact strip, mass of supporting contact strip, mass of clamp, mass of steady arm, and stiffness of plunger were the design variables most influencing the dynamic performance of the system. (2) Pantograph with reductions of 20% aerodynamic force, 34% weight of supporting contact strip, 20% spring constant of plunger, and 34% equivalent mass of steady arm was very possible system for the KHST which will be running at maximum operating speed 350 km/h.