• Journal of Biosystems Engineering
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• 제23권1호
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• pp.57-66
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• 1998

This study was conducted to investigate the relationships between parameters affecting internal quality of watermelon and its acoustic characteristics. The measuring and analyzing system was established to study the acoustic characteristics of watermelon. Algorithms for analyzing sound signals were developed. Sound signals which was detected with the microphone were filtered, and their spectrum was computed by means of the Fast Fourier Transform. As watermelon changed from the unripe stage to ripe, acoustic waves in time domain became complicated, and several components appeared in frequency domain. The correlationship was investigated between some parameters affecting internal quality of the watermelon and several peak frequencies. Results indicated that weight, density and sugar content had high correlations with several frequencies(the first peak frequency, the second peak frequency, and the third peak frequency). And the sugar content and the volume of the watermelon were highly correlated with the third peak frequency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.969-972
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• 1988

A conventional robotic manipulator is usually a very complicated system whose dynamics is too computationally time consuming for dynamic analysis and real time control. The authors have proposed the general design criteria of the robot links which greatly simplify the robot dynamic characteristics. In this paper these design guidelines are applied to a 6 degree of freedom PUMA 560 robot in order to realize actual implementation of the design concept. Based upon the design concept, the dynamic equations of the redesigned robot were derived. Dynamic characteristics of two systems, the ideally designed and conventional robot, are compared with respect to the joint input torque characteristics and degree of the coupling between the robot joints.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.398-404
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• 1999

The EGR is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate the intake and exhaust system become complicated. That is a reason why we consider using the built0in EGR system. The built-in EGR is a system which reduces Nox by controling the residual gas fraction in cylinder by changing valve timing and valve lift of intake and exhaust. In this paper characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust. In this paper characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust in the 4 stroke-cycle diesel engine. Volumetric efficiency and residual gas fraction were calculated by the method of characteristics. As the results the possibility of suing the built-in EGR system was confirmed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.829-834
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• 2000

This paper is primarily directed toward analyzing the transient response characteristics in hydraulic pipe lines. The exact solution to the transient response characteristics was obtained by using the complicated transfer function derived by Iberall. The discrepancy with the exact and approximate is small, so the approximate solution is adopted to the theoretical one. An equation was derived which describes the pressure times relationship Hat occurs at the end of volume terminated transmission line following a sudden pressure change at its inputs. As a result, It is found that the density has relationship about the Wave Propagation is very useful in analyzing the transient response characteristics of hydraulic pipe lines. The velocity of Pressure wave Propagation decreases as the density of fluid increased.

• Journal of Advanced Marine Engineering and Technology
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• 제14권3호
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• pp.34-41
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• 1990

Mode Synthesis Method is applied to analyize the vibration characteristics of the press machine sold at present. Vibration analysis of the machine has not been done thoroughly as far, because of its complicated structure and much bigger unlinearity of its vibration characteristics. The press was disassembled by parts, and it was experimented by the exciting techniques and curve fitting methods, and analyzed by the Mode Synthesis Method. The 2 results were showed good agreements at each part. We confirming it, the machine was assembled, and experimented and analyzed by the same method. Also good agreements between 2 methods were obtained. In addition, impact responses of the actual moving press were agreed with the analyzed values by the Mode Synthesis Method. And we found that the first bending mode of the slide was ruling the vibration characteristics of the press.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.559-562
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• 2000

The problem of noise generation due to PWM switched-mode power converter has been widely noticed from the viewpoint of Electromagnetic Interference(EMI). Many kings of topologies for resonant converters have been developed both to overcome this noise problem and to attain high power efficiency. It is reported in references that resonant converters which are derived from PWM converter using resonant switch show much lower noise characteristics than PWM converter, and that current-mode resonant converter is more sensitive to stored charge in rectifying diode than voltage-mode counterpart concerning surge generation at diode’s turn-off. On the other hand, above mentioned resonant converters have defect of high-voltage stress on semiconductor switch and complicated circuit configuration. Hence, the simplified Forward-type resonant converter has been proposed and investigated due to its prominent features of simplicity of circuit configuration, low voltage stress and high stability. However, its noise characteristics still remain unknown. The purpose of this paper is to study quantitatively the noise characteristics of this simplified Forward-type resonant converter by experiment and analysis. The influence of parasitic elements and stored charge in rectifying diode on noise generation has been clarified.

• 한국실내디자인학회논문집
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• 제29호
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• pp.163-172
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• 2001

An office is understood as a system consisted of three subsystem : office work, technology and organization. In the age of information, an office is a complicated device in an organization to create, process, modify and deliver various information for organizational goals. The purpose of this study is to provide design guidelines on office workstations based on the analysis of employees' preference and work-style responding to current changes of an organization and work process. Through a literature survey, the study briefly reviewed characteristics of interior design to find changing factors and directions of office interior. Work characteristics in an office are analyzed based on information, activity and communication characteristics while office environment is analyzed based on physical and technological factors. Finally, questionnaire items are derived from a critical comparison between work characteristics and workstation organization(furniture etc) factor. workplace strategies by preference are suggested to increase office productivity, employee satisfaction and to reduce space costs.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.191-194
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• 2008

Labyrinth weir is a hydraulic structure that can maintain constant water depth and increase overflow rate by increasing overflow width of weir through complicated displacement of its cross section. The labyrinth weir can be widely applied to various hydraulic facilities such as dam spillway, irrigation facilities, and canal structures. To date, however, few labyrinth weirs were applied to hydraulic facilities in Korea. Hence, in-depth research on labyrinth weir is highly required to efficiently apply the labyrinth weir to hydraulic facilities. This study was performed to analyze the hydraulic characteristics according to triangle labyrinth weir using hydraulic model experiments. The hydraulic characteristics provided in this study, which make it feasible to increase the overflow rate, and are expected to be widely applied to design of hydraulic facilities such as dam spillway and irrigation system.

• 대한전자공학회논문지SD
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• 제38권12호
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• pp.25-35
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• 2001

복잡한 thin film transistor-liquid crystal display (TFT-LCD) array 회로의 전기적 특성을 분석하기 위해서는 PSPICE나 AIM-SPICE와 같은 회로 시뮬레이터를 사용하는 것이 필수적이다. 본 논문에서는 SPICE 시뮬레이션을 위한 다결정 실리콘 (poly-Si) TFT 소자의 입력 변수 추출을 체계화하는 방법을 도입한다. 이 방법을 excimer laser annealing 및 silicide mediated crystallization 방법으로 각각 제작된 다결정 실리콘 TFT 소자에 적용하여 실험 결과와 잘 일치하는 결과를 얻었다. SPICE 시뮬레이터 중에서 PSPICE는 graphic user interface(GUI) 방식의 편의성을 제공하므로 손쉽게 복잡한 회로를 구성할 수가 있다는 장점이 있으나, poly-Si TFT 소자 모델을 가지고 있지 않다. 이 연구에서는 PSPICE에 다결정 실리콘 TFT 소자 모델을 이식하고, TFT가 이식된 PSPICE를 사용하여 poly-Si TFT-LCD 단위 화소 및 라인 RC 지연을 고려한 화소에 대한 전기적 특성을 분석하였다. 이러한 결과는 TFT-LCD 어레이 특성 분석을 위한 시뮬레이션을 효율적으로 수행하는데 기여할 수 있을 것으로 기대된다.

• Journal of Chest Surgery
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• 제44권4호
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• pp.279-284
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• 2011

Background: The aim of this study is to investigate the clinical characteristics and management of intrathoracic bronchogenic cysts. Materials and Methods: Twenty-four (n=24) patients with intrathoracic bronchogenic cysts were treated surgically between August 1990 and December 2009 at our institution. Patients were divided into two groups by bronchogenic cyst location: mediastinal or intrapulmonary. Symptoms at diagnosis, radiologic findings, locations, surgical methods, pathological findings, and surgical outcomes were investigated retrospectively from consecutive patient medical records. Results: There were 12 females (50.0%). The mean age was 26.8 (range, 5 to 64) years. The mean follow-up period was 27.3 (range, 1 to 121) months. There were 15 (62.5%) mediastinal and 9 (37.5%) intrapulmonary bronchogenic cysts. Symptoms occurred in 8 patients with mediastinal bronchogenic cysts (53.3%) and 5 patients with intrapulmonary bronchogenic cysts (55.6%) (p=1.000). On computed tomography (CT), 7 patients (46.7%) showed homogenous solid masses in mediastinal bronchogenic cysts and five (55.6%) patients exhibited heterogeneous cystic masses with air-fluid levels in intrapulmonary bronchogenic cystic masses. Open thoracotomy was performed in 17 (70.8%) patients, and video-assisted thoracic surgery was performed in 7 (29.2%) patients. On pathological findings, there were 16 (66.7%) complicated cysts, and in 13 symptomatic patients, 11 (84.6%) patients had complicated cysts. There was no operative death in this study. During the follow-up period, no recurrence was detected. Conclusion: Intrathoracic bronchogenic cysts have a wide variety of clinical characteristics and radiologic findings. Even though some patients do not experience symptoms and signs caused by bronchogenic cysts, serious symptoms and complications may develop with the passage of time.