• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.537-543
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• 2003

Condition monitoring and fault diagnosis of machines are gaining importance in the industry because of the need to increase reliability and to decrease possible loss of production due to machine breakdown. By comparing the vibration signals of a machine running in normal and faulty conditions, detection of faults like mass unbalance, shaft misalignment and bearing defects is possible. This paper presents a novel approach for applying the fault diagnosis of rotating machinery. To detect multiple faults in rotating machinery, a feature selection method and support vector machine (SVM) based multi-class classifier are constructed and used in the faults diagnosis. The results in experiments prove that fault types can be diagnosed by the above method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.865-867
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• 2001

Generally large synchronous rotating machines with 2 poles have more merits than the others with more than 2 poles Superconducting synchronous rotating machines also have the same tendency, but they have different structure from conventional ones because of no magnetic core inside of the rotor. As the result, design approaches of the superconducting field coils are also different, which would be classified into 2 types according to their coil shapes. The first one is race-track type and the other is saddle type Race-track type machines have almost the same structure with conventional salient pole generators which are being used as largely small scale machines with more than 2 poles. On the other hand saddle type machines correspond to conventional cylindrical generators with 2 poles used for large turbine system in power plants. In this paper several types of superconducting field coils are introduced for 2 pole superconducting machine design and then the feasibility of each type is considered. Moreover, based on the consideration. 1MVA superconducting generator(S.G.) with saddle type field coil is designed electromagnetically.

• Journal of Biosystems Engineering
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• 제31권5호
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• pp.403-409
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• 2006

This study was performed to design a peeling device for root crop that were considered of the three possible types such as blade belt type, brush type, and rotating blade type, and to inspect the characteristics of the experimented peeling methods based on the chonggag (altari) radish tests. The peeling performances by the blade belt type and brush type devices were not established so well with the troublesome like adhesion of the chip on the blades was occurred, and the difficulties to produce the blade parts were come out on these types of the peeling devices. But the peeling operations by the rotating blade type peeling device was completed without needs to clean blades, and it was concluded that it would be possible to practical mechanization of the root crop which shaped similar chonggag radish for it's constructional simplicity and feasibility.

• Steel and Composite Structures
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• 제42권3호
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• pp.375-388
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• 2022

In this work, limit elastic speed analysis of functionally graded porous rotating disks has been reported. The work proposes an effective approach for modeling the mechanical properties of a porous functionally graded rotating disk. Four different types of porosity models namely: uniform, symmetric, inner maximum, and outer maximum distribution are considered. The approach used is the variational principle, and the solution has been achieved using Galerkin's error minimization theory. The study aims to investigate the effect of grading indices, aspect ratio, porosity volume fraction, and porosity types on limit angular speed for uniform and variable disk geometries of constant mass. To validate the current study, finite element analysis has been used, and there is good agreement between the two methods. The study yielded a decrease in limit speed as grading indices and aspect ratio increase. The porosity volume fraction is found to be more significant than the aspect ratio effect. The research demonstrates a range of operable speeds for porous and non-porous disk profiles that can be used in industries as design data. The results show a significant increase in limit speed for an exponential disk when compared to other disk profiles, and thus, the study demonstrates a range of FG-based structures for applications in industries that will not only save material (lightweight structures) but also improve overall performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.88-95
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• 1997

In this paper, we present an efficient method for finite element vibration analysis of constantly rotating blade disks which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A blade disk which is a structure with cyclic symmetry is divided into substructures with the same geometry. Only one substructure is modeled and can be analysed rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.91-91
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• 2011

This paper describes development procedure of the four types of fuel cell's blowers: pressurized fuel blower, selective oxidation air blower, cathode air blower, and burner air blower. Diaphragm blowers having two heads are selected to maintain force balance when the rotating arms are moving by the driving motor. Dimensions of a diaphragm cavity is designed according to the optimal design procedure using numerical simulation and experimental measurement. Experimental apparatus is designed by considering the bower characteristics having low flow rate and high pressure. Test blower is operated by a diaphragm, which has suction and discharge port on the top of the blower. For analyzing the internal flow of the blower, three-dimensional Navier-Stokes analysis is introduced in the present study. Throughout the optimal design of the blowers, blower performance is enhanced by reducing the unbalance motion of the rotating arm and loss region in the diaphragm cavity.

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.122-128
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• 2004

With the advent of distributed generation, power systems are fundamentally impacted in regards to stability and power quality. Distributed generation has a positive impact on system restoration following a fault, higher reliability, and mitigation of effect due to voltage sag. However, distributed generation also has a negative impact on decrease of reliability such as changes of protective device setting and mal-operation. Because bulk power systems consist of various sources and loads, it becomes complicated to analyze a power system with distributed generation. The types of distributed generation are usually classified by both rotating machinery and the inverter-based system. In this paper, distributed generation is designed by rotating machinery, and the distributed system having a model of the distributed generation is simulated using EMTP. In addition, this paper presents the simulation results according to the types of distributed generation.

• 한국직업건강간호학회지
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• 제9권2호
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• pp.86-93
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• 2000

This study was conducted to find out the degree of tiredness, accumulated tendencies of fatigues in accordance with 3 types of circadian rhythms and 3 types of perceived fatigue signs such as physical, psychological and neurosensory aspects in before and after work at night. Samples were chosen from the 217 intensive care units nurses working in 13 general hospitals which had 3 shift rotating systems, Data were collected from November to December in 1999. Two hundreds seventeen respondents were classified by 3 circadian types such as 59 morning, 110 middle and 48 evening. Circadian type was measured by the circadian type scale which was designed by ${\ddot{O}}stberg$ and Home (1976). in order to estimate the level of tiredness, the investigator used the fatigue checklist designed by the Labor and Health Institute of Japan(1970). Analysis was done by frequency a percentages, ${\chi}^2$ test and repeated measures ANOVA test. The result of this study were as follow: 1. In the general characteristics of the subjects circadian types, moderate type had the large proportion at 50.7% and morning type had 27.2% and evening type had 22.1%. 2. According to the 3 types of fatigue signs, the highest general tendency was 'General weakness' and 'Feeling of headsore' for physically perceived sign, 'Drowsiness' for psychological sign, and 'Uncomfortableness in sight seeing' for neurosensory sign. 3. The most frequently complained fatigue were observed in physical symptoms among physical, mental, and neurosensual symptoms. The percentage of complained was higher after night work than before the work started. 4. There was not any statistical significant difference between the circadian type and the degree of physical, mental, neurosensory fatigue. 5. There was not any statistical significant difference in regarding to each date of night shift except difference between 1st and 2nd days of fatigue perceived physically. Therefore, the study concluded that the fatigue perceived by night shift nurses might be related with shift working condition rather than circadian types.

• 한국유체기계학회 논문집
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• 제1권1호
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• pp.58-63
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• 1998

To investigate turbine flow fields under realistic conditions, a rotating turbine test facility has been developed at the Inha University Propulsion Laboratory. The experimental facility consists of an air inlet, settling chamber, single turbine stage test section, and diffuser. This turbine has a design flow coefficient of 0.55 and work coefficient of 1.88. The turbine test rig has four features. First, a large scale test section improves space resolution. Second, low speed rpm enhances safety and reduces required power, Third, DC motor/generator is able to regenerate blower power. Fourth, various types of experiment can be carried out.

• 소음진동
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• 제8권6호
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• pp.1150-1157
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• 1998

In this Paper, we present an efficient method for finite element vibration analysis of constantly rotating structures with cyclic symmetry, which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A structure with cyclic symmetry is composed of circumferentially repeated substructures with the same geometry. Being only one substructure modeled. the dynamic characteristics of the structure can be analyzed systematically. rapidly and exactly using discrete Fourier transform by means of a computer with small memory.