Reliable Fault Diagnosis Method Based on An Optimized Deep Belief Network for Gearbox

이철희,Oybek Eraliev,Ozodbek Xakimov,이철희 사단법인 유공압건설기계학회 2023 드라이브·컨트롤 Vol.20 No.4

High and intermittent loading cycles induce fatigue damage to transmission components, resulting in premature gearbox failure. To identify gearbox defects, numerous vibration-based diagnostics techniques, using several artificial intelligence (AI) algorithms, have recently been presented. In this paper, an optimized deep belief network (DBN) model for gearbox problem diagnosis was designed based on time-frequency visual pattern identification. To optimize the hyperparameters of the model, a particle swarm optimization (PSO) approach was integrated into the DBN. The proposed model was tested on two gearbox datasets: a wind turbine gearbox and an experimental gearbox. The optimized DBN model demonstrated strong and robust performance in classification accuracy. In addition, the accuracy of the generated datasets was compared using traditional ML and DL algorithms. Furthermore, the proposed model was evaluated on different partitions of the dataset. The results showed that, even with a small amount of sample data, the optimized DBN model achieved high accuracy in diagnosis

한국노동시장 성격에 대한 비교사적 접근

이철희 서울대학교 경제연구소 2013 서울대학교 경제연구소 학술대회 논문집 Vol.2013 No.2

Design analysis and simulation of an external helical gear

이철희,양진룽,이강희,이철희 사단법인 유공압건설기계학회 2023 드라이브·컨트롤 Vol.20 No.4

This study optimized the parameters of the helical gear based on the original external meshing helical gear pump, combined with the analysis of the stability and flow of the basic parameters of the equipment; herringbone gears were used to eliminate the axial force generated by the helical gears. An optimized helical gear rotor was built with NX. The error between the simulation and calculation results of pump displacement was 3.95% and the simulation results were valid. Analysis of the outlet pressure and lift changes (maximum change rates of 0.38% and 0.25%), pressure analysis of the XY center plane at different times in the same cycle (no pressure surge or drop), and analysis of the axial force of the primary and driven rotors (axis The axial force is close to 0) were performed. The results showed that the flow pulsation of the external gear pump was slight, the operation was smooth, vibration and friction were reduced, the wear of bearings and other components could be diminished, and the service life of the equipment was extended. The simulation results showed that the external gear pump met the design requirements.

기계경비시스템의 서비스 품질, 시스템 성능 및 기업 이미지가 고객 만족도에 미치는 영향

이철희 한국사회안전범죄정보학회 2015 한국범죄정보연구 Vol.1 No.1

이 연구는 우리나라 경비업법에서 규정하는 민간 경비업무인 기계경비시스템의 서비스품질, 시스템성능 및 기업이미지가 고객만족도에 미치는 영향에 관해 살펴본 것이다. 본 연구는 기계경 비시스템의 무인 경비시스템 서비스를 중심으로 고객인 이용자들의 요구가 현시점 얼마만큼 실현 되고 있는지 고객 만족도를 통해 집중적으로 점검해보고 이를 증명하는데 목적이다. 또한 높아진 이용고객의 인식과 커져가는 시장규모에 걸 맞는 질적인 성장유도 및 이용 활성화에 실질적 도움 을 주고자 한다. 이 같은 목적을 수행하고자 고객만족도에 대한 이론과 선행연구의 분석을 통해 민간 경비업의 기계경비시스템 특성을 반영한 적합한 모형을 제시하였으며, 고객만족도에 미치는 요인으로 서비스품질 차원의 요인들과 시스템 성능 및 기업 이미지 차원을 중요요인으로 도출하 고 이들 요인들이 고객만족도에 미치는 영향관계를 분석하였다. 이를 위해 기계경비시스템을 이 용하고 있는 서울과 경기도 소재 중소상점시설(3개 업종)에 대하여 조사한 설문지 자료를 활용하 였다. 전체 400부의 설문지 중 최종 395부를 수거하여 분석에 사용하였으며, 설문지를 통해 수집 된 자료의 통계처리는 SPSS 18.0 통계패키지 프로그램과 AMOS (Analysis of Moment Social Sciences) v. 21.0 프로그램을 사용해 빈도분석, 신뢰도분석, 요인분석, 상관관계분석, 평균비교분 석 및 구조방정식 모형분석을 실시하였다. 이상의 연구절차로 진행된 연구 분석의 결과 서비스품질 요인, 시스템성능 및 기업이미지가 기 계경비시스템의 고객만족도에 영향을 미치는 중요 요인들로 나타났다. 특히 서비스품질 요인 및 시스템성능과 고객만족도 관계에서 기업이미지는 일부 서비스품질 차원의 요인과 시스템성능에 유의미한 매개효과가 있는 것으로 검증되었다. 또한 개인적 특성인 업종과 가입유형, 가입기간이 고객만족도에 미치는 영향 또한 차이가 있는 것으로 나타났다. 따라서 이를 토대로 분석에 있어 인과관계를 설명하고자 분석된 결과와 연구에서 제안한 연구모형이 통계적으로 적합함을 검증하였다. 결론적으로 기계경비시스템이라고 하는 특정한 서비스 이용에 있어서 서비스품질, 시스템 성능 및 기업이미지가 고객만족도에 영향을 미치는 것으로 확인하였다. 그리고 기계경비시스템의 특성상 서비스품질 차원의 구성요인 외에도 시스템성능이 고객만족도에 있어 인과관계가 있음을 확인 하였다. 또 서비스품질과 시스템성능의 고객만족도 간 관계에서 기업이미지가 매개효과가 있음이 확인 되었으며, 고객만족도에 미치는 영향은 직접 또는 간접적인 인과관계가 있는 것으로 나타났 다. 또 기업이미지가 고객만족도에 유의한 영향을 미치는 것으로 확인되었다. This study is to check the influence of service quality, system performance of domestic mechanical security system and the enterprise image on the customer satisfaction. Even though the method of unmanned security of mechanical security system being the physical security is used as the means of crime prevention, etc. it aims to prove this by checking the customer satisfaction intensively if the demand of customers is being realized to some extent at present time. Also, it aimed to have the meaning in presenting the experiential diversity in the practical criminological verification side for the crime prevention. It has the purpose of study for the empirical analysis concerning the actual state check and the customer satisfaction for the whole use of unmanned security method of domestic mechanical security system for this as follows. First, the theoretical content for the mechanical security works according to the domestic security industry act is arranged overall. Second, it analyzes if certain factor affects importantly and has the influence on the use of unmanned mechanical security system. Third, it analyzes how major factors of unmanned mechanical security system influence on the customer satisfaction. The literary consideration of business administration and marketing theory concerning the criminological theory, the satisfaction level and the service concerning the crime prevention in the theoretical basis necessary to investigate the factor of customer satisfaction of unmanned mechanical security system has been carried out to perform the purpose like this. Also, important factors acting on the customer satisfaction have been drawn through the investigation for the preceding research; the research model has been presented to explain the relation between cause and effect in the analysis based on this. The factor of service quality, the system performance and the factor of enterprise image appeared to have the influence on the customer satisfaction of mechanical security system, the fact that the service quality, the system performance, the enterprise image and the individual characteristic have the direct and indirect influence on the customer satisfaction of unmanned mechanical security system have been identified. This aims to distinguish and present factors of customer satisfaction newly based on the characteristic of unmanned mechanical security system besides the component parts of service quality. As the critical point of this study, first, the sampling of population has been restricted to the location of Seoul and Gyeonggi Province, 3 types and patterns of business of users have been presented. Accordingly, there is the limit of study that various desires of users could not be accommodated. Second, there is the limit that various comparisons with the monopoly mode service provision of large enterprise on structure of malformed industry and on characteristic of mechanical security industry have been restrictive. Namely, the width of selection of users may only be extremely limited or restrictive compared to the general product and the service. Third, even though the contractual situation between the customer being the user of unmanned mechanical security system and the supplier shows the individual difference according to the contractual content and the contract period, this cannot be considered sufficiently and there may be the point that it is treated insufficiently. The insufficiency that the action of emotional psychological condition of users for the contractual situation cannot be controlled properly is said to be the limit in the study. Finally, even though the indirect evaluation side aims to be checked at the same time for the crime prevention effect through the empirical investigation and analysis concerning the customer satisfaction of mechanical security system, there is the insufficiency relatively in this side. Finally, the presented research model in the analyzed result and the study through this study has been verified to be suitable statistically. There is the necessity for the attempt willing to access the individual case utilizing the qualitative research method for the use of mechanical security system capable of supplementing this study as seen methodologically more intensively and in-depth to be progressed.

광원의 분광분포 추정에 기초한 관찰 조건에 따른 대응적 색재현

이철희 경운대학교 산업기술연구소 2000 産業技術硏究論文誌 Vol.3 No.1(B)

In this article a corresponding color reproduction algorithm is proposed based on estimation of spectral distribution of chromatic images. For corresponding color reproduction, scene illumination embedded in a chromatic image and adaptation according to viewing conditions have to be calculated. For estimation of scene illumination of a chromatic image, first, the surface spectral reflectances are recovered. In this case, the surface spectral reflectnaces recovered are limited to the maximum achromatic region (NAR) which is the most achromatic and highly bright region of an image after applying intermediate color constancy process using a modified gray world algorithm. Next, the surface reflectances of the maximum achromatic region are estimated using the principal component analysis method along with a set of given Munsell samples. Second, the spectral distribution of reflected lights of MAR is selected from the spectral database. That is, a color difference is compared between the reflected lights of the MAR and the spectral database, which is the set of reflected lights built by the given Munsell samples and a set of illuminants. Then the closest colors from the spectral database are selected. Finally, the illuminant of an image can be calculated dividing the average spectral distributions of reflected lights of MAR by the average surface reflectances of the MAR. For adaptation modeling after estimation of scene illumination, Katoh's mixed chromatic adaptation model was utilized. This method is fundamentally based on a simple von Kries's adaptation model and in addition, takes into account of the human visual system's partial adaptation. In order to evaluate the proposed algorithms, experiments for chromatic images biased by known-lights were performed and visual adaptation experiments for softcopy images on monitor were also simulated under different viewing conditions.

國防費 支出의 經濟成長에 미치는 效果

이철희 陸軍士官學校 1999 한국군사학논집 Vol.55 No.-

The effect of defense expenditures on economic growth has been a controversial issue for long. Recently, the end of cold war has create expectations of a "peace dividend" associated with massive cuts in defense spending. While it is still unclear whether a "dividend" will indeed be paid, most people believe that drastic changes in military spending have a direct and immediate impact on the economy. Despite the importance of such effects, studies on that subject have failed to provide any meaningful consensus on the question of whether defense spending encourages or hinders economic growth. This study tests the effect of defense expenditures on economic growth by using the Korean data form 1973 to 1996. Although the result gives "negative" effect, it is not to represent that defense spending is inefficient. Since defense spending is mainly determined by strategic consideration and threat and security, the effect of defense expenditures should be judged on the basis of the "net effect" of "security effect"and "economic effect."

『바가바드 기타』와 엘리엇의 「드라이 샐베이지즈」 읽기: 『바가바드 기타』의 반영

이철희 한국T.S.엘리엇학회 2016 T.S. 엘리엇 연구 Vol.26 No.1

The objective of this paper is to compare T. S. Eliot’s “The Dry Salvages” with The Bhagavad Gita. Eliot’s interest in The Bhagavad Gita predates his composition of “The Dry Salvages” and accordingly, there are common denominators between the two texts. According to The Bhagavad Gita, Brahman created everything in the world, which is, however, likely to change differently from Brahman. Thus, humans should constantly exert themselves to communicate with Brahman, the center of all things, and in the process, they should give up selfishness and egoism. Both “The Dry Salvages” and The Bhagavad Gita indicate that saints can achieve this difficult goal by getting to the point of intersection of timeless and time. After all, both humans and saints can communicate with Brahman if they make efforts to get rid of private and greedy mind.

抵抗權에 관한 考察

李哲熙 중앙대학교 법학대학 1985 法政論叢 Vol.25 No.-

DSP를 이용한 고속 잡곡 검사 장치의 개발

이철희 경운대학교 산업기술연구소 2002 産業技術硏究論文誌 Vol.5 No.1(B)

컴퓨터 성능의 발달로 다양한 농산물의 품위 판정 분야에 기계 시각 기술을 응용한 실시간 선별 기술이 많이 적용되고 있다. 그러나 잡곡에 대한 품위 판정의 경우 잡곡의 특성상 판별하기 위한 대상입자가 작으며 입자의 기하학적인 구조가 다양하고 또한 다품종으로 인하여 실시간 선별에 많은 어려움이 있다. 따라서 본 연구에서는 실시간 잡곡 선별을 위해 영상의 입력 단계에서 기계적으로 물체와 배경을 분리한 후 문턱치를 응용한 품위 판정을 하여 자유 낙하하는 물체에 대한 실시간 품위판정 시스템을 개발하였다. 고속 처리를 위해 잡곡의 각 채널에 전용 DSP를 이용하여 품위 판정을 하였으며 품위 판정 후 고속 공기 분사기를 이용하여 선별된 곡물을 분리하였다. 개발된 시스템을 대두에 대해 적용한 결과 4채널의 경우 시간당 최대 500kg의 선별량과 85%이상의 판정 결과를 얻었다.

兒童의 基礎體力 發達에 關한 硏究

李哲熙 慶北大學校 師範大學 體育學硏究會 1987 體育學會誌 Vol.15 No.-

This study attempts to test and analyze the physical strength of 300 children who are in the 4th to 6th class of B Primary school in Chinju in oroer to investigate the development of children's basic physical strength. The test of physical strength is carried out as a part of AAU's health test program and the results obtained from the survey are as follows: 1. As they grew older, both boys' and girls' records of Bent-Knee Situps improved gradually. At each age, boys' records of Bent-Knee Situps were 4.98, 8.08, 5.66 times higher than girls'. Compared with the standard of AAU, at the age of 9 to 11, boys' records were -4.02, -1.7, -3.9 times lower than AAU's, with girls' were -6.0, -5.78, -4.56 times lower. 2. Whereas boys' records' records of Sit and Reach showed the maximal improvement by 4.36cm at the age of 10 and 11, girls' records showed the maximal improvement by 7.29cm at the age of 9 to 11 and, particularly, at the age of 10 11, girls' records were higher than boys'. 3. The greatest improvement of boys' record of Pullups was revaled 3.99 times at the age of 10 and 11, but compared with the standard of AAU, it was much the same as AAU's at each age. The records of girls' Flexed Arm Hang were revealed 10.0, 8.5, 12.4 seconds, at each age, higher than the Standard of AAU. 4. Boys' records of Long Jump were 33.44, 15.96, 30.52cm, at each age, higher than the standard of AUU, girls' recorsd were 20.36, 10.56, 23.98cm, at each age, higher than AAU's. 5. Boys' records of Isometric Pushup showed the maximal improvement by 11.90 times at the age of 9 and 10, while girls's record improved gradually as they grew older. For the difference between boys and girls, the records of the former were revealed 8.26, 17.62, 6.17 times, at each age, higher than those of the latter. 6. In the case of Isometric Lec Squart, as boys and girls grew older, their records are both improved gradually but there was little difference in the record of both sexes. 7. Boys' records of Shuttle Run, as they grew older, improved gradually, while girls' records were about the same as boys'. As for the difference between boys' and girls' records, boys' records were higher than girls', but compared with the standard of AAU, their records were both much same. 8. Boys' records of 50-yard Sprint, at each age, were 4.07, 3.43, 3.65 seconds higher than the standard of AAU, girls' records were lower at the age of 10 and 11.