Contactless Transfer of Conductive Rod Using an Electrodynamic Wheel

정광석,원광민 한국정밀공학회 2011 International Journal of Precision Engineering and Vol.12 No.4

A novel electrodynamic wheel is proposed to convey a conductive rod. When rotating the spiral electrodynamic wheel around the conductive rod, a radial force and an axial force are generated, and are used to convey the rod without mechanical contact. However, even though the radial force acting on the rod is a repulsive force, the spatial stability of the rod is not always guaranteed in the uncontrolled mode. The stability depends fully on the operating condition. So, for the proposed conveyance system, the operating conditions for dynamic stability of the rod are clarified on the basis of dynamic analysis and finite element analysis (FEA) with experimental verification, thereby showing the feasibility of the proposed conveyance system. A test setup is designed and used to analyze the effect of the relative position between permanent magnets (PMs) constituting the wheel, and the pole number of PMs.

자기 부상 방식 미세 운동 기구의 동적 모델링

정광석,백윤수,Jeong, Gwang-Seok,Baek, Yun-Su 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.5

In this paper, we introduce a positioner based on magnetic levitation to eliminate the friction which is the most severe effect to limit high resolution on the micro level. Differently from existing electromagnetic device, the proposed positioner consists of air core solenoid and permanent magnet. Although the combination produces small magnetic force, it is suitable for realizing micro motion repeatedly without the accumulation of error because there is no hysteresis caused by ferromagnetic materials, no eddy current loss, no flux saturation. First, the approximate modeling of stiffness and damping effects between the magnetic elements is made and verified experimentally. Then, we have formulated the dynamic equation of one d.o.f magnetic levitation positioner using linear perturbation method and discussed the necessity of optimization for the chief design parameters to maximize the stability performance.

Impact of Summer Rainfall on the Seasonal Water Quality Variation (Chlorophyll a) in the Regulated Nakdong River

정광석,김동균,신현석,윤주덕,김현우,주기재 대한토목학회 2011 KSCE Journal of Civil Engineering Vol.15 No.6

In this study, the relationship between hydrological characteristics and phytoplankton biomass (chlorophyll a concentration) was explored using long-term hydrological and limnological data (1994-2007) in a flow-regulated river system (the lower Nakdong River, South Korea). This river has four multi-purpose dams and an estuarine barrage, and river flow is extensively controlled. Dynamics of chlorophyll a concentration responded well to changes in hydrology, such as rainfall, dam discharge and river flow. The hydrological characteristics strongly affected the decrease of chlorophyll a concentration in summer to winter but not in spring (p<0.05; n=42). An application of Self-Organizing Map (SOM) model to the database returned three clusters, and strong seasonality in water quality as well as hydrological characteristics was identified. Long-term rainfall data exhibited no statistical tendencies of increase or decrease, with respect to total annual rainfall. In comparison, summer rainfall increased while that of winter (December to the following February) decreased. Summer rainfall affected total dam discharges in all seasons in a positive manner (p<0.05; n=14),corresponding to winter water quality of the lower Nakdong River likely to be dependent largely upon changes in summer rainfall. Therefore, the development of an effective management strategy for summer rainfall and dam discharge control is strongly required.

다상 전류 중첩을 이용한 기어비 가변 마그네틱 기어의 토크 조절

정광석 한국생산제조학회 2019 한국생산제조학회지 Vol.28 No.6

By controlling the speed of one layer of a concentric magnetic gear, we can change the ratio of the rotational speed between the other two layers, which are composed of permanent magnets and ferromagnetic steel. This results in torque ratio between the layers that is not the inverse of the speed, unlike in a general speed reducer. The value of the torque ratio is determined from the pole ratio of the permanent magnets and steel teeth constituting the layers. In this study, we propose experimentally verified method of varying the torque of the output layer of a variable speed magnetic gear by superimposing another polyphase power source on the control coil. By setting the torque ratio inversely to the speed, constant power can be maintained and some of the coil's power can be supplied to the output side.

DC 편의된 다상 입력을 이용한 횡자속 선형 유도 전동기의 부상/추진 독립 제어

정광석,백윤수,허진혁 대한기계학회 2004 大韓機械學會論文集A Vol.28 No.11

비선형 시계열 하천생태모형 개발과정 중 시간지연단계와 입력변수, 모형 예측성 간 관계평가

정광석,김동균,윤주덕,라긍환,김현우,주기재,Jeong, Kwang-Seuk,Kim, Dong-Kyun,Yoon, Ju-Duk,La, Geung-Hwan,Kim, Hyun-Woo,Joo, Gea-Jae 한국하천호수학회 2010 생태와 환경 Vol.43 No.1

In this study, we implemented an experimental approach of ecological model development in order to emphasize the importance of input variable selection with respect to time-delayed arrangement between input and output variables. Time-series modeling requires relevant input variable selection for the prediction of a specific output variable (e.g. density of a species). Inadequate variable utility for input often causes increase of model construction time and low efficiency of developed model when applied to real world representation. Therefore, for future prediction, researchers have to decide number of time-delay (e.g. months, weeks or days; t-n) to predict a certain phenomenon at current time t. We prepared a total of 3,900 equation models produced by Time-Series Optimized Genetic Programming (TSOGP) algorithm, for the prediction of monthly averaged density of a potamic phytoplankton species Stephanodiscus hantzschii, considering future prediction from 0- (no future prediction) to 12-months ahead (interval by 1 month; 300 equations per each month-delay). From the investigation of model structure, input variable selectivity was obviously affected by the time-delay arrangement, and the model predictability was related with the type of input variables. From the results, we can conclude that, although Machine Learning (ML) algorithms which have popularly been used in Ecological Informatics (EI) provide high performance in future prediction of ecological entities, the efficiency of models would be lowered unless relevant input variables are selectively used.

전자기력 조합에 기초한 평면 구동기를 이용한 자기 부상 방식 초정밀 스테이지

정광석,백윤수,Jeong, Gwang-Seok,Baek, Yun-Su 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.11

In this Paper, we suggest the precision stage using a novel non-contact planar actuator that utilizes an interaction between an array type of air-core solenoids and permanent magnets. The former with axes arranged in the mutually orthogonal direction is fixed on the stator and the latter with the same polar direction is attached below the stage. The promising magnetic structure has little uncertainty such as hysteresis loss caused by ferromagnetic material, then it is simple to quantify the magnetic phenomenon. And all the magnetic forces are transmitted through narrow air-gap between the coil and the permanent magnet, therefore the structure can be highly compacted. Furthermore, the stage or plate can be perfectly isolated from the stator without any wire connection, leading to diminish the generating possibility of wear particles due to mechanical contact. Then. it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness. or general-purpose nano stage. The main issues rebated to the plate driving are discussed here.

조절강 생태계인 낙동강에서 식물플랑크톤 동태의 예측 및 패턴분석을 위한 Machine Learning Modelling의 적용

정광석 부산대학교 2004 부산대학교 박사학위논문 Vol.0 No.-

자기 포커싱 방법을 적용한 감속 장치의 자기력 특성에 관한 연구

정광석,Jung, Kwangsuk 한국교통대학교 융복합기술연구소 2021 융ㆍ복합기술연구소 논문집 Vol.11 No.1

The magnetic gear, which amplifies the torque by filtering the magnetic field generated by the low-speed permanent magnet with a modulator, can exclude gear contact and can be effectively applied when there are environmental restrictions. In this paper, we discuss the magnetic force characteristics of a magnetic gear using a magnetic focusing array that replaces a general permanent magnet array magnetized in a radial direction along the circumferential direction. The torque increasing effect of the discussed array, known as an arrangement that increases the principal component by focusing a radial magnetic field, is compared with that of a general magnetic gear. In particular, in a magnetic gear using such an array, the sensitivity of torque according to variables is analyzed to see how various variables known as factors affecting torque have an effect.

초음파 중합에 의한 polypyrrole 나노입자를 함유하는 메조포러스 TiO₂ 박막의 합성

정광석,조성호,송명근,김종득,Jang, Kwang-Suk,Cho, Sung-Ho,Song, Myung-Geun,Kim, Jong-Duk 한국화학공학회 2008 Korean Chemical Engineering Research(HWAHAK KONGHA Vol. No.

Using ultrasonic-induced polymerization of pyrrole, mesoporous $TiO_2$ thin film with polypyrrole nanoparticles was prepared. Polypyrrole nanoparticles were ultrasonically synthesized in the mother solution of mesoporous $TiO_2$ before spin-coating. The polypyrrole particles were well dispersed in the solution. After spin-coating and calcinations process, the nanocomposite films have well-organized pore channels without pore-collapse, and polypyrrole nanoparticles are well dispersed in mesoporous $TiO_2$ matrix. The pore size and light absorbance of the mesoporous nanocomposite thin films were controlled by using different template materials, and by using different amount of pyrrole monomer, respectively. 초음파 중합법을 이용하여 pyrrole을 중합시킴으로써 polypyrrole 나노입자를 합유하는 메조포러스 $TiO_2$ 박막을 합성하였다. 메조포러스 $TiO_2$ 박막을 만들기 위한 $TiCl_4$-계면활성제 용액에 pyrrole을 넣어주고 초음파 중합시킴으로써 용액 내에 polypyrrole 나노입자들이 잘 분산된 형태로 만들어졌다. 이 용액을 이용하여 spin-coating과 열처리를 함으로써 polypyrrole 나노입자를 합유하는 메조포러스 $TiO_2$ 박막을 제조하였다. 열처리 후에도 기공 구조는 잘 유지되었으며, polypyrrole 나노입자들이 박막 내에 잘 분산되었다. 주형물질인 계면활성제의 종류와 pyrrole의 양을 조절함으로써, 합성된 박막의 기공 크기와 빛의 흡광도를 조절하였다.