• Journal of Biosystems Engineering
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• v.26 no.1
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• pp.29-38
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• 2001

A navigation system was developed for autonomous guidance of a combine. It consisted of a DGPS, a machine vision system, a gyro sensor and an ultrasonic sensor. For an autonomous operation of the combine, target points were determined at first. Secondly, heading angle and offset were calculated by comparing current positions obtained from the DGPS with the target points. Thirdly, the fuzzy controller decided steering angle by the fuzzy inference that took 3 inputs of heading angle, offset and distance to the bank around the rice field. Finally, the hydraulic system was actuated for the combine steering. In the case of the misbehavior of the DGPS, the machine vision system found the desired travel path. In this way, the combine traveled straight paths to the traget point and then turned to the next target point. The gyro sensor was used to check the turning angle. The autonomous combine traveled within 31.11cm deviation(RMS) on the straight paths and harvested up to 96% of the whole rice field. The field experiments proved a possibility of autonomous harvesting. Improvement of the DGPS accuracy should be studied further by compensation variations of combines attitude due to unevenness of the rice field.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.45-52
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• 2016

One commercial package for magnetic analysis was used to apply repulsive forces of permanent magnetics to bicycle cushion system. Reliabilities of finite element analysis were acquired by comparing with those of experimental measurements. Equivalent spring stiffnesses corresponding to various sizes of magnetics were implemented into the bicycle dynamic model with three degree of freedom. Input force caused at front and rear wheels due to road unevenness was considered in the dynamic model. Dynamic behaviors were observed in terms of vertical displacements of the rider and the front reach as well as pitching displacement of the mass center when the bicycle ran over half-triangular bump. The methodology suggested in this paper by the finite element analysis and numerical model will be an useful tool for more accurate prediction of cushion design for any vehicle system if magnetic forces are utilized.

• Polymer(Korea)
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• v.31 no.3
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• pp.228-232
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• 2007

This purpose of this study is to enhance the hydrolysis of poly (butylene succinate-co-L-lactate) (PBSL) and poly [(R) -3-hydroxybutylate] (PHB), to develop materials with advanced medical absorbability and environmental suitability. The first method involves increasing the bioabsorbability of poly (glycolic acid) (PGA) in the core of the fibrous complex, while the second method involves making a complex fiber containing PBSL and PHB in the outer layer for improving environmental degradability Improvement in the hydrolysis of PBSL and PHB due to glycolic acid occurs by hydrolytic behavior of PGA. The drawing supporting the resulting PBSL/PGA fiber was executed at $65^{\circ}C$, where the orientation is well arranged in crystal form. Obtaining a PHB/PGA complex fiber in the proper crystal orientation at $50^{\circ}C$ was not possible since the arranged crystal orientation was only identified in drawings from temperatures above $50^{\circ}C$. Also, it is necessary to execute a smooth surface to achieve an on-line drawing since unevenness occurs in the fibrous surface from an in-line drawing.

• Journal of Conservation Science
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• v.33 no.1
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• pp.43-49
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• 2017

The ancient paper document we chose as a case study for our research is "One Hundred Poets of the Tang Dynasty", which is housed in the Ryukoku University Library. The purpose of this research is to introduce a method to analyze the surface roughness and microstructure at a high resolution. In addition, we attempt to quantitatively measure the surface unevenness of the types and curve structure. We used a tridimensional digital microscopy as a non-contact and a non-destructive method to study ancient cultural paper. The information contained in the paper may be lost in the process of applying strong pressure to clean and lining or press. However, this microscopic measurement method can non-destructively analyze a large amount of data in old printed books. Moreover, it enables observing them directly with reflected light. Therefore, this method may be useful for collecting printed information remaining on the surface of the paper.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.34-39
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• 2010

Due to big demand for satellite and communication service using personal handheld terminals, demand for satellites with huge antennas is increasing correspondingly. While such large antennas are realized by various types of deployable antennas, the reflecting surface is made by many facets irrespective of deploying mechanisms. In order to analyze the faceted-reflector more accurately, an existing ray-tracing method is improved. The algorithm allows the rays to cross each other, which is the main characteristic of the faceted-reflector, and takes unevenness of amplitude and phase over the aperture plane into consideration. For the study of the effect of facet configuration, facet generating algorithm is devised. From the analysis algorithm and the facet-generating algorithm, it has been found that the number of facets in a radial direction affects both directivity and sidelobe level. On the other hand, the number of facets in a circumferential direction affects sidelobe level only.

• Journal of Adhesion and Interface
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• v.8 no.3
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• pp.16-23
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• 2007

Polyester fabrics and knits were corona treated with different current intensity (5, 10, 15, 20 A) and feeding speed (5, 10, 15 m/min). We confirmed the surface change of polyester fabrics and knits using scanning electron microscopy (SEM) and X-ray photoelectron spectrometer (XPS). And the change of physical properties through measuring the tensile strength, dry and wet bonding strength. Thermosetting reactive polyurethane hot melt adhesive was used in the adhesion of polyester fabrics and knits. Functional groups were introduced on PET fabrics and knits surface by treating the PET fabrics and knits in air atmosphere with corona discharge, and take placed unevenness, the result adhesion was improved. When consider both dry and wet bonding strength, we think that appropriate conditions in the PET fabrics corona treatment are feeding speed 10 m/min, current intensity 15 A and appropriate conditions in the mesh type PET knits corona treatment are feeding speed 10 m/min, current intensity above 10 A.

• Korean Journal of Environment and Ecology
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• v.21 no.1
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• pp.74-81
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• 2007

This study investigated the growth pattern and species composition by landform and seaside distribution to evaluate the basic community structure and topographical distribution of the Peucedanum japonicum Thunb. community group in Korea. The appearing plants with the Peucedanum japonicum Thunb. were a total 170 taxa belonging to 130 genera and to 57 families, and the species number by families was the most in Compositae of 30 taxa. The frequency of appearing plants was the highest in the Aster spathulifolius Max.(54.1%), and the east and west seasides were the highest in the Aster spathulifolius Max. and south seaside was the highest in the Miscanthus sinensis Ander.. The ratio of common plants among seasides was the highest between the west and south seasides of 35.6% with 47 taxa. The distribution landforms of the Peucedanum japonicum Thunb. was a $17.4^{\circ}$ slope of the unevenness landform, vertical joint, horizontal joint, blockfield, planation surfaces and the rocky seaside of the sea cliff. The distribution among landforms was the greatest in the rocky seaside of the 61 regions. The sociability on growing pattern was the highest in the 3 sociability rank of 54.6% with the 83 region.

• Journal of the Korean housing association
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• v.18 no.5
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• pp.1-10
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• 2007

This study is to analyze the residential spatial composition structures of vernacular agricultural village which to be called Wanggok in Yeongdong area. The results of this study are as follows; ${\cdot}$ The backyard of farmhouses is surrounded by a fence and a frontyard is open to the road, so that the spatial realm system from the road to the backyard is classified as public-semi public-private realm. ${\cdot}$ The plan type of this village is mainly composed of ㅡ type Gyeobjib (the two row rooms under one roof) and ㄱ type Gyeobjib, the Anmaru (the inner wood floor to be surrounded with wall) in both of which plays an important role that connects Sarangbang (the men's main room) with Anbang (the women's main room) in the residential space. ${\cdot}$ The particular item that not found out in another area is the Sarangbang kitchen which located to Sarangbang's side wall to be furnished with a fire hole. ${\cdot}$ The houses represent the socio-cultural environmental elements of those built days, such as while Sarangbang is faced on a frontyard to be open to the neighborhood, Anbang is faced on a backyard surrounded with a fence to be closed to the one. ${\cdot}$ The Gyeobjib with Anmaru appeared by cultural transformation connecting the 田-shaped house of Hamgyeongdo with the Gyeobjib with Anmaru of Gangwondo and Gyeongsangbukdo. ${\cdot}$ The ㄱ type Gyeobjib is preferred to ㅡ type Gyeobjib because of the sea wind and the north-east wind occurring by geographical and climatic environment elements, the privacy protection according to look into a frontyard, the muck drainage of cowshed to make use of ground unevenness, the economic gains called material saving and the intention to enlarge the frontyard as to be concentrated in a residential space and etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.204-207
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• 2003

This paper presents the electrical properties of PTFE (polytetrafluoroethylene) nozzle for circuit breaker. PTFE has been used widely as a nozzle material for circuit breaker. In the arcing environment in a circuit breaker, radiation is considered to be the major energy transport mechanism from the arc to the wall. The fraction of the radiation power is emitted out of the arc and reaches the nozzle wall, causing ablation at the surface and in the depth of the wall. The energy concentration in the material lead to the depolymerization and eventually lead to the generation of decomposed gas as well as some isolated carbon particles. The generation of the decomposed gas in the depth of the material causes inner explosion. The surface of nozzle becomes uneven. The flow of gas is not uniform due to the unevenness of the surface. Adding some fillers into PTFE is expected to be efficient for improving the endurability against radiation. In this experiment, three kinds of fillers that have endurance in the high temperature environment were added into PTFE. Dielectric constant, dissipation factor, electrical resistivity and dielectric strength of PTFE composites were investigated.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.369-375
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• 2020

FDM 3D printing structures have rough surfaces and require post-treatment to improve the properties. Fumigation is a representative technique for removing surface unevenness. Surface treatment by fumigation proceeds by dissolving the surface of the protruding structure using a vaporized solvent. In this study, 3D printed PVB outputs are surface-treated with ethyl-alcohol fumigation. As the fumigation time increases, the surface flattens as ethanol dissolves the mountains on the surface of PVB and the surface valleys are filled with dissolved PVB. Through the fumigation process, the mechanical strength tends to decrease, and deformation rate increases. Ethanol vapor permeates into PVB, widening the distance between chains and resulting in weak bonding strength between chains. In order to confirm the effect of fumigation only, an annealing process is performed at 80 ℃ for 1, 5, 10, 30, and 50 minutes and the results of the fumigation are compared.