• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.656-660
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• 2008

This study is carried out to minimize the damage to the forest road when locating strip roads in the future for stability of timberland after afforestation by assessing the factors that affect the damage on the forest road surface and making appropriate constructing standards. Major factors that influence damage to the strip road surface were location, longitudinal gradients, soil types, cross-section shape in order of influence on damage. it is considered that structural road factors like longitudinal gradients, road width, location factors such as construction location, slope gradients and road material like soil types were greatly related to occurrence of road surface damage. Damage occurrences in the forest road were severe at the valley, longitudinal gradients of over 24%, weathered granite soil, concave of road position, road width of over 3.0 m. stability was high at longitudinal gradients of 4~24%, road width of under 3.0 m, ridge of road position, straight slope, soil materials. The evaluation table of damage possibility on forest road was manufactured by discriminant analysis using Quantification theory(II). The results showed that the discriminant ratios was 79.4% and this table was available for forest manager.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.3
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• pp.55-71
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• 2019

The purpose of this study is to propose an evaluation method to assess green environments of streetscapes to improve urban street green spaces in Jeonju City. Through a rapid assessment of urban street green spaces, we suggest an objective basis for expanding street green space as well as for adopting sustainable maintenance and improvement measures. We choose 12 sections of streetscapes (roads and sidewalks) to investigate existing street conditions which have more than four lanes and function as major road axes. Six large roads and six medium roads of Jeonju City center area are investigated as pilot assessment study sites. Site inventory checklists consist of environmental characteristics of streetscape, street tree status, and planting condition evaluation. Environmental characteristics of streetscapes are composed of physical and neighborhood factors. For instance, items for physical factors are types and width of road/sidewalks, paving materials, tree protection materials, and green strip. And surrounding landuse is a neighborhood factor. Assessment items for street tree status are street plant names (tree/shrubs/ground cover), size, and planting intervals. Planting condition evaluation items are tree shape, damage, canopy density, and planting types with existence of adjacent green space. Evaluation results are classified into three levels such as A(maintain or repair), B(greening enhancement), and C(structural improvement). In case of grade A, streetscapes have enough sidewalk width for maintaining green strip and a multi-layered planting(in large road only) with fairly good growing conditions of street trees. For grade B and C, streetscapes have a moderate level of sidewalk width with a single street tree planting. In addition, street tree growing conditions are appeared poor so that green enhancement or maintenance measures are needed. For median, only grade B and C are found as its planting growing foundations are very limited in space. As a result, acquiring enough sidewalk space is essential to enhance ecological quality of urban street green. Especially, it is necessary to have green strip with reasonable widths for plant growing conditions in sidewalks. In addition, we need to consider native species with multi-layer plant compositions while designing street green.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1937-1941
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• 2004

We present lateral actuated piezoelectric actuator using U-shaped PZT strip and lever structure for the RF switch application. In the previous study of RF switch, they used horizontal contact switch fabricated by thin film metals. However, thin film metals could not generate large contact force due to low stiffness. In this work, we suggest lateral contact switch which makes large contact force by increasing stiffness. In addition, we use PZT actuator for the high force actuation. Generally actuator using thin film PZT moves to the vertical direction due to the neutral axis shift. Therefore we need lateral motion generation mechanism based on the thin film PZT actuator. In order to increase lateral motion of thin film PZT actuator, we use U-shaped PZT actuator using residual stress control. Also, thin film PZT actuator can generate very small lateral motion of 120${\times}$10$^{-6}$ ${\mu}{\textrm}{m}$/V for d$_{31}$ mode, thus we suggest lever structure to increase stroke amplification. From the experimental study, fabricated PZT actuator shows maximum lateral displacement of 1 ${\mu}{\textrm}{m}$, and break down voltage of the thin film PZT actuator is above 16V.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.18-24
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• 2003

The resonator using two layer microstrip structure was proposed and the bandpass filter was designed using this resonator in this paper. The proposed resonator structure is constructed by placing a U-shape of resonator in the first layer and then placing a broadside coupling strip in the second layer just above of the U-shape of resonator's edge part. Because these structure has various design parameters than general single layer coupled line structure, filter design is more flexible. In this paper, the narrow band filter was designed using multi-layer structure that had been applied to broadband filter because it's high coupling nature. The filter was designed to have 4MHz center frequency and 3 % fractional bandwidth, and finally confirmed that can be realizable narrow band filter by using multi-layer structure through fabrication and measurement.

• Transactions of Materials Processing
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• v.7 no.3
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• pp.246-259
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• 1998

This paper describes a research work of developing a computer-aided design and manufacturing of irregular shaped sheet metal product for blanking or piercing and bending operations. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts, This system has been written in AutoLISp on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules which are input and shape treatment, flat pattern-layout, pro-processor module. Based on the knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product complexities of blank geometry and punch profile sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing and bending die in this field.

• Corrosion Science and Technology
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• v.10 no.1
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• pp.1-5
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• 2011

The major purpose of the present study is to evaluate the performance of various galvanized (GI) or galvannealed (GA) mild steels and AHSS in stamping applications. Finite Element Analysis (FEA) of selected stamping operations was conducted to estimate the critical pressure boundary conditions that exist in practice. Using this information, laboratory tribotests, e.g. Twist Compression (TCT), Deep Drawing (DDT) and Strip Drawing (SDT) Tests, were developed to evaluate the performance of selected lubricants and die materials/coatings in forming galvanized steels of interest. The sheet materials investigated included mild steels and AHSS (e.g. DP600 GI/GA, DP780 GI/GA, TRIP780 GA and DP980 GI/GA). Experimental results showed that galvanized material resulted in more galling, while galvannealed material showed more powdering and flaking. The surface roughness and chemical composition of galvanized sheet materials affected the severity of galling under the same testing conditions, i.e. lubricants and die materials/coatings. The results of this study helped to determine the critical interface pressure that initiates lubricant failure and galling in stamping selected galvanized sheet materials. Thus, to prevent or postpone the critical interface conditions, the results of this study can be used to select the optimum combination of galvanized sheet, die material, die coating and lubricant for forming structural automotive components.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.66-72
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• 2008

During the plate and foil cold rolling process, considerable values of the force of material pressure on the tool occur. These pressures cause the elastic deformation of the roll, thus changing the shape of the deformation legion. Rolled copper foils should be characterized by a good quality and light dimensional tolerances. Because of automation that is commonly implemented in flat product rolling mills, these products should meet the requirements of tightened tolerances, particularly strip thickness, and feature the greatest possible flatness. The shape of the roll gap is influenced by the elastic deformation of rolls parts of the rolling process affecter of the pressure force. However, to control roll deformation should be difficult. Because the foil thickness is very thin and the permissible deviations in the thickness of foil are small. In this paper, FE-simulation of roll deformation in thin foil cold roiling process is presented.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.331-340
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• 1994

Polysilicon on insulator has been recrystallized by zone melting recrystallization method with graphite strip heaters. Experiments are performed with non-seed SOI structures. When the capping layer thickness of Si$\_$3/N$\_$4//SiO$\_$2/ is 2.0.mu.m, grain boundaries are about 120.mu.m spacing and protrusions reduced. After the seed SOI films are annealed at 1100.deg. C in NH$\_$3/ ambient for 3 hours, the recrystallized silicon surface has convex shape. After ZMR process, the tensile stress is 2.49*10$\^$9/dyn/cm$\^$2/ and 3.74*10$\^$9/dyn/cm$\^$2/ in the seed edge and seed center regions. The phenomenon of convex shape and tensile stress difference are completely eliminated by using the PSG/SiO$\_$2/ capping layer. The characterization of SOI films are showed that the SOI films are improved in wetting properties. N channel SOI MOSFET has been fabricated to investigate the electrical characteristics of the recrystallized SOI films. In the 0.7.mu.m thickness SOI MOSFET, kink effects due to the floating substrate occur and the electron mobility was calculated from the measured g$\_$m/ characteristics, which is about 589cm$\^$2//V.s. The recrystallized SOI films are shown to be a good single crystal silicon.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.188-193
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• 1996

This study was performed the blankholding force and vee-ring effects on Blanking characteristics, such as maximum blanking force, burnish, dish-shape, hardness. etc, in fine-blanking die by the experimental method. Two types of aluminum (Al. 1050-0, Al 5052-H) Such as annealed and unannealed materials were used for the experiment. In order to get a hydrostatic pressure effect, the clearance was set to 0.5% of the thickness of strip, and the counter punch and stripper plate with Vee-ring was set-up. While this experiment was carrying out, the average blanking Velocity was constant (37.5mm/sec) As a result of this study, we got a good surface roughness and a glassy shear plane(burnish) of the sheet over 90% thickness, and such as the excellent accuracy of dimensions, the good squareness and the reduction of dish-shape could be obtained, and also the additional results obtained were such that the hardness of shear plane was increased and the maximum blanking force was reduced in the condition of Vee-ring height of 1.0~1.5mm, and blankholding force of 1200kg.

• Structural Engineering and Mechanics
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• v.47 no.1
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• pp.75-98
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• 2013

This study focuses on shear strengthening performance of simply supported reinforced concrete (RC) T-beams bonded by glass fibre reinforced polymer (GFRP) strips in different configuration, orientations and transverse steel reinforcement in different spacing. Eighteen RC T-beams of 2.5 m span are tested. Nine beams are used as control beam. The stirrups are provided in three different spacing such as without stirrups and with stirrups at a spacing of 200 mm and 300 mm. Another nine beams are used as strengthened beams. GFRP strips are bonded in shear zone in U-shape and side shape with two types of orientation of the strip at $45^{\circ}$ and $90^{\circ}$ to the longitudinal axis of the beam for each type of stirrup spacing. The experimental result indicates that the beam strengthened with GFRP strips at $45^{\circ}$ orientation to the longitudinal axis of the beam are much more effective than $90^{\circ}$ orientation. Also as transverse steel increases, the effectiveness of the GFRP strips decreases.