• ETRI Journal
• /
• v.37 no.3
• /
• pp.617-625
• /
• 2015

In this paper, a steering control system for the path tracking of autonomous vehicles is described. The steering control system consists of a path tracker and primitive driver. The path tracker generates the desired steering angle by using the look-ahead distance, vehicle heading, and a lateral offset. A method for applying an autonomous vehicle to path tracking is an advanced pure pursuit method that can reduce cutting corners, which is a weakness of the pure pursuit method. The steering controller controls the steering actuator to follow the desired steering angle. A servo motor is installed to control the steering handle, and it can transmit the steering force using a belt and pulley. We designed a steering controller that is applied to a proportional integral differential controller. However, because of a dead band, the path tracking performance and stability of autonomous vehicles are reduced. To overcome the dead band, a dead band compensator was developed. As a result of the compensator, the path tracking performance and stability are improved.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.4
• /
• pp.28-35
• /
• 2014

A composite honeycomb core is widely used for lightweight aircraft materials. However, the composite honeycomb core coupled with metal-cutting machining processes does not make a very good match. This paper describes an experimental study of the shape-machining characteristics of a composite honeycomb core, in which a five-axis gantry machine is used. The experimental conditions of the offset allowance, tooling condition and feed rate were applied. The shape machining characteristics of a flat surface, a vertical surface, and a concave surface are evaluated by comparing the machining shape and burr characteristics.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.10a
• /
• pp.123-128
• /
• 2002

The machining parameters for the wire electrical discharge machining(WEDM), including no load voltage, pulse-on time, pulse-off time, wire tension, water flow rata offset etc. should be chosen properly so that a better performance can be obtained An optimum selection of machining parameters relies heavily on the operators technologies and experience. This study presents a method by means of Taguchi method to select optimal machining parameter combination for an cutting speed or surface roughness. Experimental results demonstrate that the machining models are appropriate and the derived machining parameters satisfy the real requirements in notice.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.2
• /
• pp.9-15
• /
• 2011

In order to develop a practical postprocessor for 5-axis machining, the general equations of numerically controlled (NC) data for 5-axis configurations with not only non-orthogonal rotary axes but also orthogonal rotary axes were exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system that suitable for all kinds of 5-axis machine tool with orthogonal and non-orthogonal rotary axes. Through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm is confirmed. Compatibility is improved by allowing exchange of data formats such as rotational tool center position (RTCP) controlled NC data, vector post NC data, and program object file (POF) cutter location (CL)data, and convenience is increased by adding the function of work-piece origin offset. Consequently, the technology of practical post-processor for 5-axis machining is developed.

• Environmental and Resource Economics Review
• /
• v.17 no.3
• /
• pp.61-89
• /
• 2008

In this study, by extending the model proposed by Fullerton and Kim(2006), we explored the tax interdependency effect to examine the relationship between environmental tax and economic growth. The theoretical model shows that environmental tax cannot always stimulate economic growth if other taxes such as labor or income tax are distorted by environmental taxes. However, environmental tax can boost economic growth if cutting distortionary taxes offset the distortion of taxes, or improvement of abatement knowledge can sufficiently reduce the cost of production. An empirical analysis using 14 OECD countries shows a positive relationship between the increase of implicit energy tax rate and the increase of implicit income tax rate. Meanwhile, empirical analysis does not provide enough evidence to claim that the increase of implicit energy tax decreases implicit labor tax. We can presume that environmental tax policy in Europe did not necessarily mitigate the burden of labor tax.

• Journal of Korean Society of Forest Science
• /
• v.100 no.4
• /
• pp.548-557
• /
• 2011

REDD is recognized as a cost-effective and the most appropriate way of managing global GHG emissions. It is negotiated in a global context under the UNFCCC. The main issues of the REDD mechanism are divided into two parts: 1) developing forest carbon verification and measurement system for reducing emissions from deforestation and forest degradation, 2) establishing an appropriate system of incentives for developing countries. REDD can provide stability in carbon offset credits. However, the most important task is to establish a clear legal framework and appropriate governance structures with relevant countries. There is a wide opportunities for Republic of Korea to take a lead in cutting off greenhouse gasses in the Post-Kyoto period.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.2
• /
• pp.301-306
• /
• 2023

Convergeance in the military operations can be attained by simultaneously integrating effects based on sensor, C2, shooter asset in multi-domain and there is no exception to special operations. However, because of challenges from enemy, terrain, geopraphy, and weather, it's not easy to intertwine effects created from ground, sea, air, cyber and electromagnetic spectrum, and space in special operations conducted in deep area. This study presented how to intertwine high-tech such as long-rane reconnaissance·strike drone, cutting-edge sensor, jamming pod, and modular repeater in order to offset aforementioned challenges. Several new high-tech are able to strengthen convergeance of special operations in accordance with the development of the 4th industrial revolution. Therefore, follow-up studies need to be continued making an efforts to search for them.

• Journal of Chest Surgery
• /
• v.32 no.8
• /
• pp.745-748
• /
• 1999

Background: A definitive cure for an essential hyperhidrosis can be obtained by an upper thoracic sympathectomy. However, this is offset by the occurrence of a compensatory hyper hidrosis as a side effect and it is irreversible. We performed a thoracoscopic sympathetic chain block using an endoscopic clip in order to avoid the compensatory hyperhidrosis. Material and Method: From Aug. 1998 to Nov. 1998, 42 cases of thoracoscopic clipping of the T2 sympathetic chain were performed. The sympathetic chain was clipped using an endoscopic clip instead of cutting. Result: Bilateral procedure took less than 40 minutes and occasionally necessitated one night in the hospital. There were no mortality nor life- threatening complications. Horners syndrome occurred in two cases. At the end of postoperative follow-up(median 3 months), 95.0% of the patients were satisfied with the results. Compensatory sweating occurred in 31 cases(77.5%) where nine of those cases were classified as either embarrassing(6 cases-15.0%) or disabling(3 cases-7.5%). Conclusion: Endoscopic thoracic T2 sympathetic chain block using endoscopic clipping is an efficient, safe and minimally invasive surgical method for the treatment of palmar and craniofacial hyperhidrosis and the results were similar to those underwent T2 sympathicotomy. We recommend that patients receive endoscopic sympathetic chain block in summer.

• Journal of Chest Surgery
• /
• v.32 no.2
• /
• pp.171-174
• /
• 1999

Background: Hyperhidrosis of the palms, axillae and face has a strong negative impact on social and professional life. The present existing non-operative therapeutic options seldom give sufficient relief and have a transient effect. A definitive cure can be obtained by upper thoracic sympathectomy. However, this is offset by the occurrence of a high rate of side effects, such as embarrassing compensatory sweating. Material and Method: From Sep. 1997 to Feb. 1998, 89 cases of the needle(2 mm) thoracoscopic thoracic sympathicotomy were performed. The second thoracic ganglion was resected by cutting with a endoscissors. Result: A bilateral procedure takes less than 25 min and requires just one night in hospital. There have been no mortality or life-threatening complications. One patient(<2%) required intercostal drainage because of pneumothorax. Primary failure occurred in one cases(<2%) and recurrent hyperhidrosis occurred in no cases. The patients with failure was successfully re-sympathicotomy. At the end of postoperative follow-up(median 3 months), 96.6% of the patients were satisfied. Compensatory sweating occurred in 57 cases(64.0%) with fourteen of those cases classified as either embarrassing in 10 cases(11.2%) or disabling in 4 cases(4.5%). Conclusion: Endoscopic transthoracic sympathicotomy is an efficient, safe and minimally invasive surgical method for the treatment of palmar and craniofacial hyperhidrosis.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.3
• /
• pp.31-38
• /
• 2019

This study quantified, through a direct harvesting method, storage and annual uptake of carbon from open-grown trees for three landscape tree species frequently planted in the southern region of Korea, and developed quantitative models to easily estimate the carbon reduction by tree growth for each species. The tree species for the study included Camellia japonica, Lagerstroemia indica, and Quercus myrsinaefolia, for which no information on carbon storage and uptake was available. Ten tree individuals for each species (a total of 30 individuals) were sampled considering various stem diameter sizes at given intervals. The study measured biomass for each part of the sample trees to quantify the total carbon storage per tree. Annual carbon uptake per tree was computed by analyzing the radial growth rates of the stem samples at breast height or ground level. Quantitative models were developed using stem diameter as an independent variable to easily calculate storage and annual uptake of carbon per tree for study species. All the quantitative models showed high fitness with $r^2$ values of 0.94-0.98. The storage and annual uptake of carbon from a Q. myrsinaefolia tree with dbh of 10 cm were 24.0 kg and 4.5 kg/yr, respectively. A C. japonica tree and L. indica tree with dg of 10 cm stored 11.2 kg and 8.1 kg of carbon and annually sequestered 2.6 kg and 1.2 kg, respectively. The above-mentioned carbon storage equaled the amount of carbon emitted from the gasoline consumption of about 42 L for Q. myrsinaefolia, 20 L for C. japonica, and 14 L for L. indica. A tree with the diameter size of 10 cm annually offset carbon emissions from gasoline use of approximately 8 L for Q. myrsinaefolia, 5 L for C. japonica, and 2 L for L. indica. The study pioneers in quantifying biomass and carbon reduction for the landscape tree species in the southern region despite difficulties in direct cutting and root digging of the planted trees.