• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.107-112
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• 2014

The productivity and cost of clear cutting operations were examined to broaden our knowledge on the harvesting system in a Larix leptolepis stand of Korea. The harvesting system was divided into tree operations which were chainsaw (STIHL MS440) felling, tower yarder (Koller301-4) yarding and harvester (WOODY H50) processing. The average cycle time of felling, yarding and processing were 98 s/cycle, 245 s/cycle and 150 s/cycle. The total stump-to-pile operational productivity was 43.07 $m^3/hr$. The highest production activity was the felling 17.93 $m^3/hr$, followed by the productivity of processing 15.62 $m^3/hr$ and then by the productivity of yarding 9.52 $m^3/hr$. In addition the total stump-to-pile operational cost was 24,086 $won/m^3$. The highest cost activity was the yarding 14,557 $won/m^3$ (60.4% of the total cost), followed by the costs of processing 8,461 $won/m^3$ (35.2%) and then by the costs of felling 1,068 $won/m^3$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.420-425
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• 2012

Lead-free piezoelectric ceramic/epoxy composites with '0-3' connectivity were prepared by cold-pressing with a temperature controlled curing method. A ceramic powder with a composition of $(Na_{0.51}K_{0.47}Li_{0.02})(Nb_{0.8}Ta_{0.2})O_3$ was synthesized by a conventional solid state reaction route. The dielectric and piezoelectric properties of ceramic/epoxy composites were characterized as a function of the volume fraction (${\phi}$) of piezoelectric ceramics, which was varied from 70 to 95 vol%. The results indicated that the piezoelectric properties of composites were significantly affected by the volume fraction of ceramics. In terms of the piezoelectric properties, specimens showed the best performance at ${\phi}$= 85 vol%, resulting in the piezoelectric constant $d_{33}$ of 39 pC/N and the figure of merit as a piezoelectric energy harvester ($d_{33}{\cdot}g_{33}$) of 1.24 $pm^2/N$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.73-78
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• 2005

Demand for the domestic hairy vetch seed production will be increased with the increasing interest of environment-friendly agriculture in Korea. This study was conducted during from 2000 fall to 2003 spring at upland field of National Institute of Crop Science in Suwon, Korea to compare wheat and triticale (TC) as stake crop of hairy vetch (HV), and to know proper seeding rates and ratios between TC and HV for the maximum HV seed production. As supporting crop of HV, TC was superior to wheat at the points of higher HV seed yield, stronger TC stalk for supporting, consistence of ripening stage of two seeds. In seeding method, row seeding was superior to broadcast seeding at the points of less lodging and higher HV seed yield. HV seed yield decreased with the increase of TC seeding rate in mixture cropping (row seeding), particularly at TC seeding rates over 5kg/10a. HV seed yield increased with the increase of HV seeding rate at the condition of TC seeding rates under 5kg/10a in spite of higher lodging of mixed crops at higher HV seeding rate due to higher HV aboveground dry matter. Maximum HV seed yield was obtained at TC seeding rate of $1\~1.5kg/10a$ as indicating HV seed yield 176kg/l0a (CV. Madison) at seeding rate of TC 1kg/10a + HV 2 kg/10a in 2001, and HV seed yield 96kg/10a (CV. Common) at seeding rate of TC 1.5kg/10a + HV 4.5kg/10a in 2003. Use of all-purpose combine harvester for harvesting and appliance for separation of mixed seeds using centrifugal force, which are prerequisite for HV seed production, was excellent in the simultaneous seeds production system of HV and TC.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.287-294
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• 2000

Calculation of the flexural rigidity value (EI) is indispensable for prescription of deflection characteristics of crop stalks in harvesting□Conventionally□EI has been determined by either average EI of the whole stalk or average EI of each stems divided into node through the calculation method of cantilever with homogeneous section□However□deflection characteristics of crop stalks caused by mechanical operation such as combine harvester were not exactly presumed by these conventional EI through the experiment by authors. Further, actual EI of a stalk changes in company with a change of moisture contents as time passes during the experiment. Finally, efficient calculation method for determining EI is needed in order to improve these problems. In this study, mechanical model based on actual structure of the crop stalk with variety sectional area was proposed. This mechanical model is calculated by the theory of cantilever with continuous stages. Therefore, improvement of both calculating accuracy on EI and efficiency of measuring system was tried. At first, this calculation method was applied to piano wire of which EI was recognized in advance. As a result, EI calculated from this new method coincided approximately with piano wire's EI. Next, applying to crop stalks as same as piano wire, relationship between loads acting on crop stalks and deflection values calculated by EI using this new calculation method was exactly presumed in comparison with conventional method. Further, measuring time of deflection test was greatly reduced. Finally, new calculation method of EI will be available for estimating mechanical characteristics of so many kinds of crop stalks in harvesting operation. Further, in this study, new deflection test using image-processing apparatus by computer will be introduced.

• Agricultural and Biosystems Engineering
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• v.6 no.2
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• pp.47-53
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• 2005

AMachine vision is a promising tool for the autonomous guidance of farm machinery. Conventional CCD camera for the machine vision needs a desktop PC to install a frame grabber, however, a web camera is ready to use when plugged in the USB port. A web camera with a notebook PC can replace existing camera system. Autonomous steering control system of this research was intended to be used for combine harvester. If the web camera can recognize cut/uncut edge of crop, which will be the reference for steering control, then the position of the machine can be determined in terms of lateral offset and heading angle. In this research, a white line was used as a cut/uncut edge of crop for steering control. Image processing algorithm including capturing image in the web camera was developed to determine the desired travel path. An experimental vehicle was constructed to evaluate the system performance. Since the vehicle adopted differential drive steering mechanism, it is steered by the difference of rotation speed between left and right wheels. According to the position of vehicle, the steering algorithm was developed as well. Evaluation tests showed that the experimental vehicle could travel within an RMS error of 0.8cm along the desired path at the ground speed of $9\sim41cm/s$. Even when the vehicle started with initial offsets or tilted heading angle, it could move quickly to track the desired path after traveling $1.52\sim3.5m$. For turning section, i.e., the curved path with curvature of 3 m, the vehicle completed its turning securely.

• Journal of Biosystems Engineering
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• v.26 no.4
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• pp.323-330
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• 2001

The regular maintenance and repair status of major farm machinery such as power tiller, farm tractor, rice transplanter and combine harvester etc., were surveyed and analyzed for the full-time farmers in order to get basic information for promoting farm machinery productivity. The survey was carried out through 209 farmers from 9 provinces. The results of this study can be summarized as follows; 1. The regular maintenance of farm machinery was conducted at repair shop(49.5%) or dealer agency(12.0%), and also conducted by farmers at their house(34.9%). 2. For the status on the cleanness or exchange times of engine oil, fuel filter and air cleaner, most farmers conducted fewer times than the necessary times. And, 5.3%, 7.7%, and 2.9% of surveyed farmers experienced breakdowns due to the insufficient cleanness or exchange oil, fuel filer, and air cleaner, respectively. 3. Most farmers(76.1%) recognized the necessity of farm machinery training or education, and they preferred one week for the training period, simple or easy maintenance for the training level, agricultural technical center or farm machinery manufacturer for the training agency. 4. Complete recognition of operation manual and sufficient maintenance before-, during-, and after-operation for the farm machinery can minimize the breakdowns, enlarge the endurance prevent the safety accidents, and promote productivity of farm machinery. And, these can be accomplished by the thorough training or education for agricultural machinery.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.153-162
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• 2018

The importance of energy harvesting technique is increasing due to the elevated level of demand for sustainable power sources for wearable device applications. In this study, we developed an Energy Harvesting wearable Platform(EH-P) architecture which is used in the design of a multi-energy source based on TENG. The proposed switching circuit produces power with higher current at lower voltage from energy harvesting sources with lower current at higher voltage. This can powers microcontrollers for a short period of time by using PV and TENG complementarily placed under hard conditions for the sources such as indoors. As a result, the whole interface circuit is completely self-powered with this makes it possible to run of sensing on a Wearable device platform. It was possible to increase the wearable device life time by supplying more than 29% of the power consumption to wearable devices. The results presented in this paper show the potential of multi-energy harvesting platform for use in wearable harvesting applications, provide a means of choosing the energy harvesting source.

• Smart Structures and Systems
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• v.16 no.3
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• pp.383-399
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• 2015

Today, as railways increase their capacity and speeds, it is more important than ever to be completely aware of the state of vehicles fleet's condition to ensure the highest quality and safety standards, as well as being able to maintain the costs as low as possible. Operation of a modern, dynamic and efficient railway demands a real time, accurate and reliable evaluation of the infrastructure assets, including signal networks and diagnostic systems able to acquire functional parameters. In the conventional system, measurement data are reliably collected using coaxial wires for communication between sensors and the repository. As sensors grow in size, the cost of the monitoring system can grow. Recently, auto-powered wireless sensor has been considered as an alternative tool for economical and accurate realization of structural health monitoring system, being provided by the following essential features: on-board micro-processor, sensing capability, wireless communication, auto-powered battery, and low cost. In this work, an original harvester device is designed to supply wireless sensor system battery using train bogie energy. Piezoelectric materials have in here considered due to their established ability to directly convert applied strain energy into usable electric energy and their relatively simple modelling into an integrated system. The mechanical and electrical properties of the system are studied according to the project specifications. The numerical formulation is implemented with in-house code using commercial software tool and then experimentally validated through a proof of concept setup using an excitation signal by a real application scenario.

• Composites Research
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• v.28 no.6
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• pp.383-388
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• 2015

Ionic Polymer-Metal Composite (IPMC) consisting of soft membrane plated by platinum electrode layers on both surfaces generates electric energy when subjected to various mechanical stimuli. The paper proposes a circuit model that describes the physical composition of IPMC to predict the voltage generation characteristic corresponding to bending motion. The parameter values in the model are identified to minimize the RMS error between the real and simulated outputs. Following the design of IPMC circuit model, the state observer of the model is designed by using pole placement technique which improves the model accuracy. State observer design technique is also applied to find the inverse model which estimates the input bending angles from the output voltage data. The results show that the inverse model estimates input bending angles fairly well enough for the further applications of IPMC not only as an energy harvester but also as a bending sensor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.257-258
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• 2015

Korean power consumption of the electrical supply problems due to excess demand is repeated every year, the interest in energy increasing social and personal cost has been subject to the number of ways to reduce this cost increases. Automatic doors and automatic door installation market is increasing every year and frequently, when used in general commercial and communal porch consumption based on average 300 times a day power is 70[W] degree is a monthly average usage is about 50.4[KW]. The level can not ignore the power consumption due to switching frequency is large. In this paper, by converting the energy to be discarded in the automatic doors to the inverter and the regenerative energy and to develop control systems for power regeneration to reduce the power consumption by utilizing automatic contact auxiliary power.