• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.37-45
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• 2010

Since SRC (Short-term Rotation Coppice) such as poplar and willow can be harvested in three years, they are known to be a potential forest biomass as fuel for a power plant. The production system including transplanting and harvesting is, however, necessary to be mechanized because such a biomass should be handled in a massive volumetric size. A pull-type stem-cutting transplanter was developed in the research as the first step to realize the production of SRC. A needle-like transplanting device pushes a stem-cutting into the prepared soil bed by a pneumatic cylinder, and another device firms soil around a stem-cutting transplanted. Since this is an intermittent operation, it was necessary to develop a zero horizontal velocity mechanism which enabled only the transplanting needle part to continue a zero horizontal movement relative to the ground during the transplanting operation even when the tractor kept moving forward. The 2-row transplanter can transplant stem-cuttings at the rate of 6.5 seconds per row without missing a single attempt. The planting depth and distance were well maintained and controlled. Their CVs were between 2.1~3.4% and 0.87~1.7% for the depth and the distance, respectively. Although, the transplanted stem-cuttings tended to lean outward from the back-view and forward from the side view, they were planted within the range of $3^{\circ}$ from the upright position.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.10-15
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• 2015

A thin-film transmission line (TFTL) employing a microstrip line/coplanar waveguide (ML/CPW) was fabricated on a silicon substrate for application to a miniaturized on-chip RF component, and the RF characteristics of the device with the proposed structure were investigated. The TFTL employing a ML/CPW composite structure exhibited a shorter wavelength than that of a conventional coplanar waveguide and that of a thin-film microstrip line. When the TFTL with the proposed structure was fabricated to have a length of ${\lambda}/8$, it showed a loss of less than 1.12 dB at up to 30 GHz. The improvement in the periodic capacitance of the TFTL caused for the propagation constant, ${\beta}$, and the effective permittivity, ${\varepsilon}_{eff}$, to have values higher than those of a device with only a conventional coplanar waveguide and a thin film microstrip line. The TFTL with the proposed structure showed a ${\beta}$ of 0.53~2.96 rad/mm and an ${\varepsilon}_{eff}$ of 22.3~25.3 when operating from 5 to 30 GHz. A highly miniaturized impedance transformer was fabricated on a silicon substrate using the proposed TFTL for application to a low-impedance transformation for broadband. The size of the impedance transformer was 0.01 mm2, which is only 1.04% of the size of a transformer fabricated using a conventional coplanar waveguide on a silicon substrate. The impedance transformer showed excellent RF performance for broadband.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.1-8
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• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.197-198
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• 2006

In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general material. In this study, some kinds of polyamide-6 powders with different shape and particlesize were fabricated to investigate the formability, the microstructure and mechanical properties. Also, to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing fe lens used in commercial SLS. Polyamide-6 powders having the average size of 100 m were treated thermally in order to keep the spherical symmetry in shape. These polyamide-6 powders were mixed with polyamide-12 powders having the average size of 50 m to give the bimodal distribution of size. These mixed powders showed the better fabrication in the selective laser sintering process because the smaller particles of polyamide-11 played an important role in the compact packing of powders by filling the void space between the large particles of polyamide-6. Also, Experiments have performed to evaluate the effect of a scanning path and sintering parameters by fabricating the various 3D objects.

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.171-173
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• 1993

UV-ray air cleaner consisted of 6 watt UV lamp and fan was developed to sanitize air of refrigerator. Light intensity of the lamp showed 5 times of D value of Bacillus subtilis and air velocity around the lamp in holding section was 0.7 m/s, giving 0.33s of the resident time. The performance of air cleaner was tested with bacterial contaminator sprayed with suspension of Bacillus subtilis and hey powder. The device effectively decreased 80% of the population of airborn spore after 100 min operation at room temperature.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.87-93
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• 2011

This paper proposes a method for extraction of the gaze point on display using EOG(Electrooculography) signal. Based on the linear property of EOG signal, the proposed method corrects scaling difference, rotation difference and origin difference between coordinate of using EOG signal and coordinate on display, without adjustment using the head movement. The performance of the proposed method was evaluated by measuring the difference between extracted gaze point and displayed circle point on the monitor with 1680*1050 resolution. Experimental results show that the average distance errors at the gaze points are 3%(56pixel) on x-axis, 4%(47pixel) on y-axis, respectively. This method can be used to human computer interface of pointing device for general paralysis patients or HCI for VR game application.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.15-19
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• 2003

In This paper, we developed 1.96 GHz air gap type FBAR BPF using ZnO as piezoelectric sputtered by RF magnetron at room temperature. FBAR BPF was fabricated by sputtering bottom electrode (Al), ZnO as piezoelectric and top electrode (Mo) on Si wafer one by one with RF magnetron sputter, then Si was dry etched to make an air hole. XRD test result of fabricated FBAR BPF showed that ZnO crystal was well pre-oriented as (002) and sigma value of XRC was 1.018. IL(Insertion loss) showed excellent result as 1 dB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.219-222
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• 2003

In this paper, we designed a Ku-band BPF(Band Pass Filter) by microstrip line that most usually used a microwave device design and fabrication. Here a substrate of designed BPF were silicon substrate(${\varepsilon}_r=11.8$), and metal line was copper and silver/copper structure. And a configration of BPF was used hairpin pattern. A center frequency of designed BPF was 10GHz and their FBW(Fractional Band Width) was 20%(2GHz). It presented simulated results obtained for a 10GHz filter which yields an insertion loss of 0.1dB that ripple value related chebyshev reponse. Finallt we tried to make that a 30dB attenuation frequency was 20% of center frequency.

• ETRI Journal
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• v.24 no.2
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• pp.109-116
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• 2002

We propose a novel very short (< $300{\mu}m$) vertical directional coupler switch with high extinction ratios larger than 30 dB. The device consists of a switching operation induced section (SOIS), an extinction ratio adjusted section (ERAS), and an extinction ratio enhanced section (ERES). These are achieved by changing the refractive index of one core. The switching operation is induced by changing the refractive index of one core in the SOIS. The improvement of extinction ratios larger than 30 dB for both the cross and bar states is made by controlling the asymmetry of the refractive indices of both cores in the ERES. Through the ERAS, different extinction ratios between the cross and bar states at the end of the SOIS are changed to the same value. For this reason, the optimum asymmetry of the refractive indices of the cores for the maximum extinction ratios and the lengths of ERES are the same for cross and bar states. Design guidelines for high extinction ratios with large tolerances are presented.

• Journal of Sensor Science and Technology
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• v.28 no.4
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• pp.205-215
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• 2019

A flexible polyvinylidene fluoride (PVDF)/polydimethylsiloxane (PDMS) composite prototype with high piezoelectricity and force sensitivity was constructed, and its huge potential for applications such as biomechanical energy harvesting, self-powered health monitoring system, and pressure sensors was proved. The crystallization, piezoelectric, and electrical properties of the composites were characterized using an X-ray diffraction (XRD) experiment and customized experimental setups. The composite can sustain up to 100% strain, which is a huge improvement over monolithic PVDF fibers and other PVDF-based composites in the literature. The Young's modulus is 1.64 MPa, which is closely matched with the flexibility of the human skin, and shows the possibility for integrating PVDF/PDMS composites into wearable devices and implantable medical devices. The $300{\mu}m$ thick composite has a 14% volume fraction of PVDF fibers and produces high piezoelectricity with piezoelectric charge constants $d_{31}=19pC/N$ and $d_{33}=34pC/N$, and piezoelectric voltage constants $g_{31}=33.9mV/N$ and $g_{33}=61.2mV/N$. Under a 10 Hz actuation, the output voltage was measured at 190 mVpp, which is the largest output signal generated from a PVDF fiber-based prototype.