• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.1
• /
• pp.214-221
• /
• 2007

This paper presents a myoelectric hand prosthesis(MHP) with two degree of freedom(2-DOF), which consists of a mechanical hand, a surface myoelectric sensor(SMES) for measuring myoelectric signal, a control system and a charging battery. The actuation for the 2-DOF hand functions such as grasping and wrist rotation was performed by two DC-motors, and controlled by myoelectric signal measured from the residual forearm muscle. The grip force of the MHP was automatically changed by a mechanical automatic speed reducer mounted on the hand. The skin interface of SMES was composed of the electrodes using the SUS440 metal in order to endure a wet condition due to the sweat. The sensor was embedded with a amplifier and a filter circuit for rejecting the offset voltage caused by power line noises. The control system was composed of the grip force sensor, the slip sensor, and the two controllers. The two controllers were made of a RISC-type microprocessor, and its software was executed on a real-time kernel. The control system used Force Sensing Resistors, FSR, as slip pick-ups at the fingertip of a thumb and the grip force information was obtained from a strain-gauge on the lever of the MHP. The experimental results were showed that the proposed control system is feasible for the MHP.

• Journal of Korea Water Resources Association
• /
• v.38 no.6 s.155
• /
• pp.495-504
• /
• 2005

The objective of this study is to estimate the impacts of land cover change on the runoff behavior using Hydrologic Simulation Program-Fortran (HSPF) model and Landsat images. Land cover maps were prepared using three every ten years from 1980 to 2000 of the upper watershed ($258\;km^2$) of Gyeongan stream. Hydrologic parameters of HSPF were calibrated using observed data (1999 - 2000) and validated using observed data (2001, 2003) at Gyeongan gauge station. The simulation results showed that runoff volume and peak rate increased as $15.0\;km^2$ forest areas decreased and $19.3\;km^2$ urban areas increased for 20 years land use changes. The runoff volume showed a higher rate of increase in wet year (2003, 1709.4 mm) than in dry year (2001, 871.2 mm). The peak runoff increased $13.3\;\%$ in normal year (2000, 1257.3 mm) because the year has the highest rain intensity (241.3 mm/hr) among the test years. The runoff volume of a dry season and a wet season (May - September) in normal year 2000 increased $4.4\;\%$ and decreased $8.1\;\%$, respectively.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.10
• /
• pp.106-112
• /
• 1990

The progress of oxidation of a porous silicon layer(PSL) was studied by examining the temperature dependence of the oxidation and the infrared absorption spectra. Thick OPSL(oxidized porous silicon layer). which has the same properties as thermal $SiO_{2}$ of bulk silicon, is formed in a short time by two steps wet oxidation of PSL at $700^{\circ}C$, 1 hr and $1100^{\circ}C$, 1 hr. Etching rate, breakdown strength of the OPSL are strongly dependent on the oxidation temperature, oxidation atmosphere. And its breakdown field was ${1\MV/cm^-2}$ MV/cm The oxide film stress was determined through curvature measurement using a dial gauge. During oxidation at temperature above $1000^{\circ}C$ in dry $O_{2}$, stress on the order of ${10^9}\dyne/{cm^2}{-10^10}\dyne/{cm^2}$ are generated in the OPSL.

• Journal of Information Processing Systems
• /
• v.14 no.4
• /
• pp.1049-1061
• /
• 2018

As mobile devices such as smartphones and tablet PCs become more popular, users are becoming accustomed to consuming a massive amount of multimedia content every day without time or space limitations. From the industry, the need for user satisfaction investigation has consequently emerged. Conventional methods to investigate user satisfaction usually employ user feedback surveys or interviews, which are considered manual, subjective, and inefficient. Therefore, the authors focus on a more objective method of investigating users' brainwaves to measure how much they enjoy their content. Particularly for multimedia content, it is natural that users will be immersed in the played content if they are satisfied with it. In this paper, the authors propose a method of using a portable and dry electroencephalogram (EEG) sensor device to overcome the limitations of the existing conventional methods and to further advance existing EEG-based studies. The proposed method uses a portable EEG sensor device that has a small, dry (i.e., not wet or adhesive), and simple sensor using a single channel, because the authors assume mobile device environments where users consider the features of portability and usability to be important. This paper presents how to measure attention, gauge and compute a score of user's content immersion level after addressing some technical details related to adopting the portable EEG sensor device. Lastly, via an experiment, the authors verified a meaningful correlation between the computed scores and the actual user satisfaction scores.

• Economic and Environmental Geology
• /
• v.34 no.4
• /
• pp.375-383
• /
• 2001

We extracted sea surface heights(SSH) from the TopexJPoseidon(T/P) radar altimeter data to compare with fhe SSH estimated from in-situ lide gauges(T/G) at Ulleungdo, Pohang, and SockcholMucko sites. Selection criteria such as wet/dry troposphere, ionosphere, and ocean tide were used to estimate accurate SSH. For time series analysis, the one-hour interval tide gauge SSHs were resampled al lO-day interval of the satellite SSHs. The ocean tide model applied in the altimeter data processing showed periodic aliasings of 175.5 day, 87.8 day, 62J day, 58.5 day, 49.5 day and 46.0 day, and, hence, the ZOO-day filtering was applied to reduce these spectral noises. Wavenumber correlation analysis was also applied to extract common components between the two SSHs, resulting in enhancing the correlation coefficient(CC) dramatically. The original CCs between the satenite and tide gauge SSHs are 0.46. 0.26, and 0.]5, respectively. Ulleungdo shows the largest cc bec;luase the site is far from the coast resulting in the minimun error in the satellite observations. The CCs were then increased to 0.59, 030, and 0.30, respectively, after 200.day filtering, and to 0.69, 0.63. and 0.59 after removing inversely correlative components using wavenumber correlation analysis. The CCs were greatly increased by 87, 227, and 460% when the wavenumber correlation analysis was followed by 2oo-day filtering, resulting in the final CCs of 0.86, 0.85, 0.84, respectively. It was found that the best SSHs were estimated when the two methods were applied to the original data. The low-pass filtered TIP SSHs were found to be well correlated with the TIG SSHs from tide gauges, and the best correlation results were found when we applied both low-pass filtering and spectral correlation analysis to the original SSHs.

• Journal of Wetlands Research
• /
• v.15 no.2
• /
• pp.223-231
• /
• 2013

Excessive precipitation, drought, heat waves, strong typhoons and rising sea levels are just some of the common indicators of climate change. In the Philippines, excessive precipitation never failed to devastate and drown the streets of Metro Manila, a highly urbanized and flood-prone area; such problems are expected to occur frequently. Moreover, the water supply of Metro Manila is dependent only to Angat Reservoir. Rainwater harvesting can serve as an alternative source of raw water and it can mitigate the effects of flooding. The harvested rainwater can be used for: potable consumption if filtered and disinfected; and non-potable consumptions (e.g., irrigation, flushing toilets, carwash, gardening, etc.) if used untreated. The rainfall data were gathered from all 5 rainfall stations located in Metro Manila namely: Science Garden, Port Area, Polo, Nangka and Napindan rain gauge stations. To be able to determine the potential volume of rainwater harvested and the potentiality of rainwater harvesting system as an alternate source of raw water; in this study, three different climatic conditions were considered, the dry, median and wet rainfall years. The frequent occurrence of cyclonic events in the Philippines brought significant amount of rainwater that causes flooding in the highly urbanized region of Metro Manila. Based from the results of this study, the utilization of rainwater harvesting system can serve as an alternative source of non-potable water for the community; and could also reduce the amount of surface runoff that could result to extreme flooding.

• Restorative Dentistry and Endodontics
• /
• v.30 no.6
• /
• pp.435-441
• /
• 2005

The purpose of this study was to evaluate the effect of increasing application time of single bottle adhesives (SBA) to microtensile bond strength (MTBS) of dried dentin. To expose the superficial dentin surfaces, human molars were sectioned perpendicular to the long axis of tooth. $32\%$ phosphoric acid gels were applied for 15s and rinsed. The teeth were randomly assigned to 3 groups ; S group (Single Bond), O group (One-Step), P group (Prime & Bond NT). Each group was divided to 3 subgroups (W: dentin wipe with wet gauge and light cured immediately, D, dentin dried for 30s and light cured immediately, 30: dentin dried for 30s and light cured after applying SBA for 30s). Composite resin was built up on the dentin surface and sectioned to obtain 20 specimens with $1mm^2$ cross sectional area and the MTBS was measured. For Single Bond, the mean MTBS of S-W and S-30 group were higher than that of S-D group statistically (P<0.05). For One-Step, the mean MTBS of O-D group was statistically lower than that of O-W group (P<0.05). For Prime & Bond NT, the mean MTBS of P-30 group was statistically lower than that of P-D group (P<0.05).

• The Journal of Korean Academy of Prosthodontics
• /
• v.19 no.1
• /
• pp.17-27
• /
• 1981

This study was conducted to determine the chemical composition and the mechanical properties of four commercially available low gold-based crown and bridge alloy produced in Korea. Four dental casting gold-silver-palladium alloys, i.e., A, B, C and D (code of alloys) were selected for the evaluation of chemical composition, ultimate tensile strength, elongation. values and Vickers hardness. The chemical composition of test specimens was analyzed by both emission spectrography and wet gravitation method with a 1.5gm of low gold ingot. The tensile properties and Vickers hardness was determined with cast specimens treated in following three conditions; as-cast, softening heat treatment and hardening heat treatment. The tensile testing bars were cast in accordance with the model designed by Gettleman and Harrison (1969) which was modified from the A. D. A. Specification No. 14 for dental chromium-cobalt casting alloy. Nine tensile test specimens were made from a split silicone mold for each of the test alloys to the size of 2.5mm in diameter and a gauge length of 10mm. All four alloys were handled in accordance with conventional methods used in Type III gold alloys. Ultimate tensile strength and elongation were measured on an Instron Universal Tensile Testing Machine (Model 1125, Japan) operated at a crosshead rate of 0.1cm/min. Elongation values were measured using Digital Measuring Microscope (MS-152, FUSOH, Japan). Vickers hardness was determined with a Vickers Hardness Tester (Model VKH-l, Japan) at a 1.0kg load on a mounted tensile test specimen. The following results were obtained from this study; 1. All tested alloys were composed of Au, Ag, Pd, Cu, Zn and Fe in common. The composition rate of gold for all four alloys was found in the range of $42{\sim}47$ weight % as shown below. Alloy A; Au 45%, Ag 40.2%, Pd 5.76%, others 9.04%. Alloy B; Au 47.1%, Ag 29.03%, Pd 6.98%, others 16.92%. Alloy C; Au 45%, .Ag 26.9%, Pd 6.83%, others 21.07%. Alloy D; Au 41.8%, Ag 34.4%, Pd 6.95%, others 16.85%. 3. The ultimate tensile strength of the four alloys was in the range of $31{\sim}82kg/mm^2$. The test results were shown in the below order from the highest value; As-cast condition; D, B, C, A. Softening heat treament; B, C, D, A. Hardening heat treatment; D, B, C, A. 4. The test :results of the elongation rate for each alloy were in the range of $0.5{\sim}18%$. The test results were shown in the below order from the highest value; As-cast condition; A, D, B, C. Softening heat treatment; A, C, D, B. Hardening heat treatment; C, D, B, A. 5. Vickers hardness for each of the four alloys was in the range of $120{\sim}230$. The test results were shown in the below order from the highest value; As-cast condition; C, B, D, A Softening heat treatment; D, B, C, A. Hardening heat treatment; D, A, C, B. 6. There were no differences in the physical properties between as-cast condition and softening heat treatment.