• Composites Research
• /
• v.32 no.6
• /
• pp.314-318
• /
• 2019

A simple and very flexible automatic dipping machine was constructed for producing functional multilayer films on wide substrates via the layer-by-layer (LbL) assembly technique. The proposed machine exhibits several features that allow a fully automated coating operation, such as various depositing recipes, control of the dipping depth and time, operating speed, and rinsing flow, air-assist drying nozzles, and an operation display. The machine uniformly dips a substrate into aqueous mixtures containing complementary (e.g., oppositely charged, capable of hydrogen bonding, or capable of covalent bonding) species. Between the dipping of each species, the sample is spray cleaned with deionized water and blow-dried with air. The dipping, rinsing, and drying areas and times are adjustable by a computer program. Graphene-based thin films up to ten-bilayers were prepared and characterized. This film exhibits the highly filled multilayer structures and low thermal resistance, indicating that the robotic dipping system is simple to produce functional thin film coatings with a variety of different layers.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.8
• /
• pp.17-27
• /
• 2017

Gangwon province which is located in northeast of Korea is the coldest region where average daily temperature is below zero during winter while the other regions are above zero. However, there have been insufficient researches on the insulation design and the effect of the insulation on the freezing damages, even though freezing damages were reported consistently in the lining of road tunnel during winter. In this study, to investigate the effect of insulations on the reduction of freezing damages, numerical analysis was performed considering geotechnical and meteorological characteristics in Gangwon province during winter. As a result, it was found that thickness of concrete and shotcrete in lining had negligible effect on the freezing depth while the insulation had significant effect on it. In addition, because the freezing depth is greatly affected by the thermal conductivity of the ground behind the lining in the period of cold weather, these effects should be considered in the estimation of the insulation thickness.

• Journal of Sensor Science and Technology
• /
• v.5 no.1
• /
• pp.63-70
• /
• 1996

Silicon epitaxial films of submicron level were successfully grown by the RTCVD method. For the growth of silicon epitaxial layers, $SiH_{2}Cl_{2}\;/\;H_{2}$ gas mixtures and various process parameters including $H_{2}$ prebake process were used. The growth conditions were varied to investigate their effects on the interface abruptness of doping profile, the film growth rates and crystalline properties. The crystallinity of the undoped silicon was excellent at the growth temperature of $900^{\circ}C$. The doping profiles were measured by SIMS technique. The abruptness of doping profile would be controlled within about $200{\AA}/decade$ in the structure of undoped Si / $n^{+}-Si$ substrate.

• Korean Journal of Optics and Photonics
• /
• v.13 no.6
• /
• pp.461-466
• /
• 2002

Fiber-optic comb filters using a side-polished fiber coupler are proposed as multi-channel isolation filters on wavelength division multiplexing systems. We have demonstrated that the coupling efficiency between two waveguides is improved by the intermediate coupling layer in spite of the decrease of the optical power transfer between two waveguides due to the high-order modes of the overlay waveguide coupled with the side-polished single-mode fiber. When LiNbO$_3$with a 200-${\mu}{\textrm}{m}$-thickness was applied as a planar-overlay-waveguide, the comb filtering characteristics with a 4 nm-channel-spacing were achieved and the maximum power coupling occurred at the 1-${\mu}{\textrm}{m}$-thickness and the refractive index in range 1.52 to 1.53 of an intermediate coupling layer. If the intermediate coupling layer is optimized, an extinction ratio with more than 20 dB can be obtained. These experimental results are in good agreement with the BPM simulation.

• Polymer(Korea)
• /
• v.33 no.3
• /
• pp.268-271
• /
• 2009

In this study, the distribution behaviors of the polystyrene sulfonic acid (PSSA) grafting polymer across the FEP-g-PSSA membranes prepared by a simultaneous irradiation method, were investigated by analyzing the cross-section of the membranes with a SEM-EDX instrument. The effects of irradiation conditions such as the degree of grafting, FEP film thickness, and grafting solvent on the distribution of the grafting polymer were mainly studied in this experiment. The results indicate that to obtain the evenly grafted FEP-g-PSSA membranes, the higher degree of grafting is required as the film thickness increases, and the lower dose rate are more effective than the higher dose rate at the given dose.

• Composites Research
• /
• v.33 no.2
• /
• pp.55-60
• /
• 2020

A study on the heating behavior and adhesion property of structural epoxy adhesive through induction heating have been conducted. An adhesive for induction heating was manufactured through mixing with nano and micro sized Fe₃O₄. From the results, it was observed that induction heating is less affected by adherend (GFRP) thickness than oven heating. The heating rate of Fe₃O₄ embedded epoxy adhesive using induction heating much higher than that of oven curing process and it is more appreciable when the contents of Fe₃O₄ increased. Furthermore, adhesion strength increased with increase of Fe₃O₄ particle contents.

• Journal of the Korean Ceramic Society
• /
• v.39 no.4
• /
• pp.377-385
• /
• 2002

The possibility of $ZrO_2$ thin film as insulator for Metal-Ferroelectric-Insulator-Semiconductor(MFIS) structure was investgated. $SrBi_2Ta_2O_9$ and $SrBi_2Ta_2O_9$(SBT) thin films were deposited on P-type Si(111) wafer by R. F. magnetron sputtering method. The electrical properties of MFIS gate were relatively improved by inserting the $ZrO_2$ buffer layer. The window memory increased from 0.5 to 2.2V in the applied gate voltage range of 3-9V when the thickness of SBT film increased from 160 to 220nm with 20nm thick $ZrO_2$. The maximum value of window memory is 2.2V in Pt/SBT(160nm)/$ZrO_2$(20nm)/Si structure with the optimum thickness of $ZrO_2$. These memory windows are sufficient for practical application of NDRO-FRAM operating at low voltage.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.14 no.4
• /
• pp.506-511
• /
• 2004

Biometrics is getting more and more attention in recent years for security and other concerns. So far, only fingerprint recognition has seen limited success for on-line security check, since other biometrics verification and identification systems require more complicated and expensive acquisition interfaces and recognition processes. Hand-Geometry has been used for biometric verification and identification because of its acquisition convenience and good performance for verification and identification performance. Hence, it can be a good candidate for online checks. Therefore, this paper proposes a Hand-Geometry recognition system based on geometrical features of hand. From anatomical point of view, human hand can be characterized by its length, width, thickness, geometrical composition, shapes of the palm, and shape and geometry of the fingers. This paper proposes thirty relevant features for a Hand-Geometry recognition system. However, during experimentation, it was discovered that length measured from the tip of the finger was not a reliable feature. Hence, we propose a new technique based on Genetic Algorithm for extraction of the center of nail bottom, in order to use it for the length feature.

• Journal of Sasang Constitutional Medicine
• /
• v.11 no.2
• /
• pp.195-207
• /
• 1999

1. PURPOSE This research is a study on constitutional diagnosis through the external appearances, and for finding shape differences of the hand and foot according to the Sasang Constitution. 2. Method We collected 148 person who were healthy and measured length, breadth, circumference and thickness of their hands and feet with 'The Measurement of R. Martin'. We analyzed shape differences of hand and foot according to the Sasang Constitution and made a certain conclusion. 3. Results and Conclusions We got the morphologic characteristics of hand and foot according to the Sasang Constitution. (1) The physical characteristics. The weight is heaviest in Taeumin. (2) The morphologic characteristics of Hand. (1) The wrist circumference is longest in Taeumin. (2) The finger length / hand length(ratio) is higher Soeumin than Taeumin. (3) The wrist breadth is largest in Taeumin(only male). (4) The wrist breadth is larger Taeumin than Soeumin(only female). (5) The palm length is longer Taeumin than Soyangin(only male). (6) The maximum hand breadth is larger Taeumin than Soeumi (only male). (7) The 2nd, 3rd and 4th finger length is longer Soeumin than Soyangin(only male). (3) The morphologic characteristics of Foot. (1) The foot thickness is thickest in Taeumin. (2) The foot breadth is largest in Taeumin. (3) The ankle circumference is longest in Taeumin(only male).

• Journal of Embryo Transfer
• /
• v.18 no.3
• /
• pp.249-255
• /
• 2003

These studies were performed to improve the reproductive efficiency of gilts and we investigated the effects of puberty periods, first mating time and backfat thickness and will adapt to these results for early selection of excellent gilts. The main results were as follows; 1. First heats on birth season were showed 194.14 day, 163.25 day, 160.25 day and 157.92 day at birth of spring, summer, autumn and winter, respectively and birth of spring was significantly latest among other seasons (p<0.01). 2. First service on birth season were revealed 222.05 day in spring, 193.00 day in summer, 199.20 day in autumn and 190.11 day in winter. birth of spring was significantly latest among others (p<0.01). 3. First heat period of cadidated gilt had 13∼16 mm backfat thickness was 180.32 day, 171.24 day in 17∼20 mm and 162.20 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 4. First service of cadidate gilt had 13∼16mm backfat thickness was 211.12 day, 202.43 day in 17∼20 mm and 195.43 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 5. The litter size were 9.64 in gilts under 160 day of first heat, 10.14 in 161∼180 day, 9.56 in 181∼200 day and 9.13 in over 201 day. There showed the largest litter size in 161∼180 day of first heat but was no differences. 6. The litter size in gilts under 180 day of first service was 9.13, 9.75 in 181∼200 day, 10.13 in 201∼220 day and 9.45 in over 221 day. There showed the largest litter size in 201∼220 day of first service but was no differences. 7. The litter size of gilt had 13∼16 mm backfat thickness on first service was 9.33, 9.81 in 17∼20 mm and 10.17 in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness.