• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.78-87
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• 2001

The friction and wear behaviors of WC/C multilayer coating were investigated by using a pin on disk type tester. The experiment was conducted by using silicon nitride (S $i_{3}$ $N_{4}$) as a pin material and WC/C multilayer coating on bearing steel (STB2) as a disk material, under various environments that are atmospheric conditions of high vacuum( 1,3$\times$10$^{-4}$ Pa), medium vacuum( 1.3$\times$10$^{-l}$Pa). ambient air( 10$^{5}$ pa)(3 types) and relative humidity(2~98%) conditions. The results showed that WC/C coating fracture was suddenly increased with increasing degree of vacuum, because of high adhesion. So, WC/C coating could not be displayed their ability as solid lubricant. WC/C coating could be displayed better abilitv as solid lubricant with increasing relative humidity. because of oxide film, size and shape of wear debris. The friction coefficient and specific wear rate became better about RH 50%.%.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.3
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• pp.13-23
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• 2020

Currently, online means of replacing resident registration numbers(RRN) include I-Pin, mobile phone, credit card, MyPin, and general-purpose certificate. In order to issue alternative means based on the RRN, it must be designated through the designation review by the Korea Communications Commission(KCC) through a designation review by personal proofing agency and be subject to annual management. However, the criteria for designation and follow-up of the designation of the personal proofing agency carried out by KCC have been used in 2010 without revision, and there are problems that do not conform to the evaluation standards of various alternative means. Therefore, in this paper, we propose a method for improving the designation criteria and management system of the personal proofing service agency. The proposed method analyzes the characteristics of the alternative identification-based personal proofing service and proposes a follow-up management standard that can appropriately evaluate the analyzed characteristics and improves the designation criteria according to the emergence of new alternatives. Through the proposed method, it can be seen that it is possible to strengthen the safety of the personal proofing service based on the alternative means of RRN provided online and face-to-face and to protect the user's personal information.

• Journal of Welding and Joining
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• v.17 no.3
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• pp.90-95
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• 1999

The increase in high speed, multi-function and high I/O pin semiconductor devices highly demands high pin count, very thin, and high density packages. BGA is one of the solutions, but the package has demerits in package reliability, surface mounting problems due to the PCB warpage and solder joint crack related with TCE mismatch between the materials. On this study to verify the thermal fatigue lifetime of the solder joint FEM and experiments were performed after surface mounting BGA with different solder composition and reliability conditions. FEM showed optimum composition of Ag3.2-Sn96.5 and under the composition minimum creep deformation of the solder joint was calculated, and the thermal fatigue lifetime was improved. In view of temperature cycle condition, the conditions of $-65^{\circ}C$to $150^{\circ}C$ showed minimum lifetime and t was 1/3 of $0^{\circ}C$ to $125^{\circ}C$ condition. Test board was prepared and solder joint crack was verified. Until 1000cycle on soder joint crack was observed.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.231-237
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• 2012

This paper introduces a gamma-ray measurement system for a transportable tomography which is applicable for an industrial process diagnosis. The gamma-ray measurement system consists of pulse mode operating 72 channel CsI detectors, main AMP-pulse shaper, single channel analyzer, counter and control PC. The CsI crystal is coupled with a PIN diode which is connected to an amplifier and pulse shaper. For a compact design, the amplifier and pulse shaping circuit are included in a single package. 36 sets of CsI detectors are connected to a multi-channel counter through single channel analyzers. A computer controls and collects data from two multi-channel counters. This configuration results in 72 channel counting system in total. The CT rotator and radiation measurement system are controlled by a PC with LabVIEW program. Tomographic data were measured for a phantom by the measurement system and transportable gamma-ray CT. From the experimental data image reconstructions were performed by ML-EM algorithm. The result showed that the CsI detector system can be a suitable component for transportable gamma-ray CT system.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.427-427
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• 2016

Organic-inorganic hybrid perovskite have attracted significant attention as a new revolutionary light absorber for photovoltaic device due to its remarkable characteristics such as long charge diffusion lengths (100-1000nm), low recombination rate, and high extinction coefficient. Recently, power conversion efficiency of perovskite solar cell is above 20% that is approached to crystalline silicon solar cells. Planar heterojunction perovskite solar cells have simple device structure and can be fabricated low temperature process due to absence of mesoporous scaffold that should be annealed over 500 oC. However, in the planar structure, controlling perovskite film qualities such as crystallinity and coverage is important for high performances. Those controlling methods in one-step deposition have been reported such as adding additive, solvent-engineering, using anti-solvent, for pin-hole free perovskite layer to reduce shunting paths connecting between electron transport layer and hole transport layer. Here, we studied the effect of alkali metal halide to control the fabrication process of perovskite film. During the morphology determination step, alkali metal halides can affect film morphologies by intercalating with PbI2 layer and reducing $CH3NH3PbI3{\cdot}DMF$ intermediate phase resulting in needle shape morphology. As types of alkali metal ions, the diverse grain sizes of film were observed due to different crystallization rate depending on the size of alkali metal ions. The pin-hole free perovskite film was obtained with this method, and the resulting perovskite solar cells showed higher performance as > 10% of power conversion efficiency in large size perovskite solar cell as $5{\times}5cm$. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectrometry (ICP-OES) are analyzed to prove the mechanism of perovskite film formation with alkali metal halides.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.2
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• pp.144-154
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• 2001

Dysfunction of the inferior alveolar nerve indicated by various degree of numbness of the lower lip and chin is one of the few drawbacks of mandibular osteotomy, especially Bilateral Sagittal Split Ramus Osteotomy(BSSRO) and genioplasty. Although it has been recorded throughout the history of this techniques, it is true etiology poorly understood. In this study, 22 consecutive patients under class III malocclusiion impression and undergoing orthognathic surgery(BSSRO only 11 case, BSSRO with genioplasty 11 case) were studied using 4 neurosensory test(static light touch, directional discrimination, two-point discrimination, pin pressure nociception) with post OP 1 week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, 24 weeks, On control group, 10 members without trauma and nerve damage history, nerve test was accomplished. We concluded majority of patients return of sensation during post operative 24 weeks. Althought immediate nerve deficit are 92.2%, 97.2% 88.9% these are recovered to 25%, 35.72%, 10.71% at 24 weeks. Nerve recovery rate increased prominently between post 4 weeks and 8 weeks. There is no statistically difference about neurosensory deficit among the chin area. Neurosensory deficit more severe when the BSSRO with genioplasty group than the only BSSRO group. Immediate neurosensory deficit is larger left side than right side but after 6 months, there is no significantly difference between left side and right side. Static light touch and pin pressure nociception are more sensitive method of neurosensory deficit than two point discrimination.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.2
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• pp.58-66
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• 2012

Brewers grain is a byproduct of beer brewing and consists primarily of grain husks, pericarp, and fragments of endosperm. Although this material is consumed by animals and used as fertilizer, a large amount of brewers grain is simply discarded. Therefore, new methods for utilizing this fibrous resource should be pursued. In this study, we examined the potential utilization of brewers grain as an additive in the paperboard industry by determining the chemical composition of brewers grain and the physical properties of brewers grain powders after grinding with two types of grinders. We found that brewers grain had a lower holocellulose content and higher lignin content and intermediate ash content when compared to other biomass materials, and did not contain any contaminants that would interfere with the papermaking process. Particles had a higher fiber length, less fiber width, and narrower shape factor distribution when ground by a blender type grinder than by a pin crusher type grinder. The blender type grinder was concluded to make regular brewers grain particles appropriate for papermaking.

• The Journal of the Convergence on Culture Technology
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• v.3 no.3
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• pp.27-30
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• 2017

IoT could be applied to various areas because of the important role of sensor. The existing sensor communication method is to quickly transmit data by using clock and two data pins based on the I2C serial communication method. As the objects used are gradually light-weighted and the amount of data transmission is decreased, the simplification of hardware is more emphasized as an essential design element than the speed of transmission. This paper designed a circuit to send/receive data in series, and also realized arduino, by analyzing the existing communication method and then using a single pin for light-weight. The single pin serial communication could reduce power consumption, which is suitable for the sensor area using digital communication of IoT area.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.8
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• pp.45-52
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• 2011

Flash memory is becoming widely prevalent in various area due to high performance, non-volatile features, low power, and robust durability. As price-per-bit is decreased, NAND flash based SSDs (Solid State Disk) have been attracting attention as the next generation storage device, which can replace HDDs (Hard Disk Drive) which have mechanical properties. Especially for the single package SSD, if channel number or FIFO buffer size per channel increases to improve performance, the size of a controller and I/O pin count will increase linearly with channel numbers and form factor will be affected. We propose a novel technique which can minimize form factor by optimizing the number of NAND flash channels and the size of interface FIFO buffer in the SSD. For SSD with 10 channel and double buffer, the experimental results show that buffer block size can be reduced about 73% without performance degradation and total size of a controller can be reduced about 40% because control block per channel and I/O pin count decrease according to decrease channel number.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.197-205
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• 2015

Existing Web authentication method utilizes the resident registration number by credit rating agencies separating i-PIN authentication method which has been improved authentication using resident registration number via the real name confirmation database. By improving the existing authentication method, and it provides the available integrated ID authentication on Web. In order to enhance safety, the proposed authentication method by encrypting the user of the verification value, and stores the unique identifier in the database of the certificate authority. Then, the password required to log in to the Web is for receiving a disposable random from the certificate authority, the user does not need to remember a separate password and receives the random number by using the smart phone. It does not save the user's personal information in the database, and it is easy to management of personal information. Only the integration ID needs to be remembered with random number on every time. It doesn't need to use various IDs and passwords if you use this proposed authentication methods.