• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.26.1-26.1
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• 2009

A simple route of external mechanical force is presented for enhancing the electrical properties of polymer nanocomposite consisted of nanowires. By dispersing ZnO nanowires in polymer solution and drop casting on substrates, nanocomposite transistors containing ZnO nanowires are successfully fabricated. Even though the ZnO nanowires density is properly controlled for device fabrication, as-cast device doesn't show any detectable currents, because nanowires are separated far from each other with the insulating polymer matrix intervening between them. Compared to the device pressed at 300 kPa, the device pressed at 600 kPa currents increased by 50times showing the linear behavior against drain voltage and exhibits promising electrical properties, which operates in the depletion mode with higher mobility and on-current. Such an improved device performance would be realized by the contacts improvement and the increase of the number of electrical path induced by external force. This approach provides a viable solution for serious contact resistance problem of nanocomposite materials and promises for future manufacturing of high-performance devices.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.9
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• pp.614-619
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• 2010

Recently, a problem related to the thermal management in portable electronic and telecommunication devices is becoming issued. That is due to the trend of a slimness of the devices, so it is not easy to find the optimal thermal management solution for the devices. From now on, a pressed circular type cooling device has been mainly used, however the cooling device with thin thickness is becoming needed by the inner space constraint of the applications. In the present study, the silicon flat plate type cooling device with the separated vapor and liquid flow path was designed and fabricated. The normal isothermal characteristics created by vapor-liquid phase change was confirmed through the experimental study. The cooling device with 70 mm of total length showed 6.8 W of the heat transfer rate within the range of $4{\sim}5^{\circ}C/W$ of thermal resistance. In the future, it will be possible to develop the commercialized cooling device by revising the fabrication process and enhancing the thermal performance of the silicon and glass cooling device.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.272-284
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• 1992

As a preliminary step toward the development of a multipurpose electrostatic separator for agricultural use, this study investigated the effect of moisture level, geometrical characteristics and the electric field strength of a charging device on the electrostatic charging of brown rice, unhulled paddy, small stones and broken rice that are produced during the milling process. The results are summarized as follows. 1. Average electrostatic charge per unit mass of paddy is greater than that of brown rice. 2. Charge per unit mass of rice kernel increases linearly with moisture content and electric field strength of the charging device, presenting no correlations with length or thickness of rice kernel. 3. Frequency distributions in electrostatic charge per unit mass of paddy and brown rice kernels indicated that the portion, not overlapped, ranged from 10 to 29% with Japonica rice and from 32 to 49% with Indica rice. 4. The difference in moisture content between paddy and brown rice must be over 6%, if they are to be electrostatically separated to over 95%. 5. Theoretical portions of brown rice to be separated from a mixture primarily by the electrostatic charge and secondarily by the length or by the thickness were 95~100% and 27~76%, respectively. 6. Frequency distribution of electrostatic charge for broken kernels overlapped that of paddy and brown rice, which the small stones didn't.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.23-26
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• 2014

This paper represents the detection method of voltage disturbance for high temperature superconducting (HTS) tape using electromagnetically coupled coils. In order to detect the voltage as the superconductor transits from the superconducting state to the normal conduction state, voltage taps are widely used to get the voltage signal. And voltage taps are connected to data acquisition device via signal wires. However this new suggested method can detect the superconducting transition voltage without signal wires between voltage taps and data acquisition device by using electromagnetically coupled coils. This system consists of two electromagnetically coupled coils, the first coil to detect and transmit the voltage of HTS tape and the second coil to pick up the transmitted voltage from the first coil. By using this new suggested method, we can build the 'separated voltage-detection system'. HTS tape and first coil are located under liquid nitrogen vessel and the second coil is located under room temperature condition. In this paper, experiments are performed to verify the feasibility of the proposed method. As the result of the experiment, the separated voltage-detection system using electromagnetically coupled coils can successfully observe superconducting-normal transition of HTS tapes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.257-261
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• 1993

This paper presents a design method of turning device for robotic assembly based on the verification of a instability for a base assembly. To derive the instability, first we inference collision free assembly directions by extracting separable directions for the part, and calculate the separability which gives informations as to how the part can be dasily separated. Using the result, we determine the instability evaluated by summing the all separabilites of each component part in base assembly. The proposed method gives a design guidance of turning device by evaluating a degree of the motion istability for the base assembly in flexible manufacturing application. An example is given to illustrate the concepts and procedure of the proposed scheme.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.542-545
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• 1995

This paper provides an investigation of torque converter system using ERF (Electro-Rheological Fluid). The torque converter system using ERP is a new concepting device because we can change an apparent viscosity of ERF by adapting an electric field. The device was designed by using the equations which were proposed by Carlson et al. The devices based on ERF generally assume one two possible forms. One is the parallel plate type in which the device elements are facing circular disks separated by a flat layer of ERF, The other is coaxial cylinder or Couette types in which the ERF file the annular apace between a pair of coaxial cylindrical electrode. The discussion on this study is specifically for coaxial cylinder gemetry and experiment results show that the measured torque was rapidly increased with the increase of the eletric field.

• Quality Improvement in Health Care
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• v.23 no.1
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• pp.55-67
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• 2017

Purpose:The purpose of this study was to apply the disinfection method using chlorhexidine in practice on disinfection of vascular access for hemodialysis. Methods: This study was designed as a randomized controlled trial for examining effectiveness on infection of the vascular access device for hemodialysis when using chlorhexidine and betadine/alcohol. One-hundred-thirty study participants were separated into two groups randomly. Infection signs of the vascular access device for hemodialysis were observed and recorded before disinfection on vascular access device. Result: Before the study, there was no difference between the experimental group (chlorhexidine group) and the control group (betadine/alcohol group) in general characteristics and hematological index. Incidence of infection rate of chlorhexidine group was 0 percent and the betadine/alcohol group was 1.5 percent. There was no significant difference between the two groups. Conclusion: This study examined the effectiveness of prevention of infection with the disinfection method using chlorhexidine and betadine/alcohol. The disinfection method using chlorhexidine is considered an effective and alternative method of betadine/alcohol.

• The Korean Journal of Health Service Management
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• v.7 no.3
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• pp.203-212
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• 2013

Medical devices separated by a committee of the International Electrotechnical Commission IEC TC (Technical Committee) 62 medical electrical equipment being promoted by the International standards. Actually, a lot of standards were existed, but many national and international standards for medical devices were lacking in practical standards that can be applied to their development. Most international standards were focused in electrical and mechanical safety of medical devices. Therefore, there were few practical standards which contain essential performance evaluation. Although medical device regulations do not enforce a fixed lifecycle model, activities are presented in a sequential manner, thus hinting at a waterfall process. Meanwhile, for a decade or more, software teams have benefitted from agile development methods. Several medical device manufacturers have adopted agile practices while keeping development in compliance with regulations, but conflicts arise and decisions have to be taken in favor of agility or formality. However, if there are new practical standards of medical devices, it must be possible to promote the medical devices industry in their nation. To do this, there is a need to develop a new standard could apply to the international market through the analysis of the medical device related technology. Consequently, new standards such as NP (New proposal) or NWIP (New Work Item Proposal) should be developed through international standardization of medical device technology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.840-843
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• 2002

The dry pulverizing/Mixing device is used to deal with the spent fuels for the safe disposal. The separated pellets from hulls by a slitting device are put and oxidized from UO$_2$ solid pellet to U$_3$O$\_$8/ powder in the device. The device have been developed based on a voloxidation method which is one of several dry de-cladding methods. We have benchmarked dry de-cladding methods, analyzed applicability to the advanced spent fuel management process, integrated and compared several configuration, and finally derived detailed specifications proper to requirements for the device. Also, thermal characteristics of the device such as thermal stress and strain have been analyzed by the commercial software, 1-DEAS, and the reliability of the results have been verified by the KOLAS(Korea Laboratory Accreditation Scheme). The UO$_2$ solid pellets are put in the device which has a capacity of 20 kgHM per a batch, heated up about 600$^{\circ}C$ in the air environment. Then, the UO$_2$ solid pellets are oxidized into the U$_3$O$\_$8/ powder, and the powder is collected in a special vessel. The device has been designed and developed as fellows: the multi-staged fine hole meshes are used to reduce the size of the powder gradually, heat and air(oxygen) are supplied continuously to reduce the reaction time, and slight vibration effect are applied to collect powder cling to the device.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.2
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• pp.161-167
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• 2017

This paper presents an effective PPG measurement device in a wrist watch for smart healthcare. PPG can be acquired by measuring absorption of light and PPG measurement device is classified as transmission and reflection type. Reflection type is easy to implement but vulnerable to motion artifact. Moreover, reflection type must use 2 hands at once if the device is implemeted in a wrist watch. This paper describes the implementation of robust transmission type PPG measurement device by using previous developed reflection type device. PPG sensor is clip type and can be separated from the device so that the influence of motion artifact can be reduced. The proposed device can transmit the measured signal in real-time and is useful for smart healthcare. For evaluation of the proposed device, PPG signals are compared with reflection type in the same condition. The results show that the proposed device has 20% improvement in performance.