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A Simple Security Architecture for Mobile Office
Seungcheon Kim,Hoon Jin 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.1
The Mobile Offices services based on Bring Your Own Device (BYOD) are getting more popular as the use of smart phone grows rapidly. As the free wireless services are being spread, malicious codes can be spread easily. Therefore, how we will provide security in an environment of free wireless has become an issue. This paper suggests security architecture for the better mobile office security and presents required procedures and the analysis of the expected security enhancement.
Spray Characteristics of GDI Injectors with Different Hole Diameter
( Seungcheon Ro ),( Jeonghyun Park ),( Hanbin Jo ),( Suhan Park ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
The purpose of this paper is to investigate the effect of the different hole diameter on the spray and droplet atomization characteristics in a gasoline direct injection (GDI) injector. In order to understand the spray characteristics, the frozen spray images were captured by high speed camera with light-source in the constant-volume chamber. The spray characteristics, such as the spray tip penetration, spray area, and spray width, were calculated and analyzed from the captured spray images using MATLAB code. The atomization characteristics were analyzed through the droplet size, distribution, and velocity. The droplet size and velocity were measured by the phase Doppler anemometry (PDA). The test injectors have a single-hole, and the difference of hole diameter among test injectors was set to 30 ㎛. The test was conducted under the following experimental conditions: injection pressure of 50 bar to 200 bar with 50 bar step, ambient pressure of 5 bar and 15 bar, energizing duration of 1.5ms. The experimental results showed that the larger the injector hole diameter, the longer spray tip penetration and the larger the spray area for the same time. As the diameter increases, the injection quantities increase and the spray momentum increases accordingly. Because of the large amount of spray momentum, injectors with large hole diameter have long spray tip penetration and wider spray areas. In the vicinity of the nozzle tip, the spray width over time tends to be similar to the injection rate result. It can be seen that the spray width has a close relationship with the injection rate. The larger the hole diameter, the larger the Sauter mean diameter (SMD) and the smaller the droplet velocity. As the injection pressure increased, the SMD decreases and droplet velocity increases.
Seungcheon Ro,Byunggyun Kim,Su Han Park,Young-Bae Kim,Byungchul Choi,Seunghun Jung,Dong-Weon Lee 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.1
The purpose of this study is to investigate effects of length-to-width (L/W) ratio on cavitation flow inside a transparent acrylic nozzle orifice, and its effects on spray angle. Three visualization nozzles with different geometries (L/W = 2.0, 2.67, and 4.0) are used, and the working fluid is water. In order to visualize the development process of cavitation, the injection pressure of the working fluid is changed, and a high-speed camera is used with a metal-halide lamp. From experiments and analysis, some important facts are determined. As the injection pressure increases, the cavitation length and thickness increase linearly until the hydraulic flip occurs. Although the cavitation width varies according to the orifice width, the maximum cavitation thickness relative to the orifice width is almost constant at approximately 25 % ~ 30 %. When the nozzle shape ratio increases, the discharge coefficient tends to increase because of the decrease in friction area. When entering the hydraulic flip region, the discharge coefficient decreases due to the reduction of the exit section area. The spray angle is affected by the cavitation number, cavitation length, cavitation thickness, and Reynolds number. The higher the injection pressure, the higher the turbulence intensity, and the greater the instability of the fluid flow.
Smart Pet Care System using Internet of Things
Seungcheon Kim 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.3
Since Internet of Things(IoT) have come to our lives, we have developed various smart services using IoT. This paper introduces a smart pet care system that is working in an environment of Internet of Things (IoT). Basic services of the proposed smart pet care system are: Remote feeding, remote controlled automatic defecation, CCTV service and Smart phone APP that can provide the control information of the above services. Basic architecture and system implementations are introduced with the details of services.
Analysis of Trace Aluminium Oxide in UO2 Using ICP-AES
Seungcheon Lee,Jaeseok Lee,Tae-Hong Park,Hye-Ryun Cho,Jai Il Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
To improve the safety of nuclear fuel, research on the advanced nuclear fuel (UO2) by adding various trace elements is being conducted. For example, the addition of metals such as Mo, Cr can improve the thermal conductivity of nuclear fuel, minimizing the diffusion of fission products. Trace metal oxide additives (SiO2, Cr2O3, Al2O3, etc.) can suppress the release of fission gases. In general, complete dissolution of the fuel sample is required for chemical analysis to determine its elemental compositions. Among widely used metal oxide additives, aluminum oxide is difficult to dissolve in nitric acid due to its excellent thermal and chemical stability. In this study, we investigated on different chemical dissolution methods by applying a microwave digestion system under various acid solutions. We confirmed the validity of the digestion method by carrying out trace element analysis using an Inductively-Coupled Plasma Atomic Emission Spectrometer (ICP-AES).