• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.423-424
• /
• 2011

This paper has proposed a 920 MHz RF front-end for IEEE 802.15.4g SUN (Smart Utility Network) systems. The proposed 920 MHz RF front-end consists of a driver amplifier, a low noise amplifier, and a RF switch. In the TX mode, the driver amplifier has been designed as a single-ended topology to remove a transformer which causes a loss of the output power from the driver amplifier. In addition, a RF switch is located in the RX path not the TX path. In the RX mode, the proposed low noise amplifier can provide a differential output signal when a single-ended input signal has been applied to. A LC resonant circuit is used as both a load of the drive amplifier and a input matching circuit of the low noise amplifier, reducing the chip area. The proposed 920 MHz RF Front-end has been implemented in a 0.18-um CMOS technology. It consumes 3.6 mA in driver amplifier and 3.1 mA in low noise amplifier from a 1.8 V supply voltage.

• Journal of the Society of Disaster Information
• /
• v.13 no.3
• /
• pp.305-312
• /
• 2017

In our society, the advanced, advanced, and information industries have continued to grow and now live in the era of the fourth industrial revolution. As the industry develops, the load of the users has also increased so much that it is deepened by the energy shortage phenomenon and the construction of additional energy facilities is required. Therefore, energy plant construction work is being actively carried out in the coastal area. In particular, it is common to build a plant in the ground by filling the coast with soil in other regions, reflecting the fact that Korea is lacking in the country when constructing power plants, gas and petrochemical plants. Current domestic grounding designs are designed or constructed to suit only the use of grounding resistors based on the electrical equipment design technical standards. However, in the case of a plant facility constructed in the untested buried soil, when the lightning current and the abnormal current are inputted, the facility operator or the user due to the elevation of the ground potential is seriously exposed to the risk of electric shock disaster. In this paper, we analyze the ground resistivity of the landfilled soil and use a computer program (CDEGS) based on KS C IEC 61936-1, We analyze the contact voltage and stratification voltage and propose a grounding design optimized for plant installation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.9 no.2
• /
• pp.113-119
• /
• 2011

Safe operation and maintenance of engineered dry storage systems for spent fuel from nuclear power plants basically depends on adequately adopted design requirements. The most important design target of the system are those which provide the necessary assurances that spent fuel can be received, handled, stored and retrieved without undue risk to health and safety of workers and the public. To achieve these objectives, the design of the system incorporates features to remove spent fuel residual heat, to provide for radiation protection, and to maintain containment over the lifespan of the system as specified in the design specifications. The features also provide for all possible anticipated operational occurrences and design basis events in accordance with the design basis as guided by the designated regulations. The general performance requirements of a projected storage system are introduced in this paper. The storage system is designed to store fuel assemblies in associated with designated regulatory requirements. Small increases/decreases in maximum burnup can be adjusted with cooling time. These variations are compensated for by a corresponding small site-specific increase/decrease in the design basis-cooling period, as long as the maximum heat load and radioactivity of loaded fuel assemblies are met. Generic design basis events considered for the storage system are summarized. Shielding and radiological requirements along with mechanical and structural are derived in this study.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.11
• /
• pp.626-634
• /
• 2004

In a client-server model, network server systems suffer from both heavy communication and computational loads. While communication channels become increasingly speedy, the existing protocol stack architectures still include mainly three performance bottlenecks of protocol stack processing, system call, and network interrupt overheads. To address these obstacles, in this paper we present a host-independent network system where a network interface card (NIC) is utilized in an efficient manner. First, by offloading network-related portion to the NIC, the host can fully utilize its processing power for other useful purposes. Second, it eliminates the system call overhead, such as context-switching and memory copy operations, since the host communicates with the NIC through its user-level libraries. Third, it a] so reduces the network interrupt operation count as the host handles the interrupt in a segment instead of a packet. The experimental results show that the proposed network system reduces the host CPU overhead for communication system by 68-71%. It also shows that the proposed system improves the communication speed by 11-83% under heavy computational and communication load conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.9
• /
• pp.581-588
• /
• 2016

Piezoelectric thick films of a soft $Pb(Zr,Ti)O_3$ (PZT) based commercial material were produced by a conventional tape casting method. Thereafter, the interdigitated (IDT) Ag-Pd electrode pattern was printed on the $25{\mu}m$ thick piezoelectric film at room temperature. Co-firing of the 10-layer laminated piezoelectric thick films was conducted at $1,100^{\circ}C$ and $1,150^{\circ}C$ for 1 h, respectively. Piezoelectric cantilever energy harvesters were successfully fabricated using the IDT electrode pattern embedded piezoelectric laminates for 3-3 operation mode. Their energy harvesting characteristics were investigated with an excitation of 120 Hz and 1 g under various resistive loads (ranging from $10k{\Omega}$ to $200k{\Omega}$). A parabolic increase of voltage and a linear decrease of current were shown with an increase of resistive load for all the energy harvesters. In particular, a high output power of 3.64 mW at $100k{\Omega}$ was obtained from the energy harvester (sintered at $1,150^{\circ}C$).

• Korean Journal of Community Nutrition
• /
• v.4 no.1
• /
• pp.83-94
• /
• 1999

This study was carried out to investigate the general characteristics of public health nutritionists, the current status of nutrition services operation, the recognition about nutrition services of public health center related man power, the job satisfaction and self-assessment and the need for a retraining course of public health nutritionists. The subjects were 58 public health nutritionists who responded to the questionnaire distributed at the annual retraining program in 1998. The results of this study are summarized as follows. 1) 46.5% of the nutritionists were 26-30 years old, 62.1% were 4 year university graduates 74.1% were food and nutrition majors and 51.7% were daily workers. 2) Among the public health center-related manpower, the recognition about nutrition services was the highest for the manager of family health section, followed by the head of public health centers, and then the general nurse in public health centers. 3) The ranking of the reasons for job satisfaction of the public health nutritionists was, relationship with colleagues(3.84), inhabitants response after nutrition counselling(3.53), specialized value realization/conviction about duty(3.35), contents of the work(3.10), value achievement(3.08), self achievement/development(3.00), self discretion(2.92), participation in policy decisions(2.90), work load(2.75), chance of retraining and acquisition of new information(2.73), working environment(2.69), supervisio $n^port by superiors(2.67), salary(2.38), supply of necessary education material, technique(2.37), and budget security(2.22). 4) The satisfaction of the inhabitant's responses after nutrition counseling was the highest among the 4 year university graduates(p<0.05), the satisfaction of the specialized value realization/conviction about duty was the highest among the nutritionists 26-30 years old(p<0.05). Food and nutrition majors(p<0.05) and those having worked less than 3-5years at public health centers also showed much satisfaction(p<0.05). Satisfaction with the salary was the lowest among the food and nutrition majors(p<0.01) and daily workers(p<0.001). The satisfaction with the participation in policy decisions was the lowest among the daily workers(p<0.01). 5) The ranking for the level of self-assessment were, nutrition and dietetic practice(2.92), communication(2.80), management(2.77), public health science and practice(2.66)(p<0.01). The general characteristics such as the level of education, major, employment condition, current public health center's tenure, and charge experience of the nutrition guidance work were not significantly related to self-assessment except the management part(p<0.05). The higher the satisfaction of specialized value realization/conviction about the duty, the better the total score on the self-assessment(p<0.05)..

• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.05b
• /
• pp.455-459
• /
• 2003

In the great motive power which promotes the Game of future to develop. three main factors focus on 3D Graphics, Network and Virtual Reality. the Network technique as necessary elemental technique in Next-generation on-line game is being researched largely. However, from viewing the features of on-line game, if many users meet in same server, it not only causes heavy load to the server and brings inconvenience to the users, but also increases expense to the service provider and creates a problem which is to put up server or not. A proposal is going to do hybrid distributed system a client hardly depends on server for this paper, and to be able to enjoy a network game through information alternating current between clients. depended on the existing server, and the most message processing did a design in order to achieve between clients. A design way to propose is as follows. Primarily it was done in order proposed a message grade anger process way, and to be able to manage server or a client according to importance of message, and, with the second, did a Client-Server method and a Pear-to-Pear method at the same time, and a chase did efficiency. Third is going to propose other problem solving way by message grade anger in multi-anger and a security section of a message cue.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.6
• /
• pp.846-855
• /
• 2021

Eco-friendly and renewable energy sources are actively being researched in recent times, and of shore wind power generation requires advanced design technologies in terms of increasing the capacities of wind turbines and enlarging wind turbine installation vessels (WTIVs). The WTIV ensures that the hull is situated at a height that is not affected by waves. The most important part of the WTIV is the leg structure, which must respond dynamically according to the wave, current, and wind loads. In particular, the wave load is composed of irregular waves, and it is important to know the exact dynamic response. The dynamic response analysis uses a single degree of freedom (SDOF) method, which is a simplified approach, but it is limited owing to the consideration of random waves. Therefore, in industrial practice, the time-domain analysis of random waves is based on the multi degree of freedom (MDOF) method. Although the MDOF method provides high-precision results, its data convergence is sensitive and difficult to apply owing to design complexity. Therefore, a dynamic amplification factor (DAF) estimation formula is developed in this study to express the dynamic response characteristics of random waves through time-domain analysis based on different variables. It is confirmed that the calculation time can be shortened and accuracy enhanced compared to existing MDOF methods. The developed formula will be used in the initial design of WTIVs and similar structures.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.529-535
• /
• 2018

The range extender vehicle runs on a mechanism that allows the small power generation engine to start in the most efficient specific operating range to charge the battery and extend the mileage. In this study, we developed a step motor type intake air supply system that replaces existing throttle body system to develop a simple low cost control logic system. The system was applied to the existing base engine, and in order to improve the performance by increasing the amount of intake air, the effect of changing the length of the intake and exhaust manifold was experimentally examined. As a result, the Type B intake air control actuator operated by one step motor showed higher performance than the Type A in all the operation region, but the performance was lower than that of the base engine due to the increase of flow resistance. To improve this, it was confirmed that the engine performance was improved at both speeds of 2200rpm and 4300rpm when the 140mm adapter was installed in the intake manifold and when the newly designed 70mm exhaust manifold was applied. Through this process, high - precision operation control was realized by connecting the generator load to the optimized engine for the range extender electric vehicle. Experimental results showed that the speed change rate was within ${\pm}2.5%$ at 2200rpm in 1st stage and 4300rpm in 2nd stage and the speed follow-up result of 610 rpm/s was obtained when the speed was increased from 2200rpm to 4300rpm.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.6
• /
• pp.74-79
• /
• 2019

The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.