• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.4
• /
• pp.398-405
• /
• 2016

A shape of loop-pipe in a compressor affects the vibration of compressor. In this paper, optimal design of shape of loop-pipe to decrease the stress was carried out. Body and shell were assumed to be rigid, while loop-pipe is considered to be flexible. The finite element model was derived and programmed. Genetic algorithm was used for optimization. Locations of 18 point in loop-pipe were considered as shape variables, while the shapes of loop-pipe were interpolated as polynomials or ellipses. Maximum stress of loop-pipe was used as a fitness function for optimization. The spatial constraints and acceleration response of shell were also considered in optimization. The maximum stress and acceleration could be reduced by 79 % and 49 % respectively.

• 보존과학연구
• /
• s.27
• /
• pp.83-102
• /
• 2006

The Suchon-ri tomb No. 1 is the earliest one among the Suchon-ri tombs excavated in 2003. The Suchon-ri tomb No. 1 yielded a number of valuable artifacts furnished with burial goods such as gilt bronze items of a crown, a pair of earrings and shoes and a loop-handled sword with inlaid silver decoration. In particular, a loop-handled sword drew scholarly attention in that it showed characteristics of Baekje such as wave patterns on a silver plate decorated in the handle and sheath and inlaid dragon design on the loop-handle. In the process of the reproducing the loop-handled sword, classification methods of the loop-handled swords, iconography decorated on the swords, unearthed loop-handled swords of the Three Kingdoms Period have been investigated along with studying the reproduction cases in Japan. In addition to the study focused on the shape of the swords, manufacturing techniques have been thoroughly analyzed through scientific methods. Finally, based on the synthesis of a series of studies and analyses, traditional manufacturing techniques employed by Baekje artisans had been inferred and a replica of the loop-handled sword was manufactured with the traditional methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.2A
• /
• pp.96-101
• /
• 2003

This paper is on the user equipment (UE) side time tracker design and implementation of the wideband code division multiple access (WCDMA) system. The time tracker is constructed as a second order closed loop including time error detector (TED), loop filter (LP), numerically controlled oscillator (NCO), and sample selector (SS). Through the simulation, we found the gain of the TED as a function of the CPICH power contribution to the total transmission power of the base station. Also we derived the transfer function of the loop and the BER versus DPCH power relationships where timing offsets and loop noise bandwidths are used as parameters. In the curve, we can conclude that there are appropriate loop noise bandwidths according to the given environments for the better performance.

• ETRI Journal
• /
• v.36 no.6
• /
• pp.881-888
• /
• 2014

This paper studies the magnetic coupling between two adjacent loop antennas that are parallel to each other in a plane and presents a new practical method to avoid the resulting magnetic coupling interference. The study focuses on the high frequency radio-frequency identification (RFID) system for casino applications, where several loop antennas are closely built into a game table to monitor gaming chips. In this case, neighboring loop antennas may severely interfere with each other by magnetic coupling, which leads to the malfunction of the RFID system. In this paper, we present a practical loop antenna with a new loop switch circuit for avoiding magnetic coupling. The loop switch circuit is integrated with a matching circuit and automatically operated by using an interrogating signal from a reader. We verified the validity of the proposed design by showing that an RFID reader with the proposed antenna can exactly and separately read the gaming chips placed on the different betting zones of a game table.

• Journal of IKEEE
• /
• v.17 no.1
• /
• pp.16-21
• /
• 2013

Recently, frequency synthesizers are being designed in two ways narrow-band loop or dual-loop for wide-band to reduce the phase noise. However, dual-loop has the disadvantage of center frequency mismatch and requiring an extra loop. In this paper, we propose a new structure that supports a range of 800Mhz ~ 3Ghz with multiple control of the single-loop frequency synthesizer without another loop. The control voltage of the VCO(coarse, fine) will be fixed, and finally the VCO will have a low Kvco. The frequency synthesizer is simulated using UMC $0.11{\mu}m$ process, proposed frequency synthesizer can be used in a variety of applications in the future.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.2
• /
• pp.216-223
• /
• 1996

The active power factor control AC/DC converter needs a current loop compensator to obtain better dynamic characteristics and power factor performance, but the optimal design of a current loop compensator is difficult because the AC/DC converter is a nonlinear system having periodically varying poles and zeros. The predictive current control scheme generates a control input using the dynamic equations of the AC/DC converter so that the dynamic of the AC/DC converter is included in the controller and the necessary bandwidth and the gain characteristics of the current control loop are satisfied. And as a result, a compensator becomes unnecessary and the current loop shows the improved current loop characteristics. In this paper, a power factor controller without current loop compensator by adopting a predictive current control scheme is designed and the designed power factor controller is modelled by using a small signal perturbation modelling technique, and simulated to investigate its small signal characteristics. A 200 W power factor control AC/DC converter is built to verify the effectiveness of the proposed power factor controller.

• Nuclear Engineering and Technology
• /
• v.53 no.12
• /
• pp.3918-3929
• /
• 2021

In this study, we experimentally investigate of a two-phase natural circulation loop that functions as a passive containment cooling system (PCCS). The experimental apparatus comprises two loops: a hot loop, for simulating containment under severe accidents, and a natural circulation loop, for simulating the PCCS. The experiment is conducted by controlling the pressure and inlet temperature of the hot loop in the range of 0.59-0.69 MPa (abs) and 119.6-158.8 ℃, respectively. The heat balance of the hot loop is established and compared with a natural circulation loop to assess the thermal reliability of the experimental apparatus, and an additional system is installed to measure the vapor mass flow rate. Furthermore, the thermal-hydraulic characteristics are considered in terms of a temperature, mass flow rate, heat transfer coefficient (HTC), etc. The flow rate of the natural circulation loop is induced primarily by flashing, and a distortion is observed in the local HTC because of the fully develop as well as subcooled boiling. As a result, we present the amount of heat capacity that the PCCS can passively remove according to the experimental conditions and compared the heat transfer performance using Chen's and Dittus-Boelter correlation.

• Journal of Korea Multimedia Society
• /
• v.12 no.9
• /
• pp.1288-1296
• /
• 2009

This paper is for multi-frequency thin film loop antenna used on smart phone, PMP and PDA like as a multi-media devices. We developed a loop pattern folding methods to reduce a thin film antenna dimension using that mutual coupling folding loop occurs the higher frequency resonation. To reduce the thin film size for loop antenna, we fold the loop pattern repeatedly control the coupling coefficient than generate a not only higher mode resonation but also basic resonation from loop pattern. To realization the thin film folded loop antenna, we used a $30mm{\times}9mm$ PI film the thickness is 20um so that we realize the CDMA850, GPS, DCS, PCS, WCDMA antenna simultaneously and it's radiation efficiency is over 50% and gain is 0dBi.

• Composites Research
• /
• v.26 no.5
• /
• pp.279-288
• /
• 2013

In this paper, the delamination and deformed FSS caused by residual stresses in the Loop type FSS embedded composites and the transmission characteristic changes due to deformation of FSS by residual stresses were studied. FSS may have different electromagnetic characteristics depending on the type of element, design variables, and array. Therefore, design variables of square loop FSS embedded composites structures were determined to obtain the transmission characteristic for X-band (8~12 GHz). Then the design variables of other types of loops (triangular loop and circular loop) were determined based on the dimensions of square loop. Thereafter, the residual stresses and transmission characteristics of FSS embedded composite structures with various single and double loop FSS's, and stacking sequence of composite laminates were compared.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.19 no.2
• /
• pp.38-50
• /
• 1982

A new type of digital phase-locked loop (DPLL) called the modified digital Costas loop is proposed and analyzed. The main feature of the proposed loop is that the phase error detector of the loop has linear characteristic. This results from the use of the tan-1 (.) function in the loop. Accordingly, the DPLL can be characterized by a modulo-2$\pi$ linear difference equation. This paper is diveide into two parts. In Part I we describe the proposed system, and analyze the performance of the first-and second-order loops in the absence of noise by the Phase Plane technique. The locking ranges for the DPLL's to achieve exact locking independently of initial conditions have been obtained in closed forms. Also, the false lock and oscillation phenomena occurring under some initial conditions have been considered. These results have been verified by computer simulation. In Part ll we analyze the proposed system in the presence of noise. The steady state probability density function, mean and variance of the phase error have been obtained by solving the Chapman-Kolmogorov equation. These results will be presented in Part ll.