• Journal of Advanced Marine Engineering and Technology
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• v.22 no.5
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• pp.712-720
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• 1998

The effect of H2:N2 gas ratio on the case thickness hardness and nitrides formation in the sur-face of SCM440 machine structural steel have been studied by micro-pulse plasma process. The thickness of compound layer increased with the increase of nitrogen content in the gas com-position. The maximum thickness of compound layer the maximum case depth and the maximum surface hardness were about 15.8${\mu}m$, 400${\mu}m$ and Hv765 respectively in the nitriding condition of 250Pa and 70% nitrogen content at $520^{\circ}C$ for 7hrs. Generally only nitride phases such as ${\'{\gamma}}$($Fe_4N$)$\varepsilon(Fe_2}{_3N}$ phases were detected in compound and diffusion layer by XRD analysis. The amount of $\varepsilon(Fe_2}{_3N}$ phase increased with the increase of nitrogen content. The relative amounts and kind of phases formed in the nitrided case changed with the change of nitrogen content in the gas composition.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.65-69
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• 1989

Mather type dense plasma focus device was develooped for the feasibili쇼 study in its application to the x-ray lithography. To etermine the electrical characteristics,the temporal begavior of the discharge current and the voltage was measured by using the Rogowski coil and the high voltage probe respectively. The results are 9 $\mu\textrm{s}$ of the period, 18m$\Omega$ of resistance and 0.16$\mu$Η of inductance. The average current sheath velocity was measured by the light signal emitted at the moving plasma sheath. The light signal was detected through two fiber bundles. When the applied voltage was 13 kV and the initial jpressure of argon was 21.8 Pa, the best plasma focus was occurred. The x-ray emission characteristics from the plasma focus was determined by the x-ray pictures taken by pinhole camera. It is focus that the plasma was focused at 1.4 cm distant position above the center electrode and its diameter was about 1.0 m.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.172-174
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• 2020

기존의 절대위치 감지 방식은 초기위치를 알기 위하여 이동자의 위치를 초기화해야 하고 생산 단가가 높다는 단점을 보완하기 위해 MR 센서를 이용하여 비접촉 방식으로 선형모터 이동자 절대위치를 판별하는 시스템을 제안하였다. 센서값을 이용하여 절대위치를 판별해야 하기 때문에 ADC 기능과 실시간 연산 기능이 필요하다. 때문에 8bit MCU(Atmega324PA)를 이용했다. 본 논문에서 이용한 MR 센서의 출력 변동폭이 작기 때문에 Instrumentation Amplifier를 이용하여 증폭된 출력을 MCU로 읽어 사용했다. 제안 시스템의 회로 및 알고리즘을 구현하였고 이를 이론적, 실험적 분석을 통해 동작 및 타당성을 검증하였다.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.21-30
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• 2010

This study was performed to develop an active tire pressure control system that can adjust tire pressure to the optimum level according to traveling and working condition of agricultural tractor. For the development of active tire pressure control system, pneumatic supplier, solenoid valve block including pneumatic supply line, infinite rotation type pneumatic supplier with rotary joint unit, tire pressure transceiver module and control algorithm were developed. Also, tire simulator was developed. Using this tire simulator, the feasibility of each part constructing actual system was tested by checking the performance. The average communication success ratio was 98.3% between tire pressure transmitter and receiver module according to the various tire rotational speed and data receipt position of receiver module. The communication performance of the developed transmitter and receiver module was very stable in any condition. The tire pressure control system was accomplished by using the proportional control algorithm in this study. Also tire pressure control performance of developed control system was analyzed by using the tire simulator. As a result of control performance analysis to the developed system, the developed control system took 307 seconds to inflate agricultural tractor's tire from 50 kPa to 180 kPa. In opposite case, it took 210 seconds. Also it was able to control the tire pressure accurately under ${\pm}0.9%$ (FS) in any condition.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.1-16
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• 1999

Differential equations and its numerical solution program using Turbo-C were formulated to describe the radical distribution and average displacement amplitude of vibrating dehydrated contact lens(HEMA) driven by sinusoidal or rectangular pressure. The natural resonant frequency of the lens diaphram(thickness 0.08mm, diameter 14mm, curvature radius 8mm) was measured to be 5730 Hz from the extrapolation of frequency vs addedmass to the diaphram curve. The Young's modulus of the lens was measured to be $4{\times}10^9$ Pa with altering the original shape. The effect of parameters such as thickness, effective radius, damping coeff., amplitude of driving pressure on the vibration characteristics was illustrated by the computer simulation of the derived program. When the frequency of driving pressure coincides with the integral multiple of fundamental resonance frequency of the lens the wave pattern changes from arc to bell-shape along the radial position of the diaphram. If this happens to the contact lens on the cornea in vivo, it might create the feel of pull of the lens due to the increased rise of central part of the lens.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.119-127
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• 2017

This paper presents a study of reinforced earth model wall reinforced by geosynthetics subjected to vertical surcharge. 7 types of reinforced earth model wall were constructed in the model box($100cm{\times}140cm{\times}100cm$) to assess the deformation and stress behavior of model walls according to different tensile strength and laying number of reinforcement and surcharge pressures. 3 types of geosynthetics that have different tensile strength were used as reinforcement. The test was carried out by changing the number of reinforcement to 5, 7, 9, and surcharge pressure to 50, 100, 150, 200, 250 kPa. The model test found that the maximum lateral displacements occurred at the 0.7 H (H : Wall height) position from the bottom of the model wall and vertical stress was low in the smaller surcharge pressure and the larger tensile strength of reinforcement.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.271-275
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• 2013

Shoulder bone scan everyday life, sports activities at the side of the shoulder joint, or applying strong force in the lateral occurs. Mainly on upper arm abduction, temple, other rotational dislocation of the shoulder joint gahaejyeo as useful for observing the presence or absence of lesions is used. Shoulder PA oblique projection prevent distortion of the image due to the angle and the most useful diagnostic radiological investigate shooting angle. Shoulder blade body and the acromion and coracoid process Y-view is formed characters. $10^{\circ}$ angle between the shoulder blades and the acromion is the obstruction. $20^{\circ}{\sim}25^{\circ}$ to the Y-view of the humerus head looks superimposed, the position of the shoulder joint and seemed appropriate. $35^{\circ}$ of the humerus head superimposed on the Y-view, but above the humerus head and shoulder joints were distorted. When $45^{\circ}$ elevation observed on the side of the best has come Y-view also acromion and coracoid process is finished.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.2
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.319-325
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• 2022

The Study In order to obtain a sharpness Image from Skull PA axial projection (Haas) in a head axial X-ray Examination, this study changed the posture angle using Skull Phantom and evaluated the image subjectively to 5 radiologists who worked in the Department of Imaging at University Hospital. In the prone position, the head was lowered 4 cm from the back of the head, entered 25° toward the head, and the image evaluation score was high with 20 points, such as the back bone, dorsum sellae projected in the large hole, and posterior clinoid process. In addition, the score significance was verified, and the Cronbach Alpha value was evaluated to have good reliability of 0.789. As a result of calculating the signal-to-noise ratio (SNR) by setting the region of interest (ROI) of the image, it was the highest at 5.957 for 25° incident at the back of the head and 6.430 for 30° incident at the back of the head. As a result of the study, in order to obtain a sharp image of the back of the head bone, dorsum sellae, and posterior clinoid process when shooting in the axial direction after the head, it is filmed by tilting 25° toward the head from 4 cm below the back of the head. In order to obtain a sharp image of rock pyramid symmetry, petrous ridge, sagittal suture, and lambdoid suture, it is thought that it will be helpful for clinical use if you shoot it 8cm down from the back of the head and tilt it 30° toward the head.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.445-453
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• 2001

The multiple targets tracking problem has been one of the main issues in the radar applications area in the last decade. Besides the standard Kalman filtering, various methods including the variable dimen-sion filter, input estimation filter, interacting multiple model(IMM) filter, dederated variable dimension filter with input estimation, etc., have proposed to address the tracking and sensor fusion issues. In this pa- per, two existing tracking algorithm, i.e, the IMM filter and the variable dimension filter with input estima-tion(VDIE), are combined for the purpose of improving the tracking performance for maneuvering targets. To evaluate the tracking performance of the proposed algorithm, three typical maneuvering patterns, i.e., waver, pop-up, and high-diver motions, are defined and are applied to the modified IMM filter as well as the standard IMM filter. The smaller RMS tracking errors, in position and velocity, of the modified IMM filter than the standard IMM filter are demonstrated though computer simulations.