• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.207-210
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• 2005

The results of combustion performance test of fuel-rich gas generator with dual swirl injectors are described. By changing simulating duct and recess number(RN) of the injectors, we inspected whether the combustion instability took place. When the injectors of RN = 0.5 were used, combustion instabilities could be reduced using the simulating duct. However, the effect of the simulating duct on the gas generator with the injectors of RN = 1.5 was not significant.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.97-101
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• 2001

Recently, an excavated soil-recycling machine has been receiving considerable attentions. The mobile type excavated soil-recycling machine is able to improve the soils by adding the additives such as slaked lime and cement at the construction site. However, not only the mechanical factors such as paddle inclination angle and pitch of the paddle but also the physical properties of the excavated soils affect the mixing performance of the excavated soils and additives. In this sense, experimental investigations are uneconomical and ineffective. This paper concerns with the numerical simulator to analyze the mixing behavior of excavated soils and additives in the soil-recycling machine with dual shafts in order to assist the economical and effective design of the optimum soil-recycling machine. By using the simulator, several simulations were carried out, and the effects of some mechanical parameters such as the paddle inclination angle and pitch of the paddle on the mixing performance were made clear.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.175-180
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• 2008

This paper is dedicated to the development of cooling devices such as mLHP with Fan-Fin system limited by noise and vibration. As we know, Heat pipe has the limitation of cooling capability to cool down the electronics. It is bounded by capillary and thermal limitation but heat load that it has to deal with is increasing. Especially Today's electronic technology has a tendency to integrate lots of function into the small piece of a processor like Dual core having 35W heat load for mobile and desktop computer respectively. There is an optimum operating condition of temperature, below $70^{\circ}C$, during the maximum heat load, 35W. There is the motivation needed to develop the new type of cooling devices and we can discuss about the new challenge beyond heat pipe.

• Transactions on Electrical and Electronic Materials
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• v.1 no.3
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• pp.18-22
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• 2000

In this work, we reported the sulfur compositional variation of ZnS$\_$x/Se$\_$1-x/ epitaxial layers with growth temperature and BEP ration of ZnX/Se/)P$\_$ZnS//P$\_$Se/) grown on GaAs substrates by molecular beam epitaxy. The sulfur composition of ZnSSe epitaxial layers was varied sensitively on the growth temperature and show different linear relationship with growth temperature and BEP ration of ZnS/Se(P$\_$ZnS//P$\_$Se/), which revealed -0.107 %$\^{C}$ at (P$\_$ZnS//P$\_$Se/)=0.30 and -0.052 %$\^{C}$ at (P$\_$ZnS//P$\_$Se/)=0.158 rspectively. A reference data for the accurate control of the sulfur composition and the growth of high quality ZnSSe/GaAs epitaxial layers was provided.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.57-66
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• 2021

The reactivity controlled compression ignition (RCCI) is the technology that provides two different types of fuel to the combustion chamber with the advantage of significantly reducing particulate matter and nitrogen oxides emissions. However, due to the characteristics of lean combustion, combustion efficiency is worsened. The conventional type of pistons for conventional diesel combustion (CDC) has mostly been used in the researches on RCCI. Because the pistons for CDC are optimized to enhance flow and target spray, the pistons are unsuitable for RCCI. In this study, a piston that is suitable for RCCI is designed to improve combustion efficiency. The new piston was designed by considering the factors such as squish geometry, bowl depth, and surface area. The experiment was carried out by fixing the energy supply to 0.9kJ/cycle and 1.5kJ/cycle respectively. The two pistons were quantitatively compared in terms of thermal efficiency and combustion efficiency.

• Radiation Oncology Journal
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• v.14 no.3
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• pp.237-244
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• 1996

Purpose : The accurate dosimetry of independent collimator equipped for 6MV and 15MV X-ray beam was investigated to search for the optimal correction factor. Materials and Methods : The field size factors, beam quality and dose distribution were measured by using 6MV, 15MV X-ray Field size factors were measured from $3{\times}3cm^2$ to $35{\times}35cm^2$ by using 0.6cc ion chamber (NE 2571) at Dmax. Beam qualities were measured at different field sizes, off-axis distances and depths. Isodose distributions at different off-axis distance using $10\times10cm^2$ field were also investigated and compared with symmetric field. Result: 1) Relative field size factors was different along lateral distance with maximum changes in $3.1\%$ for 6MV and $5\%$ for 15MV. But the field size factors of asymmetric fields were identical to the modified central-axis values in symmetric field, which corrected by off-axis ratio at Dmax. 2) The HVL and PDD was decreased by increasing off-axis distance. PDD was also decreased by increasing depth For field size more than $5{\times}cm^2$ and depth less than 15cm, PDD of asymmetric field differs from that of symmetric one ($0.5\~2\%$ for 6MV and $0.4\~1.4\%$ for 15MV). 3) The measured isodose curves demonstrate divergence effects and reduced doses adjacent to the edge close to the flattening filter center was also observed. Conclusion . When asymmetric collimator is used, calculation of MU must be corrected with off-axis and PDD with a caution of underdose in central axis.

• Progress in Medical Physics
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• v.20 no.1
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• pp.43-50
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• 2009

The 4 bank mico-MLC (mMLC; Acculeaf, Direx, Isral) has been commissioned for clinical use of linac based stereotactic radiosurgery. The geometrical parameters to control the leaves were determined and comparisons between measured and calculated by the calculation model were performed in terms of absolute dose (cGy/100 MU). As a result of evaluating calculated dose for various field sizes and depths of 5 and 10 cm in water in the geometric condition of fixed SSD (source to surface distance) and fixed SCD (source to chamber distance), most of differences were within 1% for 6 MV and 15 MV x-rays. The penumbral widths at the isocenter were approximately evaluated to 0.29~0.43 cm depending on the field size for 6 MV and 0.36~0.51 cm for 15 MV x-rays. The average transmission and leakage for 6 MV and 15 MV x-rays were 6.6% and 7.4% respectively in single level of leaves fully closed. In case of dual level of leaves fully closed the measured transmission is approximately 0.5% for both 6 MV and 15 MV x-rays. Through the commissiong procedure we could verify the dose characteristics of mMLC and approximately evaluate the error ranges for treatment planning system.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.1
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• pp.60-81
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• 2008

This thesis is written about the causes, the processes and the treatments of edema. It consists of 31 chapters. Covering 11 chapters, there are prescriptions and constructions. When one of the organs fails to work metabolizing water, you can have edema. It is the result of the accumulation of excess fluid under the skin. Edema most commonly occurs in the head facial, the palpebral portion, the feet and legs or all the body. Sometimes it is accompanied with ascites. There are three classifications in the thesis. First, according to the cause and the symptom of disease, it is divided into 5 types. Type 1. The swelling caused by the disorder of the lungs from the troubling wind. Type 2. The swelling caused by the weak spleen. Type 3. The swelling caused by abnormal condition between the kidneys and the lungs. Type 4. The swelling in abdomen caused by the weak kidneys. Type 5. The swelling (Yellow sweat) caused by the heat inside body as water outside. Second, the swelling and the abnormal symptom of five viscera. Third, the swelling accompanied with menstruation in female and with chilliness. In short, the original textbook is showed that the treatment of edema focuses on the cause and the region of fluid accumulation. When the swelling is in the upper body or the cause of diseaseis outside, the useless humidity can be expelled through sweating. On the other hand, when the swelling is in the lower body or the cause of disease is inside, it is pushed out by urination. In this book, the author presents further treatments. And these treatments are often cited by doctors after ages. Even one of them suggested that the swelling be divided by cosmic dual forces. In spite of many researches, it is too complicate for us to understand the writer’s intend. For that reason, comparing with other medical books and referring to guides explained by doctors, I have studied the textbook to help understand.

• Radiation Oncology Journal
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• v.10 no.1
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• pp.107-113
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• 1992

Increasing frequency of skin cancer, mycosis fungoides, Kaposi's sarcoma etc, it need to treatment dose planning for total skin electron beam (TSEB) therapy. Appropriate treatment planning for TSEB therapy is needed to give homogeneous dose distribution throughout the entire skin surface. The energy of 6 MeV electron from the 18 MeV medical linear accelerator was adapted for superficial total skin electron beam therapy. The energy of the electron beam was reduced to 4.2 MeV by a $0.5\;cm\times90\;cm{\times}180\;cm$ acryl screen placed in a feet front of the patient. Six dual field beam was adapted for total skin irradiation to encompass the entire body surface from head to toe simultaneously. The patients were treated behind the acryl screen plate acted as a beam scatterer and contained a parallel-plate shallow ion chamber for dosimetry and beam monitoring. During treatment, the patient was placed in six different positions due to be homogeneous dose distribution for whole skin around the body. One treatment session delivered 400 cGy to the entire skin surface and patients were treated twice a week for eight consecutive weeks, which is equivalent to TDF value 57. instrumentation and techniques developed in determining the depth dose, dose distribution and bremsstrahlung dose are discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1340-1350
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• 2009

The design and implementation of planar Active Phased Array Antenna System are described in this paper. This Antenna system operates at X-band with its bandwidth 10 % and dual polarization is realized using dual slot feeding microstrip patch antenna and SPDT(Single Pole Double Through) switch. Array Structure is $16\times16$ triangular lattice structure and each array is composed of TR(Transmit & Receive) module with more than 40 dBm power. Each TR module includes digital attenuator and phase shifter so that antenna beam can be electronically steered over a scan angle$({\pm}60^{\circ})$. Measurement of antenna pattern is conducted using a near field chamber and the results coincide with the expected beam pattern. From these results, it can be convinced that this antenna can be used with control of beam steering and beam shaping.