• The KSFM Journal of Fluid Machinery
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• v.4 no.1 s.10
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• pp.7-13
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• 2001

In developing a multistage compressor, the stage matching is one of the critical design issues. The mismatching can be often observed even if each stage has been proven good and then used as part of a compression system. A good matching among the stages can be achieved by changing various design parameters (i.e., passage cross sectional areas, blades angles, stagger angles, curvature, solidity, etc.). Therefore, designers need to find out what parameters must be changed and how much. In this study, a method to search the design parameters for optimum stage matching has been used based on an 1-D mathematical model of a compressor, which uses the data obtained from the preliminary test to identify the design parameters. This methodology is applied with a two-stage axial compressor, which was originally designed for a helicopter gas turbine engine. After identifying design parameters using preliminary test data, an optimization process has been employed to achieve the best matching between the stages (i.e., maximum efficiency of the compressor at its operation modes within a given range of the rotor speed under given restrictions for required stall margins and mass flow). 3-D flow calculations have been performed to confirm the usefulness of the corrections based on the 1-D mathematical model. Calculational results agree well with the experimental data in view of the performance characteristics. Some promising results were produced through the methodology proposed in this paper in conjunction with flow calculations.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.103-110
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• 2007

The High Temperature Gas-cooled Reactor (HTGR) possesses inherent safety features and is recognized as a representative advanced nuclear system for the future. Based on the success of the HTR-10, the long-time operation test and safety demonstration tests were carried out. The long-time operation test verifies that the operation procedure and control method are appropriate for the HTR-10 and the safety demonstration test shows that the HTR-10 possesses inherent safety features with a great margin. Meanwhile, two new projects have been recently launched to further develop HTGR technology. One is a prototype modular plant, denoted as HTR-PM, to demonstrate the commercial capability of the HTGR power plant. The HTR-PM is designed as $2{\times}250$ MWt, pebble bed core with a steam turbine generator that serves as an energy conversion system. The other is a gas turbine generator system coupled with the HTR-10, denoted as HTR-10GT, built to demonstrate the feasibility of the HTGR gas turbine technology. The gas turbine generator system is designed in a single shaft configuration supported by active magnetic bearings (AMB). The HTR-10GT project is now in the stage of engineering design and component fabrication. R&D on the helium turbocompressor, a key component, and the key technology of AMB are in progress.

• The Journal of the Korean dental association
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• v.16 no.1 s.104
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• pp.43-50
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• 1978

The purpose of this study is to determine the effects of Cyclophosphamide on the healing process of fractures of the mice. Tweny-one young adult male mice were used. All of them were experimentally fractured in the left mandibular body areas, and Cyclophosphamide 0.1mg. per 30gr. body wt. was administrated intramuscularly to the experimental group. the mice of both control and experimental groups were sacrificed 1,3,5,7,10,14, and 21st day after operations and microscopic slides were made. The author has observed the histopathological findings. The results were as follows; 1. There were no specific difference between the experimental and control group in the early stage (1~5th day after operation) of the healing process of the mandibular fracture. 2. In the healing process of fractures 7-10th day after operation, the fibrous tissure formation and osteoblastic activity were poor in the experimental groop compared with the control group. 3. In the healing process of fractures 14-21th day after operation, the connective tissue and new bone formation were very poor in the experimental group compared with the control group. 4. On the whole, cyclophosphamide affected the experimentally fractured wound to delay healing in the jaw bone of the mice.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.319-324
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• 2006

Studied was a strategy of technology development for railway system in terms of railway network. First, The successful launch of the Korean HST system has not only decreased logistics burden but also significantly transformed the Korean trunk-line railway network, revolutionizing the logistics and technology sectors and reinvigorating the Korean railway industry in one century. Korean railway industry sector is now investing to develop many different types of railway system(G7, Post G7, tilting train...) so that these kinds of various railway system development should be integrated with the National Inter-modal Transportation Network Plan. To secure sufficient capacity that is required by the National Railroad Plan, the railway industry needs to establish mid- and long-term train purchase and operation strategies in compliance with railway construction and operation policies. During a railway construction planning, train operators, based on their train operation strategies, should come up with measures to closely cooperate with project operators from the planning stage through to the opening of a railway system. To be more precise, train operators should establish long-term train procurement plans reflecting both long-term national railroad network plans and plans for each railway line in order to suggest appropriate roles and schedules for each line. Also, based on the long-term railway plan, directions should be decided concerning the research and development of trains in advance.

• The Journal of the Korean life insurance medical association
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• v.3 no.1
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• pp.149-162
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• 1986

We had experienced very rare a case of renal cell carcinoma through ultrasonic diagnosis, september, 1985 at medical dept. Dae Han Kyoyuk Ins. Company. The conclusions that we gained, making a comparative-analysis of operation's view and ultrasonic view are as follows; 1. Echolucent area which was $0.6cm^2$ size in the center of tumor was shown by ultrasonography, we noticed it occured necrosis or cystic change and the extracts grossly after. operation accorded with ultrasonic view. 2. Tumor was 65mm in diameter on ultrasonography and made clear 55mm in diameter after operation 3. There was not fever, anemia, even typical triad of renal cell carcinoma, blood pressure was within normal limits. 4. The case was stage I by Robson's Modification method. 5. The case was clear cell type by classifying of histology. 6. The affected site was left side and origin was lower pole of the kidney. 7. After radical nephrectomy, until present prognosis was favorable and he exists.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.77-77
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• 1993

Laryngeal web is formed from various causes, and it is a scar tissue covered with epithelium on both sides. The purpose of the laryngeal web surgery is to cover the vocal cords with healthy epithelium and to achieve the normal or near normal function of respiration and phonation. Until now, a lot of surgical procedures were introduced, but have some merits and disadvantages. Recently authors tried this new surgical technique on 6 patients using the suspension laryngomicroscope under the intubation general anesthesia, which was to suture the upper and lower edges of the severed web. This new approach has several advantages; 1) familiar instruments and visual field 2) no unnecessary surgical trauma beyond the operation field 3) one stage operation 4) shorter operation time 5) no serious complications 6) short hospitalization, etc.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.94-103
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• 2019

Self Organizing Map (SOM) is a neural network that is effective in classifying patterns that form the feature map by extracting characteristics of the input data. In this study, we propose an algorithm to determine the cell formation and the machine layout within the cell for the cell formation problem with operation sequence using the SOM. In the proposed algorithm, the output layer of the SOM is a one-dimensional structure, and the SOM is applied to the parts and the machine in two steps. The initial cell is formed when the formed clusters is grouped largely by the utilization of the machine within the cell. At this stage, machine cell are formed. The next step is to create a flow matrix of the all machine that calculates the frequency of consecutive forward movement for the machine. The machine layout order in each machine cell is determined based on this flow matrix so that the machine operation sequence is most reflected. The final step is to optimize the overall machine and parts to increase machine layout efficiency. As a result, the final cell is formed and the machine layout within the cell is determined. The proposed algorithm was tested on well-known cell formation problems with operation sequence shown in previous papers. The proposed algorithm has better performance than the other algorithms.

• Journal of Korean Neurosurgical Society
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• v.29 no.5
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• pp.635-639
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• 2000

Objective : Surgery for the microvascular decompression is mostly concerned with injury to the cranial nerves or brain stem by cerebellar retraction. Intraopeartive brain stem auditory evoked potentials(BAEPs) has been continuously monitored on surgery to evaluate the extent of injury, recovery of the nerves and prognosis. Methods : Of the 161 cases of CP angle surgery from Feb. 1996 to Apr. 1998, 103 cases were monitored during operation. Thirty five patients who had undergone similar surgery were selected and evaluated ; 23 patients were monitored and 12 were not during surgery. If monitor showed more than 0.5 mSec delay of latency, surgeon was given a warning not to retract brain any more. If more than 1mSec delay, surgeon was informed to stop surgery and wait for the returning of evoked potentials. The level of amplitudes and delay of latencies during the initial stage of operation, opening the dura, insertion of teflon patches, and closing the dura and recovery were then compared. Resuls : Twenty patients were male and 15 were female. Their average age was 50.26 years. Mean amplitude during the initial stage of operation was $0.60{\pm}0.25mV$, at opening the dura $0.56{\pm}0.26$, after teflon patches insertion $0.49{\pm}0.20$, and after closure of dura $0.47{\pm}0.28mV$. Mean latency during the early stage of operation was $6.08{\pm}0.67mSec$, at opening of dura $6.38{\pm}0.55$, insertion of teflon $6.97{\pm}0.59$, and closing the dura $6.17{\pm}0.54$. There was statistical significance in the difference of amplitudes between each procedures, and in the difference of latencies. For the complete recovery of amplitude and latency, it usually took average 5.65 minutes(0-20 min). In monitored group, only one patient required more than 20 minutes to recover and suffered from hearing disturbance after surgery. Others were recovered within 10 minutes without complications. However, 4 out of 12 patients who were not monitored showed hearing disturbance, and 1 patient had temporary facial palsy and dizziness(p＝0.000). Conclusion : The results indicate that continuous intraoperative monitoring of BAEPs during CP angle surgery is seen mandatory procedure to prevent operative complications.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.742-750
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• 2007

This paper presents a mathematical model for a double-fleet operation in Korean high speed rail (HSR). KORAIL has a plan to launch new HSR units in 2010, which are composed of 10 railcars. The double-fleet operation assigns a single-unit or two-unit fleet to a segment, accommodating demand fluctuation. The proposed model assumes stochastic demand and uses chance-constrained constraints to assure a preset service level. It can be used in the tactical planning stage of the rail management as it includes several real-world conditions, such as the capacities of the infra-structures and operational procedures. In the solution approach, the expected revenue in the objective function is linearized by using expected marginal revenue, and the chance-constrained constraints are linearized by assuming that demands are normally distributed. Subsequently, the model can be solved by a mixed-integer linear programming solver fur small size problems. The test results of the model applied to Friday morning train schedules for one month sample data from KTX operation in 2004 shows that the proposed model could be utilized to determine the effectiveness of double-fleet operation, which could significantly increase the expected profit and seat utilization rates when properly maneuvered.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.241-250
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• 1996

In this work, an improved architecture of two-dimensional digital filter(2D DF) is suggested, and then the filter is simulated by C, VHDL language and related layouts are designed by Berkeley CAD tools. The 2D DF consists of one-dimensional digital filters and delay lines. For one-dimensional digital filter(1D DF) case, once filter coefficients are represented by canonical signed digit formats, multiplications are exected by hardwired-shifting methods. The related bit numbers are handled to prevent picture quality degradation and pipelined adder architectures are adopted in each tap and output stage to speed up the filter. For delay line case, line-sharing DRAM is adopted to improve power dissipation and speed. The filter layout is designed by semi/full custom methods considering regularity and speed improvement, and normal operation is confirmed by simulation.