• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.32-39
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• 1998

This paper presents the experimental results on the 3-electrode DC-PDP which has a common electrode to improve the PDP life cycle. The measured DC characteristic proves the effectiveness of common electrode absorbing about half of discharge currents. The waveforms for pulse memory operation of3-electrode PDP without crosstalk could also be determined from the I-V characteristics. The pulse memory drives of 8*8 cell array show the frequency response fo memory margin and the luminance efficiency of 3-electrode PDP are quite different from genrally known characteristics of 2-electrode DC-PDP.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.71-78
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• 1995

Based on the popular 4-transistor SRAM cell, an analytical expression of the minimum cell ratio was derived by modeling the static read operation. By analyzing the relatively simple expression for the minimum cell ratio, which was derived assuming the ideal transistor characteristics, effects of the changes in supply voltage and process parameters on the minimum cell ratio was predicted, and the minimum power supply voltage for read operation was determined. The results were verified by simulations utilizing the suggested simulation method, which is suitable for monitoring the lower limit of supply voltage for proper cell operation. From the analysis, it was shown that the worst condition for cell operation is low temperature and low supply voltage, and that the operation margin can be effectively improved by reducing the threshold voltage of the cell transistors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.88-92
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• 2009

Total pressure recovery ratio in intake is crucial factor to the operational characteristics of supersonic propulsion system because it does not compress inlet air mechanically by compressor, but does compress inlet air by ram compression. As the result of that the dynamic characteristic analysis of engine was performed before the controller was designed, it could be ascertained when the AoA of flight vehicle increases, the buzz margin decreases so that the shock wave produced outside intake in the specified area according to flight operation's characteristics. Therefore the PID control algorithm was designed to be controlled buzz margin that the characteristic of shock wave could meet the requirement of performance in intake. The PID controller was designed that the buzz margin value is being positive number using the control variables; fuel flow and nozzle throat area.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1981.05a
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• pp.39.3-40
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• 1981

Concerning the pathogenesis of acquired cholesteatoma in attic, there has been postulated theories by immigration from the Shrapnell's portion of the tympanic membrane, posterosuperior quardrant of the deep meatal skin and invagination of the margin of the central perforation. Otherwise, squamous metaplasia of the epithelium lining the middle ear cleft has been supported as a possible cause of cholesteatoma. Clinically, there has been known of the facts that cholesteatoma is formed in the attic but the pathogenesis concerning the acquired cholesteatoma is not still exactly reported. Recently, authors analyzed 170 cases of cholesteatomatous middle ear performed the operation to the middle ear cleft. On the operation finding, when the primary focus of the cholesteatoma was in the attic, we observed two types of perforation, marginal and central perforation in the Shrapnell's portion, and retraction to the Prussak's space, bony defect on the Rivinus notch. Among 36 cases of the cholesteatoma, the perforation of the Shrapnell's portion are 5 cases. Bony defect on the Rivinus notch and marginal perforation on the posterosuperior quadrant of the Shrapnell's portion are 21 cases. Among these cases, 3 cases are combined with central perforation of the Shrapnell's portion. Conclusively, the reasons that cholesteatoma is favorable site in the attic: 1) Excretion of the inflammatory discharge in the attic is difficult because of the distance of the E-tube. 2) The Shrapnell's portion has less collagen fiber than the pars tensa and it is thin because the elastic fibers are rich in it. It is easy to retract within the Prussak's space to the cases of keratinizing hyperplasia. 3) The epidermis attached at the Rivinus notch of the superior portion on the Shrapnell's portion is invaginated through the destructed bony wall of the Rivinus notch and the margin of the tympanic membrane in the response to the keratinizing hyperplasia.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.9
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• pp.707-714
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• 2016

This paper describes analysis results of vibration characteristics and modal test for a small-scale quad-rotor drone. The rotor arm has a slender body with a propeller and motor at its tip. Rotor system generates excitation for an unbalanced mass. Therefore, the drone platform is involved in the possibility of resonance. For advance identification of the possibility of resonance, confirmation of eigen-mode being closest to the propeller operation range is necessary. Material properties of CFRP tubes used for the rotor arm were acquired by finding the natural frequency based on Rayleigh method. A simplified quad-rotor FE model consisting of rotor arm assembly with tip mass was built to perform numerical analysis, and a free-free boundary condition was applied to provide flight status. Modal tests for the actual platform with impact hammer instrument were performed to verify analysis results. Separation margin from hazardous eigen-mode was checked on the propeller operation range.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.1
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• pp.27-35
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• 2023

Pressure tubes are the main components of PHWR core and serve as the pressure boundary of the primary heat transport system. However, because pressure tubes have changed their geometrical dimensions under the severe operating conditions of high temperature, high pressure and neutron irradiation according to the increase of operation time, all dimensional changes should be predicted to ensure that dimensions remain within the allowable design ranges during the operation. Among the deformations, the diameter expansion due to creep leads to the increase of bypass flow which may not contribute to the fuel cooling, the decrease of critical channel power and finally the deration of the power to maintain the operational safety margin. This study is focused on the modeling of the expansion of the pressure tube diameter based on the operating conditions and measured diameter data. The pressure tube diameter expansion was modeled using the neutron flux and temperature distributions of each fuel channel and each fuel bundle as well as the measured diameter data. Although the basic concept of the current modeling approach is simple, the diameter prediction results using the developed methodology showed very good agreement with the real data, compared to the existing methodology.

• Archives of Plastic Surgery
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• v.32 no.3
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• pp.397-402
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• 2005

For its lowerlid entropion correction, nonsurgical eyelid suture or surgical eyelid suture can be employed. Different types of surgical eyelid suture such as the Hotz method and the Callahan method, are generally performed, but were not sufficient for correcting of entropion. In our hospital we performed modified skin-tarsal fixation on 15 patients, 5 male and 10 female from January 20, 1999 to December 16, 2002. We corrected lower eyelid entropion with the excision of the skin and orbicularis oculi muscle and buried suture of tarsal plate and dermis which is a variant of the Callahan method. All the patients were satisfied with the operation results, and there was no case of recurrence of the lower eyelid pricking the cornea. During the 6 months period after the operation, the lower eyelids slightly turned inward but there was no further progression. The correction was performed excessively, therefore there was no case of recurrence after the operation and the results were satisfactory. There developed a dimple at the suture margin caused by skin contraction but it usually disappeared within 2 months after the operation. To avoid recurrence and to achieve satisfactory results, the orbicularis oculi muscle must be totally resected at the ciliary margin. We resected ciliary as well as pretarsal portion of orbicularis oculi muscle. Also, since most of the recurrences are originated from the medial side, the medial portion of skin flap must be tightly fixed to avoid recurrence and the upper part of the dermis should be fixed tightly to the lower border of the tarsal plate.

• Archives of Plastic Surgery
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• v.35 no.6
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• pp.663-668
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• 2008

Purpose: Pedicled transverse rectus abdominis myocutaneous(TRAM) flap has been a gold standard for breast reconstruction and one of surgical techniques preferred by many surgeons. The authors examined the course of deep epigastric artery focusing on distance from margins of rectus abdominis to pedicle and location of choke vessels to get minimal muscles during pedicled TRAM flap operation. Methods: Eleven rectus abdominis muscle from nine cadavers were used in this study. Rectus abdominis was separated from the cadavers, deep inferior and superior epigastric artery were isolated and then 8 anatomical landmarks in medial and lateral margins of rectus abdominis were designated. Distance to a pedicle meeting first horizontally was measured and vertical location from umbilicus to choke vessel was determined. In addition, 32 rectus abdominis images of 16 women(average age: 37.2 years old) from 64 channel abdomen dynamic computerized tomography were also examined with the same anatomical landmarks with those of cadavers. Results: Average distance from four landmarks on lateral margin of rectus abdominis to pedicle was 1.9 - 3.4cm and 1.8 - 3.8 cm on medial margin. Choke vessel was located between middle and inferior tendinous intersection in all cases and average distance between two tendinous intersection was 6.7 - 7.0 cm on medial margin and 6.2 cm on lateral margin. Location of inferior tendinous intersection was on umbilicus or superior of it in all cases and its average distance from umbilicus was 1.8 - 5.6 cm on medial margin and 2.7 - 6.2 cm on lateral margin. Conclusion: Distance from medial and lateral margins of rectus abdominis muscle to pedicle was the shortest in inferior tendinous intersection and that was averagely 1.8 cm on medial margin and 1.9 cm in average on lateral margin. All choke vessels were located between middle and inferior tendinous intersection.

• ETRI Journal
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• v.26 no.6
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• pp.583-588
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• 2004

In this paper we investigate the effect of a shield metal line inserted between adjacent bit lines on the refresh time and noise margin in a planar DRAM cell. The DRAM cell consists of an access transistor, which is biased to 2.5V during operation, and an NMOS capacitor having the capacitance of 10fF per unit cell and a cell size of $3.63{\mu}m^2$. We designed a 1Mb DRAM with an open bit-line structure. It appears that the refresh time is increased from 4.5 ms to 12 ms when the shield metal line is inserted. Also, it appears that no failure occurs when $V_{cc}$ is increased from 2.2 V to 3 V during a bump up test, while it fails at 2.8 V without a shield metal line. Raphael simulation reveals that the coupling noise between adjacent bit lines is reduced to 1/24 when a shield metal line is inserted, while total capacitance per bit line is increased only by 10%.

• Journal of Communications and Networks
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• v.10 no.3
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• pp.351-361
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• 2008

This paper presents a delay-margin based traffic engineering (TE) approach to provide end-to-end quality of service (QoS) in multi-protocol label switching (MPLS) networks using differentiated services (DiffServ) at the link level. The TE, including delay, class, and route assignments, is formulated as a nonlinear optimization problem reflecting the inter-class and inter-link dependency introduced by DiffServ and end-to-end QoS requirements. Three algorithms are used to provide a solution to the problem: The first two, centralized offline route configuration and link-class delay assignment, operate in the convex areas of the feasible region to consecutively reduce the objective function using a per-link per-class decomposition of the objective function gradient. The third one is a heuristic that promotes/demotes connections at different links in order to deal with concave areas that may be produced by a trunk route usage of more than one class on a given link. Approximations of the three algorithms suitable for on-line distributed TE operation are also derived. Simulation is used to show that proposed approach can increase the number of users while maintaining end-to-end QoS requirements.