• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.50 no.11
• /
• pp.537-545
• /
• 2001

This paper describes the analysis of sheath circulating current and various methods to reduce the large circulating current in case of operating cable system using EMTP/ATPDraw. And also, possible methods are proposed through a detailed analysis regarding cable systems by considering various electrical and environmental factors. It is evaluated that the proposed reduction methods can be effectively applied to reduce the large sheath circulating over current with the minimized electrical problems.

• Journal of the Society of Naval Architects of Korea
• /
• v.50 no.3
• /
• pp.182-189
• /
• 2013

In the development process of new naval ships, it is necessary to make the effort of the signature management and reduction of ship infrared(IR) signature to increase the ship survivability(susceptibility). So far the ship's contrast radiant intensity is used as a ship IR signature design criteria during the naval ship design stages. However, nowaday it is in a state of disorder at the basic design stage because of the lack of any related studies and methods. In this study, the IR signature management methods for improving the signature reduction and ship survivability are suggested by the comparison analysis of the advantages and disadvantages of signature management techniques. And also the criteria for the ship signature management are suggested when considering the infrared signature measuring assets and sea trial environments of the Korean peninsula.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.10B
• /
• pp.1921-1936
• /
• 1999

In this paper, we analyze the blocking artifact in block transform-coded images and propose a classification algorithm which classifies each horizontal and vertical block boundary into four regions of EQ, BA, EE, and AE according to the characteristics of the blocking artifact. We also compare the performance of several blocking artifact reduction methods which can reduce blocking artifact in block transform-coded images well. As the blocking artifact reduction methods, the LOT, Kim's wavelet transform-based method, Yang's POCS, Paek's POCS, and Jang's CM have been selected. Experimental results show that each horizontal and vertical block boundary classified by using the proposed classification algorithm yields different characteristics of discontinuities due to the blocking artifact according to the classified region. It is also shown that the blocking artifact reduction methods using wavelet transform yield better performance over the other methods.

• The Korean Journal of Applied Statistics
• /
• v.28 no.5
• /
• pp.991-1001
• /
• 2015

Digital images acquired by digital devices are used in many fields. Applying statistical methods to the processing of images will increase speed and efficiency. Methods to remove noise and image quality have been researched as a basic operation of image processing. This paper proposes a novel reduction method that considers the direction and magnitude of the edge to remove image noise effectively using statistical methods. The proposed method estimates the brightness of pixels relative to pixels in the same direction based on a robust regression model. An estimate of pixel brightness is obtained by weighting the magnitude of the edge that improves the performance of the average filter. As a result of the simulation study, the proposed method retains pixels that are well-characterized and confirms that noise reduction performance is improved over conventional methods.

• Archives of Craniofacial Surgery
• /
• v.10 no.1
• /
• pp.33-36
• /
• 2009

Purpose: Fractures of the mandibular condylar area are common injuries that account for 29% to 40% of fractures of the facial bones and represent 20% to 62% of all mandibular fractures. Currently 3 main methods are being used in the treatment of mandibular subcondylar fractures: closed reduction; open reduction and internal fixation; Endoscopic reduction and internal fixation. Each method has its proponents and opponent as well as advantages and disadvantages, and indications for each vary among surgeons. There are six approaches of open reduction: submandibular, retromandibular, preaurilcular, postauricular, intraoral, transparotid approach. Among them, transparotid approach has been described for subcondylar exposure with dissection in the direction of facial nerve fibers to expose the bone through the parotid gland. This approach carries the risk of a parotid glandular fistula as well as facial nerve injury but has the advantage of being directly over the fracture site. We report safety and efficacy of surgical treatment using a transparotid approach for direct plating. Methods: A 43-year-old man sustained multiple facial bone fractures by driver traffic accident. Mandibular subcondyle was fractured and dislocated internally. We performed open reduction and internal fixation by transparotid approach. Fractured site was fixed by titanium mini plate & screw. We applicated arch bar for approximately 3 weeks. Results: Follow-up length was about 5months. Scar of surgical incision was indistinct, there was no symptoms and signs of facial nerve and parotid gland injury, and maximal mouth opening was measured 49.5 mm. Conclusion: Transparotid approach has high risks of facial nerve and parotid gland injury, but paradoxically it is the most effective technique in saving facial nerve. Open reduction and internal fixation of mandibular subcondylar fracture by transparotid approach with precise and versed procedure, best outcome can be expected.

• Journal of Korean Biological Nursing Science
• /
• v.9 no.2
• /
• pp.118-124
• /
• 2007

Purpose: The purpose of this study was to compare three surgical scrub methods-4% chlorhexidine gluconate(CHG) with brush, 4% CHG without brush, and waterless scrub using 1% CHG and 61% ethanol combination(alcohol-based agent)-for antimicrobial efficacy. Method: "Glove-juice technique" was used to evaluate microbial hand counts before surgical scrubs, 1 min and 3 hr after surgical scrubs. Result: Waterless scrub using CHG and ethanol combination resulted in a 4.8-log reduction at 1 min and 4.0-log reduction at 3 hr. CHG without brush resulted in a 4.7-log reduction at 1 min and 3.3-log reduction at 3 hr. The traditional scrub using CHG with brush resulted in a 3.6-log reduction at 1 min and 0.8-log reduction at 3 hr. The waterless scrub and CHG without brush showed significantly higher log reduction(p<.05) than CHG with brush at 1 min and 3 hr after surgical scrub. Waterless scrub showed greater log reductions than CHG without brush, but there was no statistical difference between the two groups. Conclusion: Waterless scrub using alcohol-based agent showed more persistent and immediate antimicrobial efficacy than either CHG with brush or CHG without brush.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.5
• /
• pp.649-655
• /
• 2022

In this paper, a determinant-based two-channel noise reduction method which utilizes speech presence probability (SPP) is proposed. The proposed method improves noise reduction performance from the conventional determinant-based two-channel noise reduction method in [7] by applying SPP to the Wiener filter gain. Consequently, the proposed method adaptively controls the amount of noise reduction depending on the SPP. For performance evaluation, the segmental signal-to-noise ratio (SNR), the perceptual evaluation of speech quality, the short time objective intelligibility, and the log spectral distance were measured in the simulated noisy environments considered various types of noise, reverberation, SNR, and the direction and number of noise sources. The experimental results presented that determinant-based methods outperform phase difference-based methods in most cases. In particular, the proposed method achieved the best noise reduction performance maintaining minimum speech distortion.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.12 no.1
• /
• pp.37-49
• /
• 2004

Four different data reduction methods for the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two heat and mass transfer models and two fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the reduced heat transfer coefficients revealed that the single potential heat and mass transfer model yielded the humidity-independent heat transfer coefficients. Two fin efficiency models-enthalpy model and humidity model-yielded approximately the same fin efficiencies, and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.577-581
• /
• 2006

In this study, it is presented a vibration cause of an electronic forklift by a variable excitation through experimental methods. It is presented a vibration influence by a variable excitation and established an FE model about structure vibration. It is used an FE model and presented parameters causing the vibration. It is presented a mechanism causing the vibration of the electronic forklift and proposed a vibration reduction of the electronic forklift.

• Communications for Statistical Applications and Methods
• /
• v.22 no.3
• /
• pp.305-312
• /
• 2015

We extend a generalized partially linear single-index model and newly define a generalized partially double-index model (GPDIM). The philosophy of sufficient dimension reduction is adopted in GPDIM to estimate unknown coefficient vectors in the model. Subsequently, various combinations of popular sufficient dimension reduction methods are constructed with the best combination among many candidates determined through a bootstrapping procedure that measures distances between subspaces. Distinguishing values are newly defined to match the estimates to the corresponding population coefficient vectors. One of the strengths of the proposed model is that it can investigate the appropriateness of GPDIM over a single-index model. Various numerical studies confirm the proposed approach, and real data application are presented for illustration purposes.