• The Journal of the Acoustical Society of Korea
• /
• v.38 no.6
• /
• pp.670-677
• /
• 2019

As the presence of background noise in acoustic signal degrades the performance of speech or acoustic event recognition, it is still challenging to extract noise-robust acoustic features from noisy signal. In this paper, we propose a combined structure of Wasserstein Generative Adversarial Network (WGAN) and MultiTask AutoEncoder (MTAE) as deep learning architecture that integrates the strength of MTAE and WGAN respectively such that it estimates not only noise but also speech features from noisy acoustic source. The proposed MTAE-WGAN structure is used to estimate speech signal and the residual noise by employing a gradient penalty and a weight initialization method for Leaky Rectified Linear Unit (LReLU) and Parametric ReLU (PReLU). The proposed MTAE-WGAN structure with the adopted gradient penalty loss function enhances the speech features and subsequently achieve substantial Phoneme Error Rate (PER) improvements over the stand-alone Deep Denoising Autoencoder (DDAE), MTAE, Redundant Convolutional Encoder-Decoder (R-CED) and Recurrent MTAE (RMTAE) models for robust speech recognition.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1998.10a
• /
• pp.210-221
• /
• 1998

In the period from the year 1500 to 1980. at least 14 large earthquake with epicenters in the northeastern China and Yellow Sea were felt or destructive in the Korean Peninsula. The most sigmificant events among them were the 1668 July 25 Tancheng earthquake of mamnitude 8.5, and the 1975 Feb. 4 Haicheng earthquake of magnitude 7.3. The Haicheng earthquake of the year 1975 in am extraordinary one among those occurred in the northeastern China in the 20th century in the sense the Shake of the event affected all over the Korean Peninsula. The tremor was felt even at the southeastern tip of the Korea and northern part of Kyushu 700km far away from the epicenter. In order to see the variation and trend of the effect of the Haicheng earthquake on the Korean Peninsula, the two data sets of the northern and southern parts of the peninsula were merged into one combined data set. The spatial variation of intensity shows smooth decrease from the value 4 of the northwestern region near the source to the value 1 of the Cheju Island and Kjushu. However, there are four regions of locally high intensity value. They are the region along downstream of Abrok(Yalu) River with intensity 5, the region around Shinpo of intensity 4, the area comprising Seoul and Chuncheon Cities of intensity 4, and Pohang-Pusan area of intensity 3. We suppose that there might be three types of possible mechanisms. The first one is concerned with the lateral inhomogeneity of velocity in the crust caused by wide distribution of relatively fractured rock. The second one is related with reflections of surface waves caused by the crestal thinning effect at border regions of the Peninsular in contact with the Ulleung Basin and the Japan Basin. The third possibility is local site effect caused by thick Tertiary or Quaternary rocks and soil layers.

• Journal of The Korean Association of Information Education
• /
• v.14 no.3
• /
• pp.437-447
• /
• 2010

The purpose of this thesis was to design and develop an effective e-PBL(Problem-Based Learning) for cultivating consciousness of information and communication ethics. The proposed e-PBL is based on PBL which is one of the constructivism teaching-learning theories. Online learning and face-to-face classes were systematically combined for achieving the teaching-learning goals. And the main module for online learning run on Moodle, an open source learning management system. To examine educational effectiveness of the proposed e-PBL, an experimental study was conducted through the education content and method to the subject of two class in the second-grade of university located in OO city. For experiment 60 students(treatment group=30, control group=30) are participated. And they were randomly assigned to one of ten subgroups, comprising of six students, respectively. The results of this study showed that the education using proposed e-PBL is more effective in cultivating consciousness of information and communication ethics and learners responded positively than the education using traditional face-to-face PBL learning method.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.41 no.4
• /
• pp.176-180
• /
• 2015

Objectives: The increased prevalence of antibiotic resistance is an outcome of evolution. Most patients presenting with odontogenic space infections also have associated systemic co-morbidities such as diabetes mellitus resulting in impaired host defense. The present study aims to compare the odontogenic spaces involved, antibiotic susceptibility of microorganisms, length of hospital stay, and the influence of systemic comorbidities on treatment outcome in diabetic patients. Materials and Methods: A 2-year prospective study from January 2012 to January 2014 was conducted on patients with odontogenic maxillofacial space infections. The patients were divided into two groups based on their glycemic levels. The data were compiled and statistically analyzed. Results: A total of 188 patients were included in the study that underwent surgical incision and drainage, removal of infection source, specimen collection for culture-sensitivity, and evaluation of diabetic status. Sixty-one out of 188 patients were found to be diabetic. The submandibular space was the most commonly involved space, and the most prevalent microorganism was Klebsiella pneumoniae in diabetics and group D Streptococcus in the nondiabetic group. Conclusion: The submandibular space was found to be the most commonly involved space, irrespective of glycemic control. Empiric antibiotic therapy with amoxicillin plus clavulanic acid combined with metronidazole with optimal glycemic control and surgical drainage of infection led to resolution of infection in diabetic as well as nondiabetic patients. The average length of hospital stay was found to be relatively longer in diabetic individuals.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.8
• /
• pp.98-105
• /
• 2008

FlexRay is a high-speed communications protocol with high flexibility and reliability. It was devised by automotive manufacturers and semiconductor vendors and implemented as on vehicle LAN protocol using x-by-wire systems. FlexRay provides a high speed serial communication, time triggered bus and fault tolerant communication between electronic devices for automotive applications. In this paper, we first design the FlexRay communication controller, bus guardian protocol specification and function parts using SDL (Specification and Description Language). Then, the system is re-designed using Verilog HDL based on the SDL source. The FlexRay system was synthesized using Samsung $0.35{\mu}m$ technology. It is shown that the designed system can operate in the frequency range above 76 MHz. In addition, to show the validity of the designed FlexRay system, the FlexRay system is combined with automobile advance alarm system in vehicle applications. The FlexRay system is implemented using ALTERA Excalibur ARM EPXA4F672C3. It is shown that the implemented system operates successfully.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.1
• /
• pp.31-39
• /
• 2017

The effects of application of gypsum and fresh cattle manure on the yield of forage crop were investigated in Hwaong reclaimed land in Korea for 3 years from 2011 to 2013. This study was conducted to develop the practical application method of livestock manure as a fertilization source and a soil physico-chemical ameliorator for the cultivation of forage crop $Sorghum{\times}Sudangrass$ hybrid in newly reclaimed tidal land soil. Treatments with six applications were established with three replications; chemical fertilizer (CF), gypsum (G) $20Mg\;ha^{-1}$, G+fresh cattle manure (FCM) 100%, G+FCM 200%, G+FCM 300% and FCM 100% which referred to the application rate equivalent to the recommended amount of phosphate fertilization by soil test. The combined treatments of G+FCM increased soil organic matter, $Av.P_2O_5$ and exchangeable $Ca^{2+}$ contents while decreased exchangeable $Na^+$ and $Mg^{2+}$. The soil bulk density, soil hardness and soil aggregate formation were improved by G+FCM treatments. The dry matter yields of $Sorghum{\times}Sudangrass$ hybrid were significantly increased in proportion to the application rate of FCM. The phosphorus use efficiency showed the highest in the application level of G+FCM 100%, which seemed to be the results of reduced nutrient use efficiency by nutrient immobilization, leaching etc. when applied excessive amount of fresh animal manure.

• Nuclear Engineering and Technology
• /
• v.52 no.10
• /
• pp.2410-2414
• /
• 2020

Heavy ions have a high potential for destroying deep tumors that carry the highest dose at the peak of Bragg. The peak caused by a single-energy carbon beam is too narrow, which requires special measures for improvement. Here, carbon-12 (¹²C) ion with different energies has been used as a source for calculating the dose distribution in the water phantom, soft tissue and bone by the code of Monte Carlobased FLUKA code. By increasing the energy of the initial beam, the amount of absorbed dose at Bragg peak in all three targets decreased, but the trend for this reduction was less severe in bone. While the maximum absorbed dose per bone-mass unit in energy of 200 MeV/u was about 30% less than the maximum absorbed dose per unit mass of water or soft tissue, it was merely 2.4% less than soft tissue in 400 MeV/u. The simulation result showed a good agreement with experimental data at GSI Darmstadt facility of biophysics group by 0.15 cm average accuracy in Bragg peak positioning. From 200 to 400 MeV/u incident energy, the Bragg peak location increased about 18 cm in soft tissue. Correspondingly, the bone and soft tissue revealed a reduction dose ratio by 2.9 and 1.9. Induced neutrons did not contribute more than 1.8% to the total energy deposited in the water phantom. Also during ¹²C ion bombardment, secondary fragments showed 76% and 24% of primary 200 and 400 MeV/u, respectively, were present at the Bragg-peak position. The combined treatment of carbon ions with neutron or electron beams may be more effective in local dose delivery and also treating malignant tumors.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.6
• /
• pp.490-498
• /
• 2019

The intermittent electric power supply of renewable energy can have extremely negative effect on power grid, so long-term and large-scale storage for energy released from renewable energy source is required for ensuring a stable supply of electric power. Power to gas which can convert and store the surplus electric power as hydrogen through water electrolysis is being actively studied in response to increasing supply of renewable energy. In this paper, we proposed the novel concept of hydrogen liquefaction process combined with pre-cooling process using the liquid air. It is that hydrogen converted from surplus electric power of renewable energy was liquefied through the hydrogen liquefaction process and vaporization heat of liquid hydrogen was conversely recovered to liquid air from ambient air. Moreover, Comparisons of specific energy consumption (kWh/kg) saved for using the liquid air pre-cooling was quantitatively conducted through the performance analysis. Consequently, about 12% of specific energy consumption of hydrogen liquefaction process was reduced with introducing liquid air for pre-cooling and optimal design point of helium Brayton cycle was identified by sensitivity analysis on change of compression/expansion ratio.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.54 no.2
• /
• pp.94-100
• /
• 2005

Korea Electrotechnology Research Institute(KERI) has successfully developed a 100hp-1800rpm-class high temperature superconducting(HTS) motor with high efficiency under partnership with Doosan Heavy Industries & Construction Co. Ltd. This motor has a HTS field winding and an air-cooled stator. The advantages of HTS motor can be represented by a reduction of 50% in both losses and size compared to conventional motors of the same rating. The cooling system is based on the heat transfer mechanism of the thermosyphon by using GM cryocooler as cooling source. The cold head is in contact with the condenser of a Ne-filled thermosyphon. Independently, the rotor assembly was tested at the stationary state and combined with stator. The HTS field winding could be cooled into below 30K. Test of open-circuit characteristics(OCC) and short-circuit characteristics(SCC) and load test with resistive load bank were conducted in generator mode. Also, load tests in motor mode driven by inverter were finished at KERI. Maximum operating current of field winding at 30K was 120A. From OCC and SCC test results synchronous inductance and synchronous reactance were 2.4mH, 0.49pu, respectively. Efficiency of this HTS machine was 93.3% in full load(100hp) test. This paper will present design, construction. and experimental test results of the 100hp HTS machine.

• Journal of the Korean Electrochemical Society
• /
• v.16 no.3
• /
• pp.157-161
• /
• 2013

Porous $LiMn_{0.6}Fe_{0.4}PO_4$ (LMFP) was synthesized by a sol-gel process. Uniform dispersion of the conductive carbon source throughout LMFP with uniform carbon coating was achieved by heating a stoichiometric mixture of raw materials at $600^{\circ}C$ for 10 h. The crystal structure of LMFP was investigated by Rietveld refinement. The surface structure and pore properties were investigated by SEM, TEM and BET. The LMFP so obtained has a high specific surface area with a uniform, porous, and web-like nano-sized carbon layer at the surface. The initial discharge capacity and energy density were 152 mAh/g and 570 Wh/kg, respectively, at 0.1 C current density, and showed stable cycle performance. The combined effect of high porosity and uniform carbon coating leads to fast lithium ion diffusion and enhanced electrochemical performance.