• 제목/요약/키워드: irregular wave

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A Study on the International Competitiveness of the Korea Liner Shipping Commany (우리나라 정기선사의 국제경쟁력에 관한 연구)

  • Lee, Jae-Kyu
    • Korean Business Review
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    • v.11
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    • pp.365-384
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    • 1998
  • Under the rapid change of the world shipping industry, the liner shipping company in Korea should initiate the adaptation power, counterplot for survival, and continuous development. The world shipping industry is in the middle of the wave for the liberalization and openness of it. According to this change in world shipping industry, it is the fact that government policy for shipping industry should start turning its direction from the protectionism to the liberalism. Under this kinds of situations, this study firstly treated the liner shipping company and its governmental policy of Korea and Japan. Based on those studies, analysis of the liner shipping company operation and management reality was executed. Through the execution of studies, the problems which should be solved for development occurred. Furthermore, this thesis takes two way of researches of literature and actual proof for reinforcement plan of international competitiveness. This standard time period of study is set in 1993 except the irregular liner shipping company.

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Development and Application of Dynamic Water Quality Model in Nakdong River (동적수질해석모형의 개발과 낙동강에의 적용)

  • Kwon, Na-Young;Choi, Hyun-Gu;Yu, Jae-Jung;Han, Kun-Yeun
    • Journal of Korea Water Resources Association
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    • v.43 no.3
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    • pp.283-294
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    • 2010
  • The objective of this study is to develop an accurate and stable dynamic water quality model which is capable of reflecting various flows and irregular cross sections and handling numerical oscillations under the low flow conditions. In order to solve the oscillation problem under the low flow conditions, diffusive wave method was applied to the low flow condition in developing a hydraulic model, DyHYD. DyQUAL is also developed as a water quality model to calculate up to 12 water quality variables including autochthonous BOD, water temperature, DO, TN and TP. The developed model is applied to both hypothetical river channels and actual Nakdong river watershed. Additionally, the applicability and reliability of the models are verified by comparing simulation results with observed values. Nash-Sutcliffe coefficients are estimated by comparison between simulation results and observed values. In the calibration and verification process, the coefficients varies from 0.391 to 0.591 and 0.704 to 0.902 for discharge, BOD, TN and TP, respectively.

Atrial Fibrillation Pattern Analysis based on Symbolization and Information Entropy (부호화와 정보 엔트로피에 기반한 심방세동 (Atrial Fibrillation: AF) 패턴 분석)

  • Cho, Ik-Sung;Kwon, Hyeog-Soong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.5
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    • pp.1047-1054
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    • 2012
  • Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice, and its risk increases with age. Conventionally, the way of detecting AF was the time·frequency domain analysis of RR variability. However, the detection of ECG signal is difficult because of the low amplitude of the P wave and the corruption by the noise. Also, the time·frequency domain analysis of RR variability has disadvantage to get the details of irregular RR interval rhythm. In this study, we describe an atrial fibrillation pattern analysis based on symbolization and information entropy. We transformed RR interval data into symbolic sequence through differential partition, analyzed RR interval pattern, quantified the complexity through Shannon entropy and detected atrial fibrillation. The detection algorithm was tested using the threshold between 10ms and 100ms on two databases, namely the MIT-BIH Atrial Fibrillation Database.

Harbor Tranquility Analysis with the Reflection-Transmission Boundary Condition of Floating Breakwaters (부유식 방파제의 반사-투과 경계조건을 적용한 항만 정온도의 해석)

  • 전인식;최민호;심재설;오병철
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.1
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    • pp.76-85
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    • 2002
  • The floating breakwater generally has an excellent water exchanging capability, but with some lowering harbor tranquility due to the wave transmission underneath floating body. In the initial stage of design, it is thus required to investigate several alternatives of breakwater layout for their performance of harbor tranquility. The present study aims to formulate a sort of reflection-transmission boundary condition of floating breakwater so that the existing numerical method using time dependent mild slope equation can still be applied to the case of floating breakwaters. The two and three dimensional tests were each performed to demonstrate the performance of the boundary condition. It was found that the reflection and transmission characteristics around the breakwater were well reproduced by the boundary condition. Finally, the reflection-transmission boundary condition were applied to a floating breakwater installed in an imaginary harbor with an irregular shape and bottom topography. The results surely showed that the present numerical method can effectively used in practical works related to the real sea construction of floating breakwaters.

Failure Case Studies of Sensors for Electronic Controlled Engine in LPG Vehicle (LPG 자동차에서 전자제어엔진용 센서의 고장사례에 관한 연구)

  • Kim, Chung-Kyun;Lee, Il-Kwon
    • Journal of the Korean Institute of Gas
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    • v.14 no.4
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    • pp.56-62
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    • 2010
  • The purpose of this paper analyzes and investigates the failure case studies of electronic control sensors for a LP gas engine. The malfunction of crank angle sensor, which controls a fuel injection volume of LP gas, displays an irregular and non-uniform pulse wave form. The pulse form, which is related to the noise of the crank angle sensor, displays at the rectangular peak with a saw-toothed shape and is intermittently generated with a level of 2.46V noise signal. The malfunction of No. 1 TDC sensor in which is caused from the internal disorder affects to the reduction of engine power and engine stop suddenly. If the malfunction of oxygen sensor is occurred due to a wiring problem of a sensor connector, the LP gas vehicle may produce a shaking and disharmony of an engine because of no signal supply from the oxygen sensor. The air cleaner replica produces the clogging of continuous supply of fresh air. This may cause the retardation of vehicle acceleration and engine disharmony intermittently.

Effects of Pilocarpine and Kainic Acid on EEG and Behavior Activity in Freely Behaving Rats

  • Choi, Byung-Ju;Cho, Jin-Hwa;Lee, Maangee-G.
    • Biomolecules & Therapeutics
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    • v.4 no.2
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    • pp.167-173
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    • 1996
  • This study was undertaken to evaluate a behavior-electroencephalogram (EEG) pattern relationship in pilocarpine- and kainic acid-induced convulsions of rats. Also we intended to examine the effect of a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, and diazepam on the pilocarpine-induced behavioral and electrical seizures in rats. The electrical activities at frontal and hippocampal areas and behavior activities were measured in freely moving rats. At the beginning of the experiments, the rats displayed an exploratory behavior. This awake and moving phase with a low amplitude, irregular, 4-10 Hz wave was followed by a still phase. Pilocarpine (400 mg/kg, i.p.) and kainic acid (0.5 mg/kg, i.c.v.) induced tonic and clonic seizures. The pilocarpine-induced change in electrical activities exhibited a weak correlation with behavioral convulsion at all stages. The amplitude and duration of the electrical response were not linear with the degree of behavioral score. An application of MK-801 (dizocilpine, 7.5 mg/kg) did not affect the amplitudes of the convulsant-induced electrical activities, though the same dose of this drug caused the deformation of the electrical pattern. There was no effect of MK-801 on the behavioral and electrical activities as expected. Diazepam (1 mg/kg) did not affect the amplitude of the electrical activities induced by pilocarpine but changed the pattern of these activities. Our study shows that there is no linear relationship between degree of behavior and amplitude of electrical activities of convulsants. This may indicate that the NMDA receptor stimulation can be processed by the neocortical or hippocampal network in a different way between behavioral and electrical activities.

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HEALING PROCESS OF DENTAL HARD TISSUES AND PULP TISSUE AFTER LASER IRRADIATION (레이저에 의해 손상된 치아경조직 및 치수조직의 치유과정에 대한 연구)

  • Kim, Chul-Soon;Min, Byung-Soon;Choi, Ho-Young;Park, Sang-Jin;Choi, Gi-Woon
    • Restorative Dentistry and Endodontics
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    • v.23 no.1
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    • pp.20-42
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    • 1998
  • The present study was designed to understand the basic principles of the laser system and to assess the optimal coditions of the Nd:YAG laser irradiation system in order to expand the use of the laser system in the dental field. The laser system used in this study was a pulsed-wave output type and the power level is 9 watts. The incisors of developing rats were irradiated with the laser system explained above for 0.5, 1, and 2 seconds giving energy density 71, 167, and 215 J/$cm^2$ respectively. The rats were sacrificed just after irradiation or 10 minutes and 10 days after irradiation. The specimens were examined with the stereoscope, light microscope and transmission electron microscope. The results are as follows: 1. The tissue removal efficiency (depth of the cavity formed) is increased with the energy density after Nd:YAG laser irradiation. 2. The carbonized area is increased with the energy density. Cracks and melted appearance are seen in all kinds of the energy densities. 3. The lacunae in the damaged alveolar bone by the laser irradiation were empty, while those in the newly formed bone were occupied with the osteocytes. The damaged alveolar bone was repaired by the osteoblasts and macrophages on the periphery of the bone matrix. 4. The damaged enamel was replaced by the loose connective tissues showing many kinds of cells. The ameloblasts were differntiated on the replaced loose connective tissue. 5. The damaged dentin was repaired by the irregular dentin formed by the odontoblasts differentiated from the mesenchymal cells migrated from the pulp core.

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Effect of natural frequency modes on sloshing phenomenon in a rectangular tank

  • Jung, Jae Hwan;Yoon, Hyun Sik;Lee, Chang Yeol
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.3
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    • pp.580-594
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    • 2015
  • Liquid sloshing in two-dimensional (2-D) and three-dimensional (3-D) rectangular tanks is simulated by using a level set method based on the finite volume method. In order to examine the effect of natural frequency modes on liquid sloshing, we considered a wide range of frequency ratios ($0.5{\leq}fr{\leq}3.2$). The frequency ratio is defined by the ratio of the excitation frequency to the natural frequency of the fluid, and covers natural frequency modes from 1 to 5. When fr = 1, which corresponds to the first mode of the natural frequency, strong liquid sloshing reveals roof impact, and significant forces are generated by the liquid in the tank. The liquid flows are mainly unidirectional. Thus, the strong bulk motion of the fluid contributes to a higher elevation of the free surface. However, at fr = 2, the sloshing is considerably suppressed, resulting in a calm wave with relatively lower elevation of the free surface, since the waves undergo destructive interference. At fr = 2, the lower peak of the free surface elevation occurs. At higher modes of $fr_3$, $fr_4$, and $fr_5$, the free surface reveals irregular deformation with nonlinear waves in every case. However, the deformation of the free surface becomes weaker at higher natural frequency modes. Finally, 3-D simulations confirm our 2-D results.

Comparative Experimental Study on Sloshing Impact Loads of LNG Cargoes in Membrane Containment System of 160K LNGC (160K LNGC 멤브레인 화물창에 작용하는 슬로싱 충격 하중에 대한 비교 실험 연구)

  • Kwon, Chang Seop;Lee, Young Jin;Kim, Hyun Joe;Lee, Dong Yeon
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.2
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    • pp.103-108
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    • 2019
  • A new state-of-the-art sloshing research equipment has developed to perform the model test of LNG tanks for the safer design of LNG cargo containment system in violent sloshing phenomena. This sloshing test system has developed by the Samsung Ship Model Basin (SSMB) and thoroughly verified. The accuracy of the motion of hexapods equipment for the excitation of a model tank has been verified. The maximum displacement in six degrees of freedom, harmonic motions of various frequencies, and irregular motions in wave conditions are measured and compared with input signals. In order to confirm the reliability of the post-processing program for measured impact pressure, the post-processed results were compared with those of the reference institute. A benchmarking sloshing test using 1/50 scale model of 160K LNGC tank was conducted for the verification of the whole testing system. The partial filing levels were considered. As a result of the experiment, it is confirmed that the results are in good agreement with those of the reference institute.

The Analysis of the Maison Margiela's Design Code -Focusing on the Checklist Method- (메종 마르지엘라의 디자인 코드 분석 -체크리스트법을 중심으로-)

  • Mok, So-Ri;Cho, Jean-Suk
    • Journal of Fashion Business
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    • v.19 no.4
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    • pp.135-152
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    • 2015
  • The purpose of this study is to explore the role of deconstruction and creative destruction in Maison Margiela’s fashion design code, which has opened the door to a new wave of innovative design since 1988. Using a combination of theoretical analysis, precedent research, and a review of existing literature, five years of Maison Margiela's works (2010-2014) were evaluated. The analysis shows that Maison Margiela’s Design Code consists of the following key elements: Addition, Extension, Asymmetry, Elimination, Deconstruction, Complanation, and Inversion. Addition refers to act of attaching additional pieces of fabric or clothing on the existing piece. Extension refers to the act of extending the design elements, such as their position or features. Asymmetry means the irregular positioning of left-to right and front-to-back length and features. Deconstruction could be seen in intentionally frayed sleeves, open seams, and tears in the cloth. The element of Elimination was evident in the removal of key pieces of clothing such as a coat, pants, blouse, and a jacket. Complanation refers to the reversion to a two dimensional contemplation of the human form rather than the more obvious 3-dimensional form. Finally, Inversion was used by displaying an inner layer of clothing on the outside or exposing seams or zippers in a way that people are not accustomed to seeing. It also meant that the order of wearing clothes was sometimes inverted, so external layers would be worn within clothing that are traditionally underneath. Maison Margiela’s creations represented a break