• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.261-271
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• 2016

In the prediction of response of a pile in soil, numerical approaches such as a finite element method are generally applied due to complicate nonlinear behaviors of soils. However, the numerical methods based on the finite elements require heavy efforts in pile and soil modelling and also take long computing time. So their usage is limited especially in the early design stage in which principal dimensions and properties are not specified and tend to vary. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to model and take short computing time. Therefore, if they are validated to be reliable, they would be applicable in predicting responses of a pile in soil, particularly in early design stage. In case of wind turbines regarded in this study, it is required to assess their natural frequencies in early stages, and in this simulation the supporting pile inserted in soil could be replaced with a simplified elastic boundary condition at the bottom end of the wind turbine tower. To do this, analysis for a pile in soil is performed in this study to extract the spring constants at the top end of the pile. The pile in soil can be modelled as a beam on elastic spring by assuming that the soils deform within an elastic range. In this study, it is attempted to predict pile deformations and influence factors for lateral loads by means of the beam-on-spring model. As two example supporting structures for wind turbines, mono pile and suction pile models with different diameters are examined by evaluating their influence factors and validated by comparing them with those reported in literature. In addition, the deflection profiles along the depth and spring constants at the top end of the piles are compared to assess their supporting features.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.139-148
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• 2006

The dynamic characteristics of a bridge deduced by using the modeling techniques depend on its stiffness and mass calculated from its geometric model. This research develops the FE modeling techniques for a steel plate girder bridge with composite section. and proves their validity by comparing the results with those from actual measurement. The FE modeling techniques are divided into two categories--a simplified one and two-dimensional model and a detailed three-dimensional model. In the meantime, the dynamic responses of the bridge tested for this research were measured by the ambient vibration some of accelerometers were been attached to its upper slab girder under normal traffic load. The Cross Power Spectrum obtained from the measurement was used to analyze the dynamic characteristics by natural excitation techniques. The analytic results are compared to those of each FE modeling, and thereby the modeling techniques were proved to be valid.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.265-271
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• 1999

Patients with mediastinal teratoma are usually asymptomatic, but may develop symptoms by rupture into adjacent structures which result in pneumonia, hemoptysis, pleural effusion, pericardial effusion, or pneumothorax. Rarely, life-threatening acute respiratory distress require a emergency surgery. Rupture into pleural cavity may result in pleuritis and pleural effusion with severe anterior chest or back pain. The symptom must be differentiated from other common intrathoracic distress diseases. Clinical, cytologic and radiologic examinations of pleural effusion, and moreover, measurement of enzymes such as amylase or insulin, which is secreted from pancreatic tissues, in pleural effusion and cystic fluid enabled us to make the diagnosis of rupture of mediastinal teratoma preoperatively.

• Proceedings of the Korean Society for Language and Information Conference
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• 2001.06a
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• pp.97-109
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• 2001

이 논문은 영어와 한국어에서 나타나는 완수동사(Accomplishment Verb)와 지속부사구(durative adverbial)의 상호작용에 대해서 논한다. Smith(1991)에 의하면 완수동사가 지속부사구와 결합하면, 동사와 부사구의 의미적 자질의 충돌을 피하기 위해서 완수동사의 상변환(Apsect Shift)이 일어난다. 본 논문은 이 상변환이 영어와 한국어에서 어떻게 실현되는가를 보이고, 이를 형식의미론에서 어떻게 기술할 수 있는가를 논한다. 완수동사가 지속부사구와 결합할 때, 영어와 한국어 모두에서 닫힌 완료 관점(closed perfective viewpoint)에서 열린 관점(open viewpoint)으로 관점 변환(viewpoint shift)이 일어난다. 그러나, 한국어의 상변환과 영어의 상변환이 완전히 일치하는 것은 아니다. 한국어의 관점변환은 완료관점도 아니고 미완료 관점도 아닌, 중립관점(neutral viewpoint)으로의 변환인 반면, 영어의 관점변환은 단순히 미완료 관점으로의 변환임이 논의된다. 이 주장은 한국어의 관점변환 구문은 이질적인 다수 사건의 연속 해석(heterogeneous sequential reading of multiple events)을 허용하는 반면, 영어의 관점변환구문은 오직 동질적인 단일 사건의 동시 해석 (homogeneous simultaneous reading of a single event)만을 허용한다는 사실에 의해서 지지 된다. 본 논문은 완수동사가 지속부사구와 결합할 때 일어나는 상변환에 대한 형식의 미론 분석을 Heim ＆ Kratzer (1998)의 틀에서 제시한다. 닫힌 관점에서 열린 관점으로의 상변환은 비가시적 시제 서법 운용자(covert temporal-modal operator)인 IMP를 지속부사구의 논항으로 설정하여 설명한다. IMP는 Dowty (1979)에서 미완료상의 모순(imperfective paradox)을 해결하기 위해서 설정한 PROG를 Heim ＆ Kratzer (1998)의 틀에 맞게 수정한 것이다. IMP는 평가 세계 (evaluation world)를 현실 세계(actual world)에서 가상 관성 세계(possible inertia would)로 변화시켜서, 완수동사의 종결점(ending point)을 현실세계에서 가상의 미래 세계로 움직이는 역할을 한다. 결과적으로, IMP는 완수동사의 닫힌 완료 관점을 현실세계에서는 열린 미완료 관점으로 변환시키되, 가상 관성 세계에서는 그대로 닫힌 관점으로 유지 시키는 효과를 가진다. 한국어와 영어의 관점 변환 구문의 차이는 각 언어의 지속부사구의 어휘 목록의 전제(presupposition)의 차이로 설명된다. 본 논문은 영어의 지속부사구는 논항의 하위간격

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.249-258
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• 2021

Bitcoin prices have been soaring recently as investors flock to cryptocurrency exchanges. The purpose of this study is to predict the Bitcoin price using a deep learning model and analyze whether Bitcoin is profitable through investment strategy. LSTM is utilized as Bitcoin prediction model with nonlinearity and long-term memory and the profitability of MA cross-over strategy with predicted prices as input variables is analyzed. Investment performance of Bitcoin strategy using LSTM forecast prices from 2013 to 2021 showed return improvement of 5.5% and 46% more than market price MA cross-over strategy and benchmark Buy & Hold strategy, respectively. The results of this study, which expanded to recent data, supported the inefficiency of the cryptocurrency market, as did previous studies, and showed the feasibility of using the deep learning model for Bitcoin investors. In future research, it is necessary to develop optimal prediction models and improve the profitability of Bitcoin investment strategies through performance comparison of various deep learning models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5939-5946
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• 2013

The bridge approach slabs (BAS) to provide a transitional roadway between a roadway pavement and a bridge structure have not performed adequately due to various factors. The current Korean Roadway Design Guidelines treat the BAS as a simply supported beam with 70% of the span length and do not consider settlement and void development underneath the slab. To investigate the effect of soil settlements on the bending moment of BAS, a beam on elastic support (BAS-ES) was used in the present study. The parameters used in this study were span length, washout length, washout location, and soil modulus. It was shown from the parametric study that washout regions closer to the midspan exhibit maximum moment in the slab. Since voids under the BAS have typically been observed to be closer to bridge abutments, the springs from the abutment were removed to simulate settlement and void development in the model. The design moments based on AASHTO LRFD Bridge Design Specifications were compared to those of Korean Standard Specifications for Highway Bridge and Design Trucks for Highway Bridges. Even if the design moment from BAS-ES was used to incorporate the effect of the potential washout, significant savings could still be achieved compared to the current BAS design.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.480-490
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• 2016

As wind turbines become larger and lighter, they are likely to respond sensitively by dynamic loads applied on them. Since the responses at resonances are particularly interested, it is required to be able to predict natural frequencies of wind turbines reliably at early design stage. To achieve this, the foundation-soil analysis is needed to be carried out and a finite element approach is adopted in general. However, the finite element approach would not be appropriate in early design stage because it demands heavy efforts in pile-soil modelling and computing facilities. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to handle. Therefore, they would be a useful tool in predicting a pile-soil interaction, particularly in early design stage. In this study an analysis for a pile inserted in soil is performed. The pile and soil are modelled as a beam and continuum medium, respectively, within an elastic range. In this analysis, influence factors at the pile head for lateral loads are predicted by means of this continuum approach for various length-diameter ratios of the pile. The influence factors predicted are validated with those reported in literature, proposed from a finite element analysis.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.199-208
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• 2010

In order to substitute FRP bar for steel bar in new structures, it is necessary to establish a reliable design code. But relatively little research has been conducted on the material in Korea. So, a total of 22 beam specimens (18 GFRP reinforced concrete and 4 conventional steel reinforced concrete) were constructed and tested. In the first phase of the experiment, it was carried out to observe flexural behavior, and collect deflection and crack data. In order to eliminate of the uncertainty by the shear reinforcements and induce flexural failure mode, any stirrup were not used and only shear span-depth ratio were adjusted. However, almost beams were broken by shear and the ACI 440.1R, CSA S806, which were used to design test beams, showed considerable deviation between prediction and test results of shear strengths. Therefore in the second phase of the study, shear failure modes and behavior were observed. A standard specimen had dimensions of 3,300 mm long ${\times}$ 800 mm wide ${\times}$ 200 mm effective depth. Clear span and shear span were 2,800 mm, 1,200 mm respectively. Control shear span-depth ratio was 6.0. Four-point bending test over simple support was conducted. Variables of the specimens were concrete compressive strength, type and elastic modulus of reinforcement, shear span-depth ratio, effective reinforcement ratio, the effect of bundle placing method and cover thickness.

• Management & Information Systems Review
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• v.39 no.2
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• pp.17-37
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• 2020

The purpose of this study is to investigate the global spillover effects through the existence of linear and nonlinear causal relationships between the US, European and BRIC financial markets after the period from the introduction of the Euro, the financial crisis and the subsequent EU debt crisis in 2007~2010. Although the global spillover effects of the financial crisis are well described, the nature of the volatility effects and the spread mechanisms between the US, Europe and BRIC stock markets have not been systematically examined. A stepwise filtering methodology was introduced to investigate the dynamic linear and nonlinear causality, which included a vector autoregressive regression model and a multivariate GARCH model. The sample in this paper includes the post-Euro period, and also includes the financial crisis and the Eurozone financial and sovereign crisis. The empirical results can have many implications for the efficiency of the BRIC stock market. These results not only affect the predictability of this market, but can also be useful in future research to quantify the process of financial integration in the market. The interdependence between the United States, Europe and the BRIC can reveal significant implications for financial market regulation, hedging and trading strategies. And the findings show that the BRIC has been integrated internationally since the sub-prime and financial crisis erupted in the United States, and the spillover effects have become more specific and remarkable. Furthermore, there is no consistent evidence supporting the decoupling phenomenon. Some nonlinear causality persists even after filtering during the investigation period. Although the tail distribution dependence and higher moments may be significant factors for the remaining interdependencies, this can be largely explained by the simple volatility spillover effects in nonlinear causality.

• Korean Journal of Psychosomatic Medicine
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• v.6 no.2
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• pp.147-154
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• 1998

Objective : This study was designed to find the characteristics of MMPI that could influence the outcome of cognitive behavioral therapy(CBT) for panic disorder. Methods : 34 patients who met DSM-IV criteria for panic disorder with or without agoraphobia had completed 11 weekly sessions of cognitive behavioral therapy. All the patients were assessed with MMPI before the initiation of treatment. Five self-report measures including Beck Depression Inventory(BDI), Spielberger State-Trait Anxiety Inventory(STAI), Agoraphobic Cognition Questionnarie(ACQ), Body Sensation Questionnaire(BSQ), and Daily Anxiety Selfrating (0 - 8 scales) were also assessed as a pre- and post-treatment assessment. After the completion of treatment, patients were classified by the High End-State(HES) functioning group and the Low End-State(LES) functioning group for the data analysis. Results : 1) The LES group showed significantly higher scores in Hypochondriasis Scale(HS), Depression Scale(D), Hysterical Scale(Hy), Obsessive Scale(Pt), Schizophrenia Scale(Sc) and Validity Scale(F) of MMPI than the HES group. However, these differences gave impressions that the LES group had more severe symptoms rather than that they could be the factors influencing the outcome of CBT. 2) Though, the severity of symptoms of the LES group in the 5 measures of pre-assessment was basically higher than that of the HES group. The fact that both group showed the similar improvement between pre- and post-assessment supported the above interpretation. Conclusion : In regarding the above results, MMPI was not a proper tool that could provide the factors influencing the outcome of CBT. In the future study, the authors need to use a different tool that can find the personality characteristics more directly.