• 국제물리치료학회지
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• 제4권2호
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• pp.566-572
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• 2013

This study aims to compared effect of balance between general walking exercise and power walking exercise. Twenty subjects were classified into two groups, general walking exercise(n=10) and power walking exercise(n=10). As a result, two group showed difference within the group and there is significant difference between two groups. 1) In compared static balance of sway area at pre-post test to exercise group, general walking exercise group did not change significantly. however, power walking exercise group did change significantly. and At sway distance, two group showed significant changes. 2) In compared Static balance between the groups sway area and sway path at pre-post test, two group showed significant changes. 3) In compared dynamic balance of center distance at pre-post test to exercise group, general walking exercise group was no significant difference in all directions. power walking exercise group was significant difference in all directions. 4) In compared dynamic balance between the groups sway area and sway path at pre-post test, there was no significant difference in leftward, rightward, forward directions and was significant difference in backward, overall direction. Therefore, power walking exercise can be recommended promote balance.

• ETRI Journal
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• 제39권2호
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• pp.151-162
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• 2017

With the remarkable growth in rich media in recent years, people are increasingly exposed to visual information from the environment. Visual information continues to play a vital role in rich media because people's real interests lie in dynamic information. This paper proposes a novel discrete dynamic swarm optimization (DDSO) algorithm for video object tracking using invariant features. The proposed approach is designed to track objects more robustly than other traditional algorithms in terms of illumination changes, background noise, and occlusions. DDSO is integrated with a matching procedure to eliminate inappropriate feature points geographically. The proposed novel fitness function can aid in excluding the influence of some noisy mismatched feature points. The test results showed that our approach can overcome changes in illumination, background noise, and occlusions more effectively than other traditional methods, including color-tracking and invariant feature-tracking methods.

• 대한기계학회논문집A
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• 제34권7호
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• pp.873-879
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• 2010

일반적으로 설계파라미터 변경에 의한 구조물의 동특성변화를 예측하는 연구에 비해 동특성 변화로부터 변경된 설계파라미터를 예측하는 연구는 잘 알려져 있지 않다. 여기에서는 감도계수와 반복법을 사용하여 비례감쇠계의 변경된 설계파라미터를 예측하였다. 감도계수는 변경에 의한 고유벡터의 변화로부터 구하였다. 이 방법을 3 층 전단 구조물에 적용하여 변경된 설계 파라미터를 예측하였으며 재 해석한 결과와 잘 일치함을 알았다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.478-485
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• 2003

Today, although there have been high technical developments of a compressor in the respect of its capacity, it has been so hard to develop in the respect of vibration and noise because mechanical structure of it has originally numerous vibration and noise. However, if we can grasp the point of systematic phenomena of vibration and noise through the understanding of dynamic characteristics in mechanical equipment, it may be possible to consider countermeasures. In this study about a reciprocal compressor, the part of its machinery is modeled as rigid body, and the part of its spring is modeled as flexible body, and then they are analyzed by DADS. Each rigid body and spring are connected with joint torque of a motor is applied to shaft, and pressure is applied to a piston so that a compressor can be revolved. Based on this modeling, influence of a compressor's vibration is analyzed through changes of offset, connecting rod and crank radius In the case of weight balance, it I produced after re-design, and then changes of vibration of a compressor's inside are checked through experiments. These analysis data may help set measures of reducing vibration of a reciprocal compressor.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.684-694
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• 2004

Presented in this dissertation is a new method of identifying the critical speed of rotor-bearing systems without actually reaching at the critical speed itself. Using the method, it is possible to calculate the critical speed by measuring a series of rotor responses at much lower rotating speeds away from and without reaching at the critical speed of the system. In the course of the procedures illustrated, not only the critical speed but also the damping ratio and the eccentricity of the system can be identified at the same time. Test rotor was tested on the Rotor Dynamics Test Facility at the Korea Institute of Machinery ＆ Materials. Korea, and the theory has been confirmed experimentally. The method can be adopted to monitor changes of the dynamic characteristics of critical rotating machinery before and after overhauls, repairs, exchanges of various parts, or to detect trends or direction of subtle changes in the dynamic characteristic parameters over a long periods of time.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.23-34
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• 2020

The paper revisits the author's previous paper to examine short-run and long-run dynamic relationships between macroeconomic variables and stock prices in Korea. The data is updated to the period for which monthly data are available from January 1986 to June 2018 (390 observations) retrieved from the Bank of Korea. The results of Johansen cointegration test indicate that at least one cointegrating equation exists, confirming there is a long-run equilibrium relationship between macroeconomic variables and stock prices in Korea. The results of vector error correction estimates confirm that: 1) the coefficient of the error correction term is significant with a negative sign, which is, a long-run dynamic relationship is observed between macroeconomic variables and stock prices; 2) for short-run dynamics, the nominal exchange rate of the Korean won per the US dollar is positively related to stock prices, while interest rates are negatively related to stock prices in the short-run; 3) the coefficient of global financial crises is insignificant, that is, the changes of stock prices are determined largely by their own dynamics in the model. The results suggest only that the global financial crises neither cause instability in the cointegrating vector, nor affect significant changes in the endogenous variables in the model.

• Journal of Power Electronics
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• 제19권1호
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• pp.254-264
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• 2019

This paper proposes an indirect current control technique based on a proportional resonant (PR) approach for the seamless mode transfer of utility interactive inverters. Direct-current and voltage hybrid control methods have been used for inverter control under grid-connected and islanded modes. A large bandwidth can be selected due to the structure of single-loop control. However, this results in poor dynamic transients due to sudden changes of the controller during mode changes. Therefore, inverter control based on indirect current is proposed to improve the dynamic transients by consistently controlling the output voltage under all of the operation modes. A PR-based indirect current control topology is used in this study to maintain the load voltage quality under all of the modes. The design processes of the PR-based triple loop are analyzed in detail while considering the system stability and dynamic transients. The mode transfer techniques are described in detail for both sudden unintentional islanding and islanded mode voltage quality improvements. In addition, they are described using the proposed indirect control structure. The proposed method is verified by the PSiM simulations and laboratory-scale VDER-HILS experiments.

• 대한물리의학회지
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• 제16권3호
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• pp.55-64
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• 2021

PURPOSE: The purpose of this study was to apply dynamic neuromuscular stabilization (DNS) to subjects with forward head posture (FHP) and to compare its effects on respiratory function as against the conventional neck stabilization exercise and neck stretching and extensor strengthening exercises. METHODS: The whole-body posture measurement system was used to measure the degree of FHP, and a spirometer and a respiratory gas analyzer were used to measure the respiratory function. After the intervention was completed, the changes over time were analyzed in the DNS group, the neck stabilization exercise group, and the neck stretching and extensor strengthening exercise group. The inter-group difference in the changes was also analyzed. A repeated ANOVA was performed to compare the respiratory function according to the period between the three groups, and the least significant difference (LSD) method was used for the post hoc test. RESULTS: After the 6-week exercise period, respiratory functions, such as forced vital capacity (FVC), forced expiratory volume for 1 second (FEV1), forced expiratory volume for 1 sec/forced vital capacity (FEV1/FVC), maximum oxygen intake (VO₂max), and the volume of expired gas (VE), significantly improved according to the period (p < .05), but no inter-group differences were found. CONCLUSION: DNS is an effective training method, and can be applied along with neck stabilization exercise and neck stretching and extensor strengthening exercises, which are widely used in clinical practice, to people with FHP who cannot directly perform neck exercises to improve their respiratory function.

• 한국농공학회논문집
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• 제64권2호
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• pp.71-83
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• 2022

In this study, an indicator and assessment system for evaluating the monthly hydrological cycle was prepared using simple factors such as the landuse status of the watershed and topographic characteristics to the dynamic water balance model (DWBM) based on the Budyko framework. The parameters a1 of DWBM are introduced as hydrologic cycle indicators. An indicator estimation regression model was developed using watershed characteristics data for the introduced indicator, and an assessment system was prepared through K-means cluster analysis. The hydrological cycle assessment system developed in this study can assess the hydrological cycle with simple data such as land use, CN, and watershed slope, so it can quickly assess changes in hydrological cycle factors in the past and present. Because of this advantage is expected that the developed assessment system can predict changes in the hydrological cycle and use an auxiliary tool for policymaking.

• Communications for Statistical Applications and Methods
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• 제30권4호
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• pp.369-388
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• 2023

In this paper, we develop the two-step procedure that detects and estimates the position of structural changes for multivariate nonstationary time series, either on mean parameters or second-order structures. We first investigate the presence of mean structural change by monitoring data through the aggregated cumulative sum (CUSUM) type statistic, a sequential procedure identifying the likely position of the change point on its trend. If no mean change point is detected, the proposed method proceeds to scan the second-order structural change by modeling the multivariate nonstationary time series with a multivariate locally stationary Wavelet process, allowing the time-localized auto-correlation and cross-dependence. Under this framework, the estimated dynamic spectral matrices derived from the local wavelet periodogram capture the time-evolving scale-specific auto- and cross-dependence features of data. We then monitor the change point from the lower-dimensional approximated space of the spectral matrices over time by applying the dynamic principal component analysis. Different from existing methods requiring prior information on the type of changes between mean and covariance structures as an input for the implementation, the proposed algorithm provides the output indicating the type of change and the estimated location of its occurrence. The performance of the proposed method is demonstrated in simulations and the analysis of two real finance datasets.