• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.103-110
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• 1995

Dynamic wedge system has been introduced to modify the beam profile and to make homogeneous isodose curves in the mass of irregular shape. Before the clinical use of dynamic wedge, several factors such as wedge transmission factor, dose profile, percent depth dose, and wedge angle have to be measured quantitatively. Film dosimetry is used to evaluate these factors in this study. A comparison of the result of the dynamic wedge to physical wedge system is made. A positive result for the application of the dynamic wedge to clinic is derived even though there is a limitation in accuracy of the dosimetry system used. To measure all factors quantitatively, more accurate dosimetry systems are required.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.43-53
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• 2021

Dynamic behavior of piezoelectric ZnO nanowires is investigated using finite element analyses (FEA) on FE models constructed based on previous experimental observations in which nanowires having aspect ratios of 1:2. 1:31, and 1:57 are obtained during a hydrothermal process. Modal analyses predict that nanowires will vibrate in lateral bending, uniaxial elongation/contraction, and twisting (torsion), respectively, for the three ratios. The natural frequency for each vibration mode varies depending on the aspect ratio, while the frequencies are in a range of 7.233 MHz to 3.393 GHz. Subsequent transient response analysis predicts that the nanowires will behave quasi-statically within the load frequency range below 10 MHz, implying that the ZnO nanowires have application potentials as structural members of electromechanical systems including nano piezoelectric generators and piezoelectric dynamic strain sensors. When an electric pulse signal is simulated, it is predicted that the nanowires will deform in accordance with the electric signal. Once the electric signal is removed, the nanowires exhibit a specific resonance-like vibration, with the frequency synchronized to the signal frequency. These predictions indicate that the nanowires have additional application potential as piezoelectric actuators and resonators.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1918-1924
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• 2000

Dynamic characteristics of a vertically coupled structure used for micro gyroscopes, is studied. The coupled motion between the reference and sensing vibrations causes the zero-point output which means non-zero sensing vibration without angular velocity. This structural coupling deteriorates sensing performance and dynamic stability. We theoretically analyze dynamic characteristics associated the coupling phenomenon. Effects of reference frequency and coupling factor on the rotational direction and amplitude of elliptic oscillation are studied. A method to predict the existence of curve veering or crossing in frequency trajectories is introduced for the application to the design of micro gyroscopes with a vertically decoupled structure.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.6
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• pp.253-258
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• 2000

This paper presents an application of Kohonen neural networks to assess the dynamic security of power systems. The dynamic security assessment(DSA) is an important factor in power system operation, but conventional techniques have not achieved the desired speed and accuracy. The critical clearing time(CCT) is an attribute which provides significant information about the quality of the post-fault system behaviour. The function of Kohonen networks is a mapping of the pre-fault system conditions into the neurons based on the CCTs. The power flow on each line is used as the input data, and an activated output neuron has information of the CCT of each contingency. The trajectory of the activated neurons during load changes can be used in on-line DSA efficiently. The applicability of the proposed method is demonstrated using a 9-bus example.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.81-87
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• 2000

This paper presents an application of forced oscillation technique to measure pitch dynamic stability derivatives of a missile model in the low speed wind tunnel. The missile model is oscillated by D.C. electric servomotor with constant amplitudes and frequencies. Phase shift is determined as the difference of peak values between input and output signals from the dynamic stability balance installed at the center of gravity of the model. Stability derivatives were calculated by using phase shifts, amplitudes, forcing moments and input frequencies. Test results show the proper usage of the force oscillation technique with good damping effects.

• Physical Therapy Rehabilitation Science
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• v.9 no.4
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• pp.281-286
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• 2020

Objective: This study examined the effects of dynamic tape applied to the patellofemoral joint on the knee valgus angle, muscle activity, and ground reaction force during a single leg squat (SLS) and single leg landing (SLL). Design: Cross-sectional study. Methods: Twenty-four subjects (11 male, 13 female) who met the inclusion criteria were screened by the knee palpation and patella compression tests. First, the knee valgus angle and muscle activity during SLS were measured. Second, the knee valgus angle and ground reaction force during SLL were measured. For the intervention, a patella joint loop using dynamic tape was used. The knee valgus angle, muscle activities in SLS and SLL after the intervention, and the ground reaction force were measured in the same way. A paired t-test was used to examine the difference between before and after the intervention. Results: The knee valgus angle showed a statistically significant improvement after dynamic taping application in SLS and SLL (p<0.05). The differences in muscle activity of the VL/VMO and ground reaction forces were not statistically significant after dynamic taping application in SLS and SLL. Conclusions: This study showed that dynamic taping applied around the patellofemoral joint was effective in improving the knee valgus angle in SLS and SLL and had a reduced risk of secondary injury during sports activity.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.77-84
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• 2019

Purpose : Elastic taping is a therapeutic method, used for treatment of various musculoskeletal and neuromuscular deficits. However, there is limited evidence, of the effects of ankle elastic taping in neurologic patients. The purpose of this study, was to investigate the effect of elastic taping on gait, in the affected ankle area of chronic stroke patients. Methods : Subjects were randomized to receive 30 chronic stroke patients, who were 6 months old from the date of onset according to screening criteria. Group I showed ankle joint taping, and Group II had ankle muscle taping. Dynamic balance and temporal and spatial gait, were measured before taping application, and after 30 minutes of taping application. Results : Dynamic balance was measured using the Time up & Go test (TUG). There was statistically significant difference, between Group I and Group II (p<.05). There was no statistically significant difference, between Group I and Group II. Temporal and spatial gait were measured using GaitRite. In Group I, there was significant difference, before and after taping (p<.05). In Group II, there was no significant difference, before and after taping (p>.05). There was significant difference in Group I, between Group I and Group II (p<.05). Conclusion : Results suggest that intervention using elastic taping, may have a positive effect, on rehabilitation diversity and function in stroke patients. Based on this, it can be used for rehabilitation of stroke patients. Various studies on the application method, and effect of the application site as well as application time, should be continued with stroke patients.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1361-1372
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• 2017

If an external attacker takes from a victim's smartphone a copy of a secret application or an application to which fingerprinting technique is applied, secret information can be leaked or the legitimate user can be misunderstood as an illegal redistributor, which results in a serious security problem. To solve this problem, this paper proposes an Android application code protection scheme using fingerprint authentication and dynamic loading. The proposed scheme divides one application into CLR(Class LoadeR) and SED(SEperated Dex). CLR is an APK file with the ability to dynamically load the SED, and the SED is a file containing the classes required to run the application. The SED is stored inside the smartphone after being encrypted, and the SED can be decrypted only if the user is successfully authenticated using his or her fingerprint. The proposed scheme can protect the application code from the attacker who physically acquired user's smartphone.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.357-362
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• 1996

• The Journal of Industrial Distribution & Business
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• v.6 no.4
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• pp.27-37
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• 2015

Purpose - This study first explores the possible dynamic relationship between ownership structure and firm performance using a panel of 4,900 Chinese-listed small- and medium-sized enterprises (SMEs) from 1999 to 2012. Research design, data, and methodology - We address this issue through a dynamic panel model using a method of moments (GMM) technique and dynamic simultaneous equations to alleviate the potential endogenous problem: unobserved heterogeneity, simultaneity, and dynamic endogeneity. Results - Under the framework of dynamic endogeneity, firm performance has a significantly positive influence on ownership, but not vice versa. Ownership and performance can be explained by their owned lagged values, respectively. Moreover, intertemporal endogeneity exists among ownership, investment, and performance through the application of system dynamic equations, which implies that the relationship among ownership structure, investment, and firm performance is dynamic by nature. Conclusions - This study also significantly contributes to a better understanding of dynamic corporate governance by providing further empirical evidence from the largest capital market in the Asian region.