• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.46-51
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• 2001

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. In this system, a voice coil motor (VCM) is used as the primary stage while a milliactuator is used as the secondary stage. We have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce controller design method, PQ method. PQ method reduces the controller design problem for DISO(dual-input/single-output) systems to two standard controller design problems for SISO(single-input/single-output) problems. The first part of PQ method directly address the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Atmosphere
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• v.28 no.3
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• pp.337-355
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• 2018

Ultrafine particles (< 100 nm in diameter, UFP) are known to be more toxic per unit mass than larger particles and contribute to more than 90% in particle number concentrations in urbanized cities but much less in mass. The major sources of UFP are vehicle emissions in urban areas. Due to their tiny size (the sizes of UFP from vehicle emissions range from 10 to 60 nm depending on engine and fuel types), inhaled UFP can reach the deepest area of respiratory track (e.g., pulmonary alveoli) as well as all of the body via lymph and blood circulation causing various adverse health effects. This article reviews the sources and emission factors of UFP, temporal and spatial distributions in urban areas and their health effects reported by toxicological and epidemiological studies. We also compared the levels of UFP concentrations measured in other countries with those in Korean cities to evaluate the public exposure to UFP in Korea. Ultimately, we expect this study can contribute to developing the risk assessment techniques for public exposure to UFP in the urbanized cities in Korea.

• Journal of Arbitration Studies
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• v.22 no.1
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• pp.111-130
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• 2012

Judgment on the validity of patents on the subject of an arbitration does not. In other words, the occurrence of patents generated by the administrative action, and such administrative action by an authorized agency may be treated as legitimate until it is canceled. However, recent Supreme Court judgment on novelty and inventive step as well as judgments about the validity of the patent also made possible by the judiciary. This progress even in the mediation of an arbitral award which is premised on the validity of patents can be seen that possible. However, if the arbitration by an arbitrator if possible a certain portion of the limit exists. In other words, the effect of arbitration between the parties is valid. This patent is valid and invalid in arbitration even if the judgment relative to the effect ceases. In addition, the arbitration award and patent invalidation trial is in progress at the same time, if you consequently will reach a different conclusion. This can cause problems of double track. In addition, by extending the critical target recognition and enforcement in other countries can cause problems. Despite these problems, now about the validity of patents that it is possible intervention is necessary to discuss again.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.2
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• pp.9-13
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• 2019

The paper aims to investigate the performance of domestic Saudi Arabian ETFs. ETFs are investment vehicles in vogue. These instruments were the first levers for investors allowing them to enter some markets that have been highly protected or out of reach. Saudi Arabia, which has been promoted as an emerging country by MSCI, seeks to attract more foreign investors. The first ETFs were launched in the years 2010-2011. Even though their number has not increased since then, there is a desire to attract a large number of investors. We use premiums/discounts analysis, standard risk-return models, and tracking errors measurements to assess how closely their replicate the underlying benchmark based on monthly data. The results indicate that out of the three funds investigated two are slightly traded at premium, while the latter exhibit a price discount. However, tracking errors are at minimum for all funds suggesting that they track well the benchmark index. Further, the Jensen's model shows that alphas are negative or null, and betas capture largely the systematic risk which is consistent with index investing strategies. Finally, traditional risk-adjusted measures of performance are used to compare ETFs, and results exhibit negative ratios showing that portfolios achieve lower return than the risk-free rate.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.179-188
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• 2019

Laser beam is directional and small in divergence angle so that it is well qualified to deliver high intensity infrared energy into a coming MANPADS threat for aircraft survivability. The threat will be deceived and loose tracking of a target when it is exposed to the laser beam modulated relevant to the track mechanism of the threat. The laser beam goes through scattering inside the seeker of the threat and reach the detector in a stray light form, which is a critical phenomenon enabling jamming of the seeker. The mechanism of the laser beam based jamming against a pulse modulated infrared seeker is shown. Simulations are carried out to support the understanding of how the jam technique works.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.145-156
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• 2021

The research purpose of this paper is to empirically examine the effects of technological readiness and innovation on logistics performance. To build up and maintain an important role in global supply chains, nowadays it is obvious that countries and logistics providers need to achieve competitive advantage in terms of digitalization. However, there is a lack of empirical studies about the impacts of information technologies and innovation potential on the logistics efficiency of countries. Hence, the study analyzes whether the corresponding pillars of the Global Competitiveness Index (GCI) matter for the Logistics Performance Index (LPI) and its dimensions. For determining the effects, the pooled regression approach is applied. The results show that technological readiness and innovation are positively and statistically significantly correlated with logistics performance: competence and quality of logistics services, efficiency of customs clearance processes, ability to track and trace consignments, frequency with which shipments reach consignee within scheduled or expected time, and ease of arranging competitively priced shipments. The findings of this study suggest that investments in innovations and technology progress improve countries' logistics efficiency, which is an important prerequisite for enabling Logistics 4.0 and thus, Industry 4.0 and the digital transformation of the economy and society.

• Wind and Structures
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• v.37 no.4
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• pp.275-287
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• 2023

Subgrade differential settlement of high-speed railways was a pivotal issue that could increase the risk of trains operation. The risk will be further increased when trains in the subsidence zone are affected by crosswinds. In this paper, the computational fluid dynamics (CFD) model and finite element (FE) model were established, and the data transmission interface of the two models was established by fluid-solid interaction (FSI) method to form a systematic crosswind-train-track-subgrade dynamic model. The risk of high-speed train encountering crosswind in settlement area was analyzed. The results showed that the aerodynamic force of the trains increased significantly with the increase in crosswind speed. The aerodynamic force of the trains could reach 125.14 kN, significantly increasing the risk of derailment and overturning. Considering the influence of crosswind, the risk of train operation could be greatly increased. The safety indices and the wheel-rail force both increased with the increase of the wind speed. For the high-speed train running at 350 km/h, the warning value of wind speed was 10.2 m /s under the condition of subgrade settlement with wavelength of 20 m and amplitude of 15 mm.

• Asian Journal for Public Opinion Research
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• v.3 no.3
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• pp.145-155
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• 2016

Background: Asia is on track to become the region with the most elderly people in the world. The elderly population will reach 922.7 million by the middle of this century. Therefore, they will be cared for by the today's youth. Negative attitudes toward older people can make adolescents more uncomfortable relating to them. Objectives: The objective of this study was to evaluate validity and reliability of Kogan's attitude toward old people among nursing students in Thailand, Myanmar, and Indonesia. Methods: Content validation of the 34-item Kogan's attitude toward old people was examined by three geriatric nursing experts. The reliability was evaluated on 600 nursing students, from nursing colleges in Thailand (200), Myanmar (200), and Indonesia (200). Findings: The attitude scores towards the elderly ranged from 34 to 238. All of the 34 items were found to have significant item-to-total correlations (p< .05). The reliability results were as follows: In Thailand, Cronbach's alpha was .70 for the total scale, .72 for the positive scale, and .68 for the negative scale. In Myanmar, Cronbach's alpha was .68 for the total scale, .65 for the positive scale, and .66 for the negative scale. In Indonesia, Cronbach's alpha was .66 for the total scale, .71 for the positive scale, and .72 for the negative scale. Conclusions: These findings suggest that Kogan's attitude toward old people is reliable and valid for nursing students from Thailand, Myanmar, and Indonesia. However, Kogan's attitude toward old people should be revised by these countries, including changing wording on all items for better reliability. The revised version must then be tested for reliability and validity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.965-971
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• 2003

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. For this system. we have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce milliactuator and controller design method, PQ method. PQ method reduces the controller design problem for DISO (dual-input/single-output) systems to two standard controller design problems for SISO ( single-input/single-output) problems. The first part of PQ method directly addresses the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.257-270
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• 2017

Solar activity is known to be linked to changes in the Earth's weather and climate. Nonetheless, for other types of extreme weather, such as tropical cyclones (TCs), the available evidence is less conclusive. In this study the modulation of TC genesis over the western North Pacific by the solar activity is investigated, in comparison with a large-scale environmental parameter, i.e., El-$Ni{\tilde{n}}o$-Southern Oscillation (ENSO). For this purpose, we have obtained the best track data for TCs in the western North Pacific from 1977 to 2016, spanning from the solar cycle 21 to the solar cycle 24. We have confirmed that in the El-$Ni{\tilde{n}}o$ periods TCs tend to form in the southeast, reach its maximum strength in the southeast, and end its life as TSs in the northeast, compared with the La-$Ni{\tilde{n}}o$ periods. TCs occurring in the El-$Ni{\tilde{n}}o$ periods are found to last longer compared with the La-$Ni{\tilde{n}}o$ periods. Furthermore, TCs occurring in the El-$Ni{\tilde{n}}o$ periods have a lower central pressure at their maximum strength than those occurring in the La-$Ni{\tilde{n}}o$ periods. We have found that TCs occurring in the solar maximum periods resemble those in the El-$Ni{\tilde{n}}o$ periods in their properties. We have also found that TCs occurring in the solar descending periods somehow resemble those in the El-$Ni{\tilde{n}}o$ periods in their properties. To make sure that it is not due to the ENSO effect, we have excluded TCs both in the El-$Ni{\tilde{n}}o$ periods and in the La-$Ni{\tilde{n}}o$ periods from the data set and repeated the analysis. In addition to this test, we have also reiterated our analysis twice with TCs whose maximum sustained winds speed exceeds 17 m/s, instead of 33 m/s, as well as TCs designated as a typhoon, which ends up with the same conclusions.