• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.582-585
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• 2004

Most of hard disk drives currently employ fluid dynamic bearing (FDB) for their rotor support. Stiffness of the FDB is affected by many design factors such as bearing clearance, fluid viscosity, and rotational speed. For the high rotating speed HDDs stiffness of the rotor is normally high enough to accomodate load disturbances. However small form factor HDDs that are to be operated in low power consumption are often designed with low stiffness rotors. Although the low stiffness rotor clearly benefits low power operation, it could damage the entire motor structure or head disk interface even by a light mechanical load disturbance such as shock or vibration. In addition, since a single channel HDD does not provide gram load equilibrium in axial direction the rotor could be tilted and make a hard contact to stator. A non-symmetric groove pattern could successfully compensate the tilted rotor angle during operation.

• Smart Structures and Systems
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• v.15 no.1
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• pp.41-55
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• 2015

This study proposes a laser based impedance measurement system and impedance based pipe corrosion and bolt-loosening monitoring techniques under temperature variations. For impedance measurement, the laser based impedance measurement system is optimized and adopted in this paper. First, a modulated laser beam is radiated to a photodiode, converting the laser beam into an electric signal. Then, the electric signal is applied to a MFC transducer attached on a target structure for ultrasonic excitation. The corresponding impedance signals are measured, re-converted into a laser beam, and radiated back to the other photodiode located in a data interrogator. The transmitted impedance signals are treated with an outlier analysis using generalized extreme value (GEV) statistics to reliably signal off structural damage. Validation of the proposed technique is carried out to detect corrosion and bolt-loosening in lab-scale carbon steel elbow pipes under varying temperatures. It has been demonstrated that the proposed technique has a potential to be used for structural health monitoring (SHM) of pipe structures.

• Journal of Oriental Neuropsychiatry
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• v.32 no.1
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• pp.39-53
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• 2021

Objectives: To analyze the reports of qualitative research about natural disasters in Korea. Methods: Nine published qualitative research studies were selected for the analysis. The selected reports were analyzed by Consolidated Criteria for Reporting Qualitative Research (COREQ), a reporting guideline for qualitative research. In addition, each subject of the study was qualitatively synthesized. Results: In the quality assessment using COREQ, detailed information about the researchers were insufficient. The results of the studies were integrated into six themes: "Disaster experience", "Disaster damage", "Dealing with disasters", "Disaster compensation issues", "Arbitration Resources", and "Post-disaster change". Conclusions: In further qualitative research on natural disasters, it is necessary to report the research according to the COREQ checklist. Based on the results of this study, continuous attention and research are needed to explore the areas of Korean medicine care in the event of a disaster.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2229-2236
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• 2021

In nuclear-related facilities, such as nuclear power plants, research reactors, accelerators, and nuclear waste storage sites, radiation detection, and mapping are required to prevent radiation overexposure. Sensor network systems consisting of radiation sensor interfaces and wxireless communication units have become promising tools that can be used for data collection of radiation detection that can in turn be used to draw a radiation map. During data collection, malfunctions in some of the sensors can occasionally occur due to radiation effects, physical damage, network defects, sensor loss, or other reasons. This paper proposes a reproduction strategy for radiation maps using a U-net model to compensate for the loss of radiation detection data. To perform machine learning and verification, 1,561 simulations and 417 measured data of a sensor network were performed. The reproduction results show an accuracy of over 90%. The proposed strategy can offer an effective method that can be used to resolve the data loss problem for conventional sensor network systems and will specifically contribute to making initial responses with preserved data and without the high cost of radiation leak accidents at nuclear facilities.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.209-214
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• 2023

The effect of thermal annealing on defect recovery of in-core neutron-irradiated 4H-SiC was investigated. Au/SiC Schottky diodes were manufactured using a 4H-SiC epitaxial wafer that was neutron-irradiated at the HANARO research reactor. The electrical characteristics of their epitaxial layers were analyzed under various conditions, including different neutron fluences (1.3 × 10¹⁷ and 2.7 × 10¹⁷ neutrons/cm²) and annealing times (up to 2 h at 1700 ℃). Capacity-voltage measurements showed high carrier compensation in the neutron-irradiated samples and a recovery tendency that increased with annealing time. The carrier density could be recovered up to 77% of the bare sample. Deep-level-transient spectroscopy revealed intrinsic defects of 4H-SiC with energy levels 0.47 and 0.68 eV below the conduction-band edge, which were significantly increased by in-core neutron irradiation. A previously unknown defect with a high electron-capture cross-section was discovered at 0.36 eV below the conduction-band edge. All defect concentrations decreased with 1700 ℃ annealing; the decrease was faster when the defect level was shallow.

• Journal of Environmental Health Sciences
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• v.48 no.1
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• pp.19-27
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• 2022

The industrial development and socioeconomic structures of a society are inextricably linked to occupational accidents and diseases. Since the 1970s, a series of major occupational diseases have occurred in South Korea, such as mercury poisoning in Munsong-myeon, carbon disulfide poisoning at Wonjin Rayon, and leukemia at Samsung Electronics. These incidents have caused us to take a critical look at the level of worker safety and health management within companies and the government. These serve as symbolic and representational events. Doctors, lawyers, and labor activists concerned about employee safety and lives came together for years to struggle with the government and industry in order to determine what caused the diseases and to obtain compensation for victims. They finally achieved recognition for occupational diseases and recompense for losses. It is difficult to find similar cases to the baby powder asbestos talc cases and the radon bed case internationally, or there is no case where such a large number of consumers have been potentially harmed. It is also difficult to prove that the damage took place due to the victims' diverse geographic locations and ages, as well as the disease's long incubation period. Based on this premise, businesses and the government have been apathetic in acknowledging these diseases and compensating for damages, with few practical outcomes. Furthermore, unlike the large-scale occupational disease cases, only a few people including expert groups were organized and actively participated in the settlement of these issues, so it remains unfinished business for our society to address.

• Journal of Wellbeing Management and Applied Psychology
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• v.5 no.4
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• pp.57-67
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• 2022

Purpose: The purpose of this study is to identify what research ethics issues are related to chemical incidents at the level of national disasters in Korea, and then to secure clear research ethics to prevent similar incidents from recurring. Research design, data and methodology: The study design was a case study of the humidifier disinfectant disaster in Korea. The humidifier disinfectant incident is a worldwide issue that has never occurred in the world. The main cause of the humidifier disinfectant incident that occurred only in Korea was the toxicity of the humidifier disinfectant contained in the humidifier spray. In this regard, research ethics will be derived through related laws and systems, research ethics status, incident damage and compensation, prosecution's investigation status, and the final precedent of the Supreme Court. Results: Although the lack of laws and systems of government departments related to humidifiers is important in the research results, the violation of ethics regulations by researchers during research experiments has become a decisive problem. Conclusions: In conclusion, the most important thing is that the research bioethics of researchers at the forefront should take precedence over any other values, especially during experiments and research related to public health.

• Smart Structures and Systems
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• v.33 no.1
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• pp.41-53
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• 2024

Grouting sleeves are an essential connecting component of prefabricated components, and the quality of grouting has a significant influence on structural integrity and seismic performance. The embedded grouting sleeve (EGS)'s grouting defects are highly undetectable and random, and no effective monitoring method exists. This paper proposes an ultrasonic guided wave method and provides a set of guidelines for selecting the optimal frequency and suitable period for the EGS. The optimal frequency was determined by considering the group velocity, wave structure, and wave attenuation of the selected mode. Guided waves are prone to multi-modality, modal conversion, energy leakage, and dispersion in the EGS, which is a multi-layer structure. Therefore, a time-reversal (TR)-based multi-mode focusing and dispersion automatic compensation technology is introduced to eliminate the multi-mode phase difference in the EGS. First, the influence of defects on guided waves is analyzed according to the TR coefficient. Second, two major types of damage indicators, namely, the time domain and the wavelet packet energy, are constructed according to the influence method. The constructed wavelet packet energy indicator is more sensitive to the changes of defecting than the conventional time-domain similarity indicator. Both numerical and experimental results show that the proposed method is feasible and beneficial for the detection and quantitative estimation of the grouting defects of the EGS.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.2
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• pp.37-81
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• 2015

AirAsia QZ8501 Jet departed from Juanda International Airport in, Surabaya, Indonesia at 05:35 on Dec. 28, 2014 and was scheduled to arrive at Changi International Airport in Singapore at 08:30 the same day. The aircraft, an Airbus A320-200 crashed into the Java Sea on Dec. 28, 2014 carrying 162 passengers and crew off the coast of Indonesia's second largest city Surabaya on its way to Singapore. Indonesia's AirAsia jet carrying 162 people lost contact with ground control on Dec. 28, 2014. The aircraft's debris was found about 66 miles from the plane's last detected position. The 155 passengers and seven crew members aboard Flight QZ 8501, which vanished from radar 42 minutes after having departed Indonesia's second largest city of Surabaya bound for Singapore early Dec. 28, 2014. AirAsia QZ8501 had on board 137 adult passengers, 17 children and one infant, along with two pilots and five crew members in the aircraft, a majority of them Indonesian nationals. On board Flight QZ8501 were 155 Indonesian, three South Koreans, and one person each from Singapore, Malaysia and the UK. The Malaysia Airlines Flight 370 departed from Kuala Lumpur International Airport on March 8, 2014 at 00:41 local time and was scheduled to land at Beijing's Capital International Airport at 06:30 local time. Malaysia Airlines also marketed as China Southern Airlines Flight 748 (CZ748) through a code-share agreement, was a scheduled international passenger flight that disappeared on 8 March 2014 en route from Kuala Lumpur International Airport to Beijing's Capital International Airport (a distance of 2,743 miles: 4,414 km). The aircraft, a Boeing 777-200ER, last made contact with air traffic control less than an hour after takeoff. Operated by Malaysia Airlines (MAS), the aircraft carried 12 crew members and 227 passengers from 15 nations. There were 227 passengers, including 153 Chinese and 38 Malaysians, according to records. Nearly two-thirds of the passengers on Flight 370 were from China. On April 5, 2014 what could be the wreckage of the ill-fated Malaysia Airlines was found. What appeared to be the remnants of flight MH370 have been spotted drifting in a remote section of the Indian Ocean. Compensation for loss of life is vastly different between US. passengers and non-U.S. passengers. "If the claim is brought in the US. court, it's of significantly more value than if it's brought into any other court." Some victims and survivors of the Indonesian and Malaysia airline's air crash case would like to sue the lawsuit to the United States court in order to receive a larger compensation package for damage caused by an accident that occurred in the sea of Java sea and the Indian ocean and rather than taking it to the Indonesian or Malaysian court. Though each victim and survivor of the Indonesian and Malaysia airline's air crash case will receive an unconditional 113,100 Unit of Account (SDR) as an amount of compensation for damage from Indonesia's AirAsia and Malaysia Airlines in accordance with Article 21, 1 (absolute, strict, no-fault liability system) of the 1999 Montreal Convention. But if Indonesia AirAsia airlines and Malaysia Airlines cannot prove as to the following two points without fault based on Article 21, 2 (presumed faulty system) of the 1999 Montreal Convention, AirAsia of Indonesiaand Malaysia Airlines will be burdened the unlimited liability to the each victim and survivor of the Indonesian and Malaysia airline's air crash case such as (1) such damage was not due to the negligence or other wrongful act or omission of the air carrier or its servants or agents, or (2) such damage was solely due to the negligence or other wrongful act or omission of a third party. In this researcher's view for the aforementioned reasons, and under the laws of China, Indonesia, Malaysia and Korea the Chinese, Indonesian, Malaysia and Korean, some victims and survivors of the crash of the two flights are entitled to receive possibly from more than 113,100 SDR to 5 million US$ from the two airlines or from the Aviation Insurance Company based on decision of the American court. It could also be argued that it is reasonable and necessary to revise the clause referring to bodily injury to a clause mentioning personal injury based on Article 17 of the 1999 Montreal Convention so as to be included the mental injury and condolence in the near future.

• Journal of Legislation Research
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• no.44
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• pp.571-610
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• 2013

The current patent system is more often used for defensive purposes to exclude others' use or as a means to hold unfair strong positions in negotiations rather than for the original purpose as the dissemination and active use of useful technology. An injunction together with a damage is an important remedy for patent infringements. However, unlike a claim for damages, injunctions do not require the subjective requirement of intent and negligence or the occurrence of loss. If the validity of the patent and the fact of infringement are confirmed, automatically injunctions are issued without consideration of other circumstances. So a patent holder would exclude others' use and have a powerful position in negotiations because of injunctions for patent infringements. Therefore, those injunctions for patent infringements should be flexibly restricted according to cases under the premise to ensure fair compensation for the patent owner, rather than absolutely admitting injunctions for patent infringements like now. If then, it would serve the use of a useful technology and industrial development as the purpose of the patent system. First of all, judgments for preliminary injunctions should be strict and by deliberate decision on the merits permanent injunctions should be determined. In addition, it is needed that court's discretion possible to considerate 'the need for an injunction'. When the courts judge 'the need for an injunction', 'whether a patent holder has implemented a patent invention, the possibility of monetary compensation and the ability of the infringer for damages, a patent holder's intent to license and whether an injunction has been used as a weapon of negotiation, the proportion of patent technology in the entire products, the characteristics of patent technology and the possibility of patent invalidity, the competitive relationship for market share, the public interests and gains and losses between the parties and so on' should be considered. After these judgements, if 'the need for an injunction' is not approved, a patent owner would be protected by post-monetary compensation. However, because damages are related to illegal conducts in the past, in the case that an injunction is restrained, measures to ensure the legal implementation in the future are needed. It is primarily desirable that reasonable royalty is estimated throughout private negotiations between parties, but if agreement between the parties does not occur, patent owner should be able to claim the royalty for future.