• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.4
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• pp.36-42
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• 2018

Although continuous passenger injuries and physical damages are repeated due to the unexpected aviation turbulence encountered during operations, there is still exist the limitation for preventing recurrence of similar events because the lack of real-time information and delay in technological developments regarding various operating conditions and variable weather phenomena. The purpose of this study is to compare and analyze the meteorological data of the aviation turbulence occurred and actual flight data extracted from the Quick Access Recorder(QAR) to provide some precursors that the pilot can identify aviation turbulence early by referring thru the flight instrumentation indications. The case applied for this study was recent event, a scheduled flight from Incheon Airport, Korea to Narita Airport, Japan that suddenly encountered turbulence at an altitude of approximately 14,000 feet during approach. According to the Korea Meteorological Administration(KMA)'s Regional Data Assessment and Prediction System(RDAPS) data, it was observed that the strong amount of vorticity in the rear area of jet stream, which existed near Mount Fuji at that time. The QAR data analysis shows significant changes in the aircraft's parameters such as Pitch and Roll angle, Static Air Temperature(SAT), and wind speed and direction in tens of seconds to minutes before encounter the turbulence. If the accumulate reliability of the data in addition and verification of various parameters with continuous analysis of additional cases, it can be the precursors for the pilot's effective and pre-emptive action and conservative prevention measures against aviation turbulence to reduce subsequent passenger injuries in the aviation operations.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.42-54
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• 2021

The Aft-deck is being applied to the latest unmanned aircraft for the purpose of shielding the gas turbine exhaust plume or spreading jets to increase the mixing rate with the ambient air, thereby reducing the temperature of exhaust gases. In this study, we would like to find out how the performance of the nozzle is affected by the design variables of the Aft-deck. The design variables of aft-deck are selected as length, expansion angle and upper deck shape. The correlation between thrust and plume shielding rate with the length variable is presented. And the correlation between the thrust and the jet diffusion range is presented according to the expansion angle. In addition, the thrust increase effect is confirmed by the removal of the upper deck and the characteristics of transverse velocity vector determined mixing performance with external flow.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.453-456
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• 2023

Fighter jets employ guided missiles equipped with seekers to counter enemy air threats. Short range guided missiles(SRM) usually carry infrared(IR) seekers and are used to engage targets within visual range. On the other hand, medium range guided missiles(MRM) often utilize radio frequency(RF) seekers to engage targets beyond visual range. Medium range guided missiles do not activate their seekers until they reach the detection range of the seeker, and the aircraft's radar guides them for a certain distance. This guidance method is called Missile Data Link(MDL), and it can be implemented in either one-way or two-way communication modes, depending on the missile's communication system. In this paper, we discuss MDL based on these two communication modes, along with the integration of RADAR, mission computers, and guided missiles.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.169-179
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• 2023

Filtered containment system is a passive safety system that controls the over-pressurization of containment in case of a design-based accidents by venting high pressure gaseous mixture, consisting of air, steam and radioactive particulate and gases like iodine, via a scrubbing system. An indigenous lab scale facility was developed for research on iodine removal by venturi scrubber by simulating the accidental scenario. A mixture of 0.2 % sodium thiosulphate and 0.5 % sodium hydroxide, was used in scrubbing column. A modified mathematical model was presented for iodine removal in venturi scrubber. Improvement in model was made by addition of important parameters like jet penetration length, bubble rise velocity and gas holdup which were not considered previously. Experiments were performed by varying hydrodynamic parameters like liquid level height and gas flow rates to see their effect on removal efficiency of iodine. Gas holdup was also measured for various liquid level heights and gas flowrates. Removal efficiency increased with increase in liquid level height and gas flowrate up to an optimum point beyond that efficiency was decreased. Experimental results of removal efficiency were compared with the predicted results, and they were found to be in good agreement. Maximum removal efficiency of 99.8% was obtained.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.78-84
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• 2023

Recently, the world's countries are tightening regulations on CO2 and air pollutants emission to solve them. In addition, eco friendly vehicles is increasing to replace automobiles in internal combustion engine. The government is supporting the expansion of hydrogen refueling infrastructure according to the hydrogen economy road map. In particular, refueling station is important to secure the safety that supplies high-pressure hydrogen with a wide LFL range. This paper is on guidelines for the determination safety distances to ensure worker safety from accident as jet fire. The safety distance is set according to the procedure of the EIGA doc 075/21. For accident frequency is upper 3.5E-05 per annum, safety distance is decided via consequence analysis where the risk of harm is below individual harm exposure threshold.

• Safety and Health at Work
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• v.15 no.1
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• pp.87-95
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• 2024

Background: This study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. Objectives: The objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. Methods: A literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. Results: Maintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. Conclusion: Further research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

• Clinical and Experimental Pediatrics
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• v.46 no.12
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• pp.1235-1241
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• 2003

Purpose : We assessed the dynamic characteristics of 16 nebulizer/compressor combinations currently available in Korea. Methods : The 16 nebulizer/compressor combinations(Pariboy Type 38/Long life, Pariboy Type N/Long life, Pariboy Type N/Salter 8900, Pariboy Type N/LC, Devilbiss pulmoaid-LT/Hudson, Devilbiss pulmoaid/Hudson, Mesmed neb-300/Own, San-up 3040/Hudson, Midas(Basic)/Own, AirJolie 2/Hudson, Thomas 1127/Salter 8900, Noel NE-2000/Salter 8900, Omron CX3/Hudson, Chang Woo CWN-100/Salter 8900, Voyage/Mefar, Chang Woo ASI-Pro/Medel jet pulse) were evaluated in terms of particle size and mass output. In addition, we determined the effects of nebulizer fill volume on mass output. Results : Pariboy Type N/Long life has the highest respirable mass of 0.184 mg/min and Mesmed Neb-300/Own has the lowest 0.019 mg/min. Pariboy Type N/Long life has the highest mass output of 0.68 mg/min and the shortest mass median aerodynamic diameter(MMAD) of $3.76{\mu}m$. All combinations other than Pariboy Type N/Long life produced a MMAD of over $5{\mu}m$. MMAD over a 5 min nebulization ranged 3.76 to $9.83{\mu}m$. There were no significant effects of fill volume on mass output. Conclusion : We concluded that there is a wide variation in performance of nebulizer/compressor combinations. The characteristics of nebulizer/compressor combinations should be considered in selecting products.

• The Korean Journal of Air & Space Law and Policy
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• v.31 no.2
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• pp.3-35
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• 2016

The United States Constitution gives power to the federal district courts to hear admiralty cases. 28 U.S.C. §.133, which states that "The district courts shall have original jurisdiction, exclusive of the Courts of the States, of any civil case of admiralty or maritime jurisdiction." However, the determination of whether a case is about admiralty or maritime so that triggers admiralty jurisdiction was not a simple question. Through numerous legal precedents, the courts have drawn a line to clarify the boundary of admiralty cases. This unique jurisdiction is not determined by the mere involvement of a vessel in the case or even by the occurrence of an event on a waterway. As a general rule, a case is within admiralty jurisdiction if it arises from an accident on the navigable waters of the United States (locus test) and involves some aspect of maritime commerce (nexus test). With regarding to the maritime nexus requirement, the US Supreme Court case, Executive Jet Aviation, Inc. v. City of Cleveland, held that federal courts lacked admiralty jurisdiction over an aviation tort claim where a plane during a flight wholly within the US crashed in Lake Erie. Although maritime locus was present, the Court excluded admiralty jurisdiction because the incident was "only fortuitously and incidentally connected to navigable waters" and bore "no relationship to traditional maritime activity." However, this historical case left a milestone question: whether an aircraft disaster occurred on navigable water triggers the admiralty jurisdiction, only for the reason that it was for international transportation? This article is to explore the meaning of admiralty jurisdiction over aviation accidents at US courts. Given that the aircraft engaged in transportation of passenger and goods as the vessels did in the past, the aviation has been linked closely with the traditional maritime activities. From this view, this article reviews a decision delivered by the Seventh Circuit regarding the aviation accident occurred on July 6, 2013 at San Francisco International Airport.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.55-65
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• 2013

Sterilization of Neurospora crassa has been investigated in this research by using a surface air plasma with dielectric barrier discharged (DBD) structure under atmospheric pressure. The sinusoidal alternating current has been used in this experiment with discharge voltage of 1.4~2.3 kV. The phase difference between the voltage and current signals are found to be almost 80 degree due to the capacitive property of dielectric barrier. Temperature on the biomaterials has been minimized by radiating the heat with the air cooling system. It is noted that the substrate temperature remains under 37 degree for plasma exposure time of 10 minutes with operation of cooler system. It is found that the ozone, $O_3$, has been measured to be about 25~30 ppm within 1 cm region and to be about 5 ppm at the 150 cm downstream region away from the suface plasma. It is also noted that the nitric oxide, NO, and nitric dioxide, $NO_2$, are not nearly detected. Germination rate and mitochodrial activity of Neurospora crassa immersed in the deionized water have been found to be drastically decreased as the plasma treatment time and its electrical power are increased in this experiment. Here, the mitochondrial activity has been analyzed by MTT (3-(4,5-dimethy lthiazol-2yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. However, sterilization of Neurospora crassa immersed in the Vogel's minimal media has been found to be low by plasma treatment, which is caused by surrounding background solution. This research shows the sterilization possibility of Neurospora crassa by using the noncontated surface DBD plasma, which is different from the plasma jet. This is mainly attibuted to the reactive species generated by the surface plasma, since they play a major role for inhibition of micobes such as Neurospora crassa.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.557-574
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• 2020

The purpose of this study is to analyze the cause of high PM2.5 mass concentrations in Cheongju for the period of non-Asian dust days using the weather chart, the stream lines at 850 hPa, the backward trajectory, and the weather and air quality model. As a result of analyzing the time series of PM2.5 concentrations and weather charts for the episodic days in Cheongju, the weather patterns were shown in related to long-range transport of PM2.5 from China or surrounding areas. In fact, in the PM2.5 time series, 60-80 ㎍ m-3, which is more than 2-3 times higher than the concentration attributed to Cheongju activities, was observed as a background concentration related to long-range transport. The distribution of high PM2.5 concentration was typically dependent on the locations of the high and low pressures above the ground while the upper jet stream passed through the Korean Peninsula. Consequently, the high PM2.5 concentration in Cheongju is due to massive air pollutants in the form of smog originated from industrial, household and energy combustion sources of Beijing and other nearby regions of China. These air pollutants move along a fast zonal wind caused by the atmospheric pressure arrangement. high concentration of PM2.5 in Cheongju City is because the mass of air pollutants in the form of smog generated from industrial, household and energy combustion origins in Beijing or other nearby regions of China move along a fast wind speed zone according to the atmospheric pressure arrangement of long-distance transportation. Air pollutants including PM2.5 show an M-shaped pattern that passes through the topography of the Cheongju basin from north to south as a belt or band-shaped pollutant. The ground high pressure according to the above-ground high pressure expansion area and cut-off low or low pressure arrangement, or the bands in the form of river stems appear in a gradual incremental pattern that changes into a U-shape under the influence of the wind.