• Smart Media Journal
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• v.10 no.2
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• pp.100-109
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• 2021

As the COVID-19 vaccination begins, it is necessary to safely store and manage the vaccination history for vaccinated people, as well as provide only the minimal information for the requested purpose, not in the form of all or nothing, to the institution requesting vaccination personal information. This paper proposes a scheme to safely store and manage the people's vaccination records in a non-forgeable blockchain, and to ensure that users provide only the minimal information necessary to the verifier from their vaccination personal information. A user authorizes the verifier to access the information he has consented with by entering the fingerprint on his smartphone, and in this process, no personal information or secrets can be exposed to an attacker. In addition, it is guaranteed that it is neither possible to impersonate the user nor to steal user personal information even in the case of theft or loss of the smartphone, or leakage of information from the vaccination history management institution. Using the scheme, users have no fear on external exposure of personal information and follow-up damage due to excessive information provision by giving out only the minimal information suited to the verifier.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.2
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• pp.113-121
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• 2021

The occurrence mechanisms of heatwave have been conventionally studied at a synoptic scale. However, the implications of precedent droughts on the following up heatwave occurrences have not been elucidated and are important to address the complex causal mechanisms of heatwaves. Therefore, this study evaluated the causality and implication of the seasonally antecedent droughts to summer heatwaves that occurred for 46 years since 1974 using partial least squares-structural equation modeling (PLS-SEM). The resulting contribution of winter (spring and summer) droughts to summer heatwaves for Seoul-Gyeonggi, Gangwon, and Chungcheong provinces were 37 % (29 % and 22 %), 21 % (18 % and 29 %), and 17 % (8 % and 38 %), respectively. This is due to the regional variability of seasonal drought impacts. Furthermore, Gangwon and Chungcheong provinces, which have a higher level of impacts of summer droughts to summer heatwaves, are more likely to be exposed to the compound drought-heatwave damages compared to Seoul-Gyeonggi province, which has relatively a low-level impact of summer drought.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.114-121
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• 1994

Population densities of intermediate nymphs and egg saw of Matsucoccus thunbergianae, a major insect pest of Pinus thunbergiona in southern coastal area of Korean peninsula, were est~mated. Tree samples of ca. 10cm D.B.H. were collected from old infestation area and newly invaded area. The numben of plimaly branches per tree were not significantly different by the locality, but those of secondaly and smaller branches were smaller in old infestation area The numbers of intermediate nymphs per tree in old infestation area and in newly invaded area were 10.8 and 13.1 times more than those on the trunk, respectively Approximately between 4, 200 and 208, 500 nymphs per tree were estimated. Men secondaw and smaller bmnch samples collected from the basal part of middle crown height, or from the central or the basal part of lower crown height, the number of samples required for the emr range of 20% were 21 and 11 far 10-20cm and 20-3 crn long branches, respectively. Approx~mately 63.6% of egg sacs of the whole tree were on the trunk. The node/intemode bearing the largest branch had the highest egg sac density; including that, four adjacent nodes/intemodes had ca. 37% of egg saw on the trunk.

• Journal of Broadcast Engineering
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• v.18 no.3
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• pp.445-454
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• 2013

By using the radio propagation prediction of Rec. ITU-R P.1546, geographic information system, and S-I plane, we presented the methodology of interference analysis based on the minimum coupling loss, and also suggested the local coordinate system for calculating azimuth and elevation angles between the victim receiver and the interferer for an arbitrary antenna pattern. To check the presented algorithm, the map with the land-sea mixed area was taken for the given area of $80{\times}60[km^2]$ as real geography information. Field strength, path profile, and protection ratio with maximum allowable interference level have been illustrated for radar and fixed wireless system for the assumed frequency. In addition interference power of the victim receiver was calculated asa function of azimuth and elevation angles of the interferer. The developed methodology of interference analysis in the VHF and UHF bands can be actually applied to assess interoperability as well as compatibility in the civil or military applications.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.49-55
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• 2009

Typhoons are usually influencing at least 3 or 4 times per year in Korean peninsula and they accompanied with strong winds and heavy rains and then brought tremendous loss of properties and lives. Especially typhoon "MAEMI" resulted in a lot of marine accidents of vessels such as sinking, stranding, collision etc. at anchoring or on berthing in pier. If the typhoon comes up to expected area influencing the incidents, the vessel tries to escape from the route of typhoon or anchor in sheltering anchorage. However, consideration of the anchoring or judgement of ship's safety against strong winds is decided only by the experience of operators without detail evaluation of the safety. Therefore, this paper evaluated the safety of T.S. HANBADA by comparing the external forces with the holding powers. Furthermore, based on this evaluation, the anchoring manual was produced for the maximum endurable wind velocity, the general precautions and the actions taken on the ship with steps.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.131-139
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• 1992

Based on the equi-flooding line theory, this study suggests method of evaluating safety of detent tion reservoirs with drainage pumping facilities in Seoul metropolitan area, and derives equi-flooding lines according to destruction frequency for each detention reservoir. In most part of detention reservoirs, its flood prevention are so much dependent upon drainage capacity that inland flooding prevention can be serious problems in case of its malfunction. In this study, the detention reservoirs which are below 5 year destruction frequency estimated as 29.3%, and below 10 year as 39.6% of the total. To improve reservoir safety, the detention reservoir capacities (including drainage and pumping capacity) should be upgraded above 20 year in its destruction frequency, and its reinforcement capacities are calculated.

• Fire Science and Engineering
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• v.29 no.6
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• pp.71-75
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• 2015

Recently, Since buildings are bigger and higher, the damage of human life can be increased by fire flame and smoke in fire. Smoke control system is necessary to decrease this damage. Therefore, Air supply pressurization smoke control system is applied to vestibule of escape stairway. NFSC requires pressure differential of 40 Pa~60 Pa, but pressure differential is over 60 Pa in the field. It is known that the cause of this over pressure differential is much leakage of damper. Over pressure differential can bad effect to escaper by pressurizing the door. Analyze the real leakage of damper by testing for identifying this problems. The result of testing, leakage is $0.090m^3/s{\sim}0.154m^3/s$. It is necessary to limit the leakage of dampers for safe of escapers.

• Fire Science and Engineering
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• v.24 no.4
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• pp.86-91
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• 2010

In event of a tunnel fire, all kinds of equipment can be destroyed in high temperature that can exceed $1300^{\circ}C$, fatal structural demage can be caused by spalling of concrete structural elements. To make matters worse, there is a high possibility of the secondary damage which can lead to the collapse of the shear resisting structure. Accordingly, it is time that we developed the technology to counter fires in connection with the fire-resistant design of a tunnel structure. To secure the reliability of the fire-resistance performance of a tunnel structure, it is necessary to assess the fire's behavior on every structural element exposed to the fire as well as to calculate the tunnel fire intensity and the quantity of heat released. In this study, we drew out the fire damage range of each structural element of a tunnel and the minimum thickness of concrete cover for each fire-resistant material through some actual experiments of fire behavior on the structural elements of a tunnel.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.429-429
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• 2021

2019년 발생한 인천광역시 붉은 수돗물 사태로 급수구역에 포함된 26만 1천 세대, 63만 5천 명이 직·간접적인 피해를 입은 바 있다. 경제적 피해액으로 추정할 경우 최소 1,280억 원 이상으로 보고된 바 있으며, 이와 같은 상수관망의 수질사고 확산은 장기간 동안 시민의 건강과 생활환경 수준을 저하시킨다. 따라서 상수도시스템의 수질사고확산 모델링 및 방지기술을 통한 수질안전성의 재확인이 필요하며, 이것은 상수도시스템의 지속가능성을 높여 국민이 체감하는 물 환경 수준 제고에 기여가 가능하다. 관망 내 수질해석을 직접적으로 수행하는 모델은 국외적으로 다양하게 개발(PODDS, EPANET-MSX, EPANET2.2 등)된 바 있으나 검·보정을 위한 수질측정 자료 부족 등으로 적용이 제한적이라는 한계가 현재에도 존재한다. 이를 보완하기 위해 수질자료에 비해 그 양이 많고 획득방법이 상대적으로 수월한 수리학적 계측자료 및 해석결과를 활용한 관로 내 체류시간 등을 활용한 연구가 수행된 바 있다. 그러나 이와 같은 수리학적 해석 결과를 활용하는 경우에도 계측자료를 기반으로 한 수리학적 검·보정은 필수적이라 할 수 있다. 본 연구에서는 관로 내 체류시간에 직접적인 영향을 미치는 유량 및 유속자료를 중심으로 수리학적 관망해석의 결과를 최적 검·보정하는 방법론을 제안하였다. 기존 상수관망 수리해석의 검·보정은 일부 지점에서 수압을 측정하고, 수리해석 결과로 도출되는 해당 지점의 수압이 실측된 결과와 유사하도록 관로의 유속계수를 적절히 보정하는 형태로 진행되었다. 그러나 본 연구에서는 관로유량과 유속자료의 목적함수 내 가중치를 수압자료보다 크게 설정하여 체류시간 중심의 검·보정이 수행될 수 있도록 하였으며, 검·보정 대상인자 역시 대수용가의 수요량, 수요패턴, 그리고 관로유속계수로 확장된 모형을 구축하였다. 최적화 기법으로는 메타휴리스틱 기법중 하나인 화음탐색법을 활용하였다. EPANET 2.2 Toolkit과 Visual Basic .Net을 연계하여 프로그래밍하였으며, 개발된 모형을 실제 지방상수도 시스템에 적용하여 분석하였다.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.790-803
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• 2019

The dioctyl terephthalic acid (DOTP) process produces plastic plasticizers by esterification of terephthalic acid with powder in the form of octanol. In this study, the dust explosion characteristics of terephthalic acid directly injected into the manhole in the form of powder in the presence of flammable solvent or vapor in the reactor of this process were investigated. Dust particle size and particle size distribution dust characteristics were investigated, and pyrolysis characteristics of dust were investigated to estimate fire and explosion characteristics and ignition temperature. Also, the minimum ignition energy experiment was performed to evaluate the explosion sensitivity. As a result, the average particle size of terephthalic acid powder was $143.433{\mu}m$. From the thermal analysis carried out under these particle size and particle size distribution conditions, the ignition temperature of the dust was about $253^{\circ}C$. The lower explosive limit (LEL) of the terephthalic acid was determined to be $50g/m^3$. The minimum ignition energy (MIE) for explosion sensitivity is (10 < MIE < 300) mJ, and the estimated minimum ignition energy (Es) based on the ignition probability is 210 mJ. The maximum explosion pressure ($P_{max}$) and the maximum explosion pressure rise rate $({\frac{dP}{dt}})_{max}$ of terephthalic acid dust were 7.1 bar and 511 bar/s, respectively. The dust explosion index (Kst) was 139 mbar/s, corresponding to the dust explosion grade St 1.