• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.415-422
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• 2014

There has been a lot of discussion to revise military helicopter crashworthiness design criteria. In this paper, newly revised crashworthiness criteria is analyzed centering around the Crashworthiness Index which is the core content of revised criteria. The Crashworthiness Index(CI) was conceived as an adequate method to quantify the crashworthiness capabilities of a rotorcraft design. The index can rate how well a new or derivative design complies with design requirements. The CI rating is made up of seven assessment areas. While the Basic Airframe Crashworthiness(BAC) area tends to be an objective calculation, other areas of the CI tend to be more subjective. Therefore, in this paper, detail CI calculation process for the BAC area is analyzed to inspect the effectiveness of revised criteria.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.918-921
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• 2008

There are various accident at the Construction site like fall, electric shock, roll over, clash, fire, body cutting. By the way, falls are the most causes accidents. So, the best way of decreasing Construction accidents is decreasing falls. Already, there are many studies about falls accidents, but those studies were pointed out unrealistic because falls accidents are increasing. For that reason, this study look for more concrete device. In this study, grasp the cause of falls accident from 2007 to 2008. 06. 30. And then, stand on this factor I set my face to look for the causes of falls accident. This access means will drive to remove core causes, and then that means will decrease the falls accidents. Moreover that means will contribute decreasing the hole construction accidents.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.142-149
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• 2013

As we, human expand its everyday life boundary to the geosynchronous orbit, we have experienced frequent chance of the atmospheric re-entry and surface impact of space objects(satellite and space debris). Recently a satellite re-entry monitoring room in Korea has been operated to predict the time and the location of the re-entry of space objects. However, we do not have a domestic version of a numerical re-entry model for normal operation using TLE (Two line Element) information from the United States Strategic Command yet. The space information from the several space operation centers has been used to analyse the re-entry situations. In this paper, the re-entry time is calculated with TLE based on the several atmosphere models, the result is comprehensively analyzed, a new re-entry case model fitted from the result of the predicted satellite re-entry times by a new Rubber Sheet Shift Method used by the domestic satellite re-entry room is suggested.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.47-55
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• 2021

When an abnormal landing occurs, aircraft structures should be designed to guarantee occupants survivability without preventing egress. To find out fire root causes at crash, lots of fixed aircraft crash tests were conducted. Appropriate crash load factors were established with the comprehension of structural behavior based on dynamic analysis and investigation of human tolerance. Cargo restraint criteria were set up considering passengers safety and operational cost while analyzing past cargo aircraft accident data using a probabilistic approach. Reviewing results of past crash tests, current crash landing load factor was appreciated physically, medically, and economically.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.23-32
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• 2021

The high-level Space Situational Awareness (SSA) objective is to provide to the users dependable, accurate and timely information in order to support risk management on orbit and during re-entry and support safe and secure operation of space assets and related services. Therefore the risk assessment for the re-entry of space objects should be managed nationally. In this research, the Software for Re-Entry Prediction of space objects (SREP) was developed for national SSA system. In particular, the rate of change of the drag coefficient is estimated through a newly proposed Drag Scale Factor Estimation (DSFE), and is used for high-precision orbit propagator (HPOP) up to an altitude of 100 km to predict the re-entry time and position of the space object. The effectiveness of this re-entry prediction is shown through the re-entry time window and ground track of space objects falling in real events, Grace-1, Grace-2, Tiangong-1, and Chang Zheng-5B Rocket body. As a result, through analysis 12 hours before the final re-entry time, it is shown that the re-entry time window and crash time can be accurately predicted with an error of less than 20 minutes.

• Journal of Korean Society of Disaster and Security
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• v.5 no.1
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• pp.1-6
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• 2012

This study analyzed the direct costs of fall accidents, which have the highest accident rate, for domestic construction industry workers. Firstly, the average insurance payment per person due to fall accidents in the construction industry is around 19 million won (18,971,000 won). Given that the average number of workers suffering fall accidents over ten years is 5,863, the total cost of losses from fall accidents is about 1.1 trillion won (111,360,000,000 won). Secondly, a cost-based economic feasibility analysis was done to develop nonstructural preventive measures for fall accidents. Since there was no data expressing the costs and effects of preventive measures in terms of monetary value, the economic feasibility analysis was attempted with a focus on how much the newly introduced preventive measures can reduce the accident loss costs due to fall accidents. Thirdly, if the accident loss size is grasped and the preventive measures for the causes of fall accidents are developed and strictly implemented, the insurance fee that can reduce the accident loss costs can be determined. Further study is needed to estimate the benefit of the accident loss cost reduction seen from the cost-based approach method.

• Applied Biological Chemistry
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• v.6
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• pp.61-77
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• 1965

In this experiment, Akiochi was studied especially on plant growth on the degraded soils. Besides, such soils were carefully examined on its character and plant body was analysed to know the difference in various mineral contents. For this purpose, paddy cultivation was done with the variety Pal Dal at Suwon, Sosa and Pyungtak. Three plots were chosen at each location as the normal and 2 levels of akiochi, a-the stronger and b-the weaker. Harvests from these 9 plots were measured agronomically and also chemically analysised. As for soil, after an observation on vertical section of soil, samples from each layer were also studied both physically and chemically. The results are summarized as follows. 1. Outer changes in rice plant and changes in yield components. 1) Rice from Akiochi soil showed remarkably shortened culm length, head length, protrusoion length, blade length of boot leaf, and coleoptile length, compared with that from the normal paddy field. 2) There was a tendency for Akiochi rice to have more heads per plant. 3) Akiochi rice showed poorer intercalary growth of upper 3 internodes. The ratio of this upper internode length to total culm length was also smaller in this case. Consquently the ratio of lower internode length to total culm length became larger than that from normal peddy field. 4) Akiochi rice showed significantly fewer first spikelets and attached grains of head at main stem. 5) Maturing rate of both this main seem of whole plant body was remarkably lower than that of normal rice. 6) Akiochi rice showed lower head weight of main stem, total hulled rice weight, total grain yield, 1000-grain weight, straw weight and straw-hulled rice ratio. 2. Physical and chemical study on soil. 1) Akiochi soil showed thinner upper layer and total thickness of upper and lower parts was smaller than that of normal. 2) Akiochi soil of Suwon was mainly composed of sand, while that of Sosa and Pyungtak was composed of heavy clay. 3) Chemical analysis indicated that content of $SiO_2$ in upper layer is always lower than that of normal. But no other common tendencies were found. 4) This analysis further lillustrates lower content of Fe, & Mn at Suwon ; of Mn at Sosa and higher content of Fe at Sosa and organic matters at Pyungtak. 5) Some differences in the content of N in each plot could be marked though irregular. 3. Chemical Composition of plant body. 1) Chemical analysis on grain, boot leaf and straw did not suggest any remarkable differences between normal and Akiochi rice, except that the latter contains less Si in boot leaf and less Mn in straw. 2) Contents of each chemical element were measured in grain and straw to calculate the percentage of element content in grain to that of whole plant body including both grain and straw. Here, Akiochi rice always showed lower value in N, K and Mn. 4. Relationship between chemical composition of plant body and that of soil. Akiochi soil at Sosa marked lower content of Mn. This caused another lower content of this element in grain, boot leaf and straw. But except that, no remarkable relationship could be found in this study.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.270-271
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• 2015

본 논문은 추락 방지장치가 형성된 창문에 관한 것으로, 일반적인 형태의 공동주택 여닫이 창문은 사각틀 형태로 된 창틀의 내 창문이 슬라이드 가능하게 끼워져 있고, 창문을 개방 시, 창틀에 해충방지용 방충망이 설치되어 있지만, 종래의 방충망은 구조적으로 매우 취약하여 찢어지거나 휘면서 창틀로부터 쉽게 이탈되어 쉽게 추락사고가 발생하였다. 이러한 문제점을 해소하기 위해서 본 기술을 적용한 창문 설치 시, 개방했을 경우에만 체인 안전망이 형성되고, 창문을 닫았을 경우에는 체인 안전망이 창틀 또는 창문틀에 수용되어 보이지 않게 되어 미관을 해치지 않으면서도 추락 사고를 방지하여 안정성을 보장하는 효과를 거두었다.

• The Safety technology
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• no.145
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• pp.44-47
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• 2010

• The Safety technology
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• no.154
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• pp.44-47
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• 2010