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A Study on the Risk Assessment and Improvement Methods Based on Hydrogen Explosion Accidents of a Power Plant and Water Electrolysis System (발전소 및 수전해 시스템의 수소 폭발 사고 사례 기반 위험성 평가 및 개선 방안 연구)

  • MIN JAE JEON;DAE JIN JANG;MIN CHUL LEE
    • Journal of Hydrogen and New Energy
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    • v.35 no.1
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    • pp.66-74
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    • 2024
  • This study addresses the escalating issue of worldwide hydrogen gas accidents, which has seen a significant increase in occurrences. To comprehensively evaluate the risks associated with hydrogen, a two approach was employed in this study. Firstly, a qualitative risk assessment was conducted using the bow-tie method. Secondly, a quantitative consequence analysis was carried out utilizing the areal locations of hazardous atmospheres (ALOHA) model. The study applied this method to two incidents, the hydrogen explosion accident occurred at the Muskingum River power plant in Ohio, USA, 2007 and the hydrogen storage tank explosion accident occurred at the K Technopark water electrolysis system in Korea, 2019. The results of the risk assessments revealed critical issues such as deterioration of gas pipe, human errors in incident response and the omission of important gas cleaning facility. By analyzing the cause of accidents and assessing risks quantitatively, the effective accident response plans are proposed and the effectiveness is evaluated by comparing the effective distance obtained by ALOHA simulation. Notably, the implementation of these measures led to a significant 54.5% reduction in the risk degree of potential explosions compared to the existing risk levels.

Adsorption process efficiency of activated carbon from date pits in removing pollutants from dye wastewater

  • A. Ahsan;I.K. Erabee;F.B. Nazrul;M. Imteaz;M.M. El-Sergany;S. Shams;Md. Shafiquzzaman
    • Membrane and Water Treatment
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    • v.14 no.4
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    • pp.163-173
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    • 2023
  • The presence of high amounts of organic and inorganic contaminants in textile wastewater is a major environmental concern. Therefore, the treatment of textile wastewater is an urgent issue to save the aquatic environment. The disposal of large quantities of untreated textile wastewater into inland water bodies can cause serious water pollution. In this study, synthetic dye wastewater samples were prepared using orange dye in the laboratory. The synthetic samples were then treated by a batch adsorption process using the prepared activated carbon (AC) from date pits. The wastewater parameters studied were the pH, total dissolved solids (TDS), total suspended solids (TSS), electrical conductivity (EC) and salinity. The activated adsorption process showed that the maximum removal efficiencies of electric conductivity (EC), salinity, TDS and TSS were 65%, 92%, 89% and 90%, respectively. The removal efficiencies were proportional to the increase in contact time (30-120 min) and AC adsorbent dose (1, 3 and 5 g/L). The adsorption profile indicates that 5 g/L of adsorbent delivers better results for TDS, EC, TSS and salinity at contact time of 120 min. The adsorption characteristics are better suited to the pseudo-second-order kinetic model than to the pseudo-first-order kinetic model. The Langmuir and Freundlich isotherms were well suited for describing the adsorption or contact behavior of EC and TSS within the studied system.

An Examination of a Risk Assessment Method and Analysis of Defect Types of Apartment Finishing Works (공동주택 마감공사의 하자유형별 분석 및 위험성 평가 방법에 관한 연구)

  • Son, Seunghyun;Lee, Jae-hyeon;Son, Kiyoung
    • Journal of the Korea Institute of Building Construction
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    • v.24 no.2
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    • pp.249-260
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    • 2024
  • In recent years, the proportion of medium and small-sized apartments within the housing market has seen a noticeable increase, alongside a corresponding rise in disputes related to construction defects. Such disputes are most prevalent in the finishing works phase of construction, which not only are frequent in occurrence but also impose significant repair costs. Furthermore, there is a noticeable scarcity of research focused on the quality management of finishing work defects prior to the completion of construction. Addressing this issue necessitates a methodology capable of preemptively identifying defects by analyzing their frequency and associated costs across various defect types. Consequently, the aim of this study is to propose a risk assessment methodology by conducting an analysis of defect cases across 3,299 apartment units, considering aspects such as frequency and severity. The outcomes of this research endeavor are expected to offer practical management strategies to enhance the quality of apartment finishing works and serve as an academic foundation for the enhancement of construction management systems pertaining to apartment finishing works.

Analysis of Ammunition Inspection Record Data and Development of Ammunition Condition Code Classification Model (탄약검사기록 데이터 분석 및 탄약상태기호 분류 모델 개발)

  • Young-Jin Jung;Ji-Soo Hong;Sol-Ip Kim;Sung-Woo Kang
    • Journal of the Korea Safety Management & Science
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    • v.26 no.2
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    • pp.23-31
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    • 2024
  • In the military, ammunition and explosives stored and managed can cause serious damage if mishandled, thus securing safety through the utilization of ammunition reliability data is necessary. In this study, exploratory data analysis of ammunition inspection records data is conducted to extract reliability information of stored ammunition and to predict the ammunition condition code, which represents the lifespan information of the ammunition. This study consists of three stages: ammunition inspection record data collection and preprocessing, exploratory data analysis, and classification of ammunition condition codes. For the classification of ammunition condition codes, five models based on boosting algorithms are employed (AdaBoost, GBM, XGBoost, LightGBM, CatBoost). The most superior model is selected based on the performance metrics of the model, including Accuracy, Precision, Recall, and F1-score. The ammunition in this study was primarily produced from the 1980s to the 1990s, with a trend of increased inspection volume in the early stages of production and around 30 years after production. Pre-issue inspections (PII) were predominantly conducted, and there was a tendency for the grade of ammunition condition codes to decrease as the storage period increased. The classification of ammunition condition codes showed that the CatBoost model exhibited the most superior performance, with an Accuracy of 93% and an F1-score of 93%. This study emphasizes the safety and reliability of ammunition and proposes a model for classifying ammunition condition codes by analyzing ammunition inspection record data. This model can serve as a tool to assist ammunition inspectors and is expected to enhance not only the safety of ammunition but also the efficiency of ammunition storage management.

An Experiment Study on Electric Vehicle Fire and Fire Response Procedures (전기차 화재 실험 및 대응방안에 관한 연구)

  • Ki-Hun Nam;Jun-Sik Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.27 no.1
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    • pp.63-70
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    • 2024
  • Lithium-ion batteries (LIB) are widely used in various sectors, such as transportation (e.g., electric vehicles (EV)) and energy (e.g., energy storage facilities) due to their high energy density, broad operating temperature (-20 ℃ ~ 60 ℃), and high capacities. LIBs are powerful but fragile on external factors, including pressure, physical damage, overheating, and overcharging, that cause thermal runaway causing fires and explosions. During a LIB fire, a large amount of oxygen is generated from the decomposition of ionogenic materials. A water fire extinguisher that helps with cooling and suffocating must be essentially required at the same time. In fact, however, it is difficult to suppress LIB fires in the case of EVs because a LIB is installed with a battery pack housing that interrupts direct extinguishing by water. Thus, this study aims to investigate effective fire extinguishing measurements for LIB fires by using an EV. Relevant documents, including research articles and reports, were reviewed to identify effective ways of LIBs fire extinguishing. A real-scale fire experiment generating thermal runaway was carried out to figure out the combustion characteristics of EVs. This study revealed that the most effective fire extinguishing measurements for LIB fires are applying fire blankets and water tanks. However, there is still a lack of adequate regulation and guidelines for LIB fire extinguishment. Taking this into account, developing functional fire extinguishment measurements and available regulatory instruments is an urgent issue to secure the safety of firefighters and citizens.

Revascularization Strategies in Patients With ST-Segment Elevation Myocardial Infarction and Multivessel Disease: Is FFR-Guided Strategy Still Valuable?

  • Doosup Shin;Tae-Min Rhee;Seung Hun Lee ;Joo Myung Lee
    • Korean Circulation Journal
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    • v.52 no.4
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    • pp.280-287
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    • 2022
  • Several studies have shown the benefit of complete revascularization (CR) over culprit-only percutaneous coronary intervention (PCI) in patients with ST-segment elevated myocardial infarction (STEMI) and multivessel disease (MVD). Nevertheless, optimal strategy to select targets for non-culprit PCI has not been clarified. In this paper, we critically discuss and compare the safety and efficacy of different strategies for CR in patients with STEMI and MVD using a Bayesian network meta-analysis including all previous randomized controlled trials (RCTs). In Bayesian network meta-analysis of 13 RCTs, culprit-only PCI was associated with higher risk of major adverse cardiac events (MACE), compared with angiography-guided or fractional flow reserve (FFR)-guided CR strategies. However, there was no significant difference between angiography-guided and FFR-guided CR strategies in the risk of MACE and its individual components including all-cause death, cardiac death, myocardial infarction (MI), and revascularization. These evidence support that both angiography-guided and FFR-guided complete revascularization strategies would be reasonable treatment option in patients with STEMI and MVD. If the non-culprit lesion is severe on visual assessment, angiography-guided PCI can be considered. If the non-culprit lesion is intermediate in severity or unclear based on visual assessment, FFR-guided strategy can be used as a reliable and objective tool, providing similar benefits with less stents compared with an angiography-guided strategy. Further RCT is needed to evaluate direct comparison between angiography-guided and FFR-guided CR strategies in patients with STEMI and MVD. Ongoing FRAME-AMI trial (NCT02715518) will provide more evidence regarding this issue.

Integrative Assessment of High-Speed Railway System Vulnerability to Future Climate-Induced Flooding in China

  • Hengliang Wu;Bingsheng Liu;Jingke Hong;Yifei Wang
    • International conference on construction engineering and project management
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    • 2024.07a
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    • pp.127-136
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    • 2024
  • Flooding presents a significant threat to infrastructure, and climate change is exacerbating these risks. High-speed rail (HSR) infrastructure, designed based on historical data, may struggle to cope with future extreme flood events. Infrastructure stakeholders require forecasting capabilities to predict the intensity and frequency of future floods so they can develop adaptive strategies to mitigate flood risks and impacts. Floods can cause significant damage to HSR infrastructure networks, disrupting their operations. Traditional network theory-based frameworks are insufficient for analyzing the three-dimensional effects of floods on HSR networks. To address this issue, this study proposes a comprehensive approach to assess flood risk and vulnerability under future climate scenarios for HSR networks. The method consists of three components. (i) Generate flood inundation data by utilizing global climate models, Shared Socioeconomic Pathways(SSPs), and the CaMa-Flood model. (ii) Fit extreme flood depths to the Gumbel distribution to generate flood inundation scenarios. (iii) Overlay flood scenarios on the HSR network and quantitatively assess network vulnerability based on topology network. When applied to the HSR system in mainland China, the results indicate that flood severity does not necessarily increase under higher SSPs, but may worsen over time. The minimum flood return period that causes HSR disruptions is decreasing, with Hubei Province showing a significant increase in HSR segment failure probability. Discontinuous phase transitions in HSR network topology metrics suggest potential nationwide collapses under future infrequent floods. These findings can inform preventive measures for the HSR sector and flood-resistant standards for HSR infrastructure. The method used in this study can be extended to analyze the vulnerability of other transportation systems to natural disasters, serving as a quantitative tool for improving resilience in a changing climate.

The Current Status of the Warsaw Convention and Subsequent Protocols in Leading Asian Countries (아시아 주요국가(主要國家)들에 있어서의 바르샤바 체제(體制)의 적용실태(適用實態)와 전망(展望))

  • Lee, Tae-Hee
    • The Korean Journal of Air & Space Law and Policy
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    • v.1
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    • pp.147-162
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    • 1989
  • The current status of the application and interpretation of the Warsaw Convention and its subsequent Protocols in Asian countries is in its fredgling stages compared to the developed countries of Europe and North America, and there is thus little published information about the various Asian governments' treatment and courts' views of the Warsaw System. Due to that limitation, the accent of this paper will be on Korea and Japan. As one will be aware, the so-called 'Warsaw System' is made up of the Warsaw Convention of 1929, the Hague Protocol of 1955, the Guadalajara Convention of 1961, the Guatemala City Protocol of 1971 and the Montreal Additional Protocols Nos. 1,2,3 and 4 of 1975. Among these instruments, most of the countries in Asia are parties to both the Warsaw Convention and the Hague Protocol. However, the Republic of Korea and Mongolia are parties only to the Hague Protocol, while Burma, Indonesia and Sri Lanka are parties only to the Warsaw Convention. Thailand and Taiwan are not parties only to the convention or protocol. Among Asian states, Indonesia, the Phillipines and Pakistan are also parties to the Guadalajara Convention, but no country in Asia has signed the Guatemala City Protocol of 1971 or the Montreal Additional Protocols, which Protocols have not yet been put into force. The People's Republic of China has declared that the Warsaw Convention shall apply to the entire Chinese territory, including Taiwan. 'The application of the Warsaw Convention to one-way air carriage between a state which is a party only to the Warsaw Convention and a state which is a party only to the Hague Protocol' is of particular importance in Korea as it is a signatory only to the Hague Protocol, but it is involved in a great deal of air transportation to and from the united states, which in turn is a party only to the Warsaw Convention. The opinion of the Supreme Court of Korea appears to be, that parties to the Warsaw Convention were intended to be parties to the Hague Protocol, whether they actually signed it or not. The effect of this decision is that in Korea the United States and Korea will be considered by the courts to be in a treaty relationship, though neither State is a signatory to the same instrument as the other State. The first wrongful death claim in Korea related to international carriage by air under the Convention was made in Hyun-Mo Bang, et al v. Korean Air Lines Co., Ltd. case. In this case, the plaintiffs claimed for damages based upon breach of contract as well as upon tort under the Korean Civil Code. The issue in the case was whether the time limitation provisions of the Convention should be applicable to a claim based in tort as well as to a claim based in contract. The Appellate Court ruled on 29 August 1983 that 'however founded' in Article 24(1) of the Convention should be construed to mean that the Convention should be applicable to the claim regardless of whether the cause of action was based in tort or breach of contract, and that the plaintiffs' rights to damages had therefore extinguished because of the time limitation as set forth in Article 29(1) of the Convention. The difficult and often debated question of what exactly is meant by the words 'such default equivalent to wilful misconduct' in Article 25(1) of the Warsaw Convention, has also been litigated. The Supreme Court of Japan dealt with this issue in the Suzuki Shinjuten Co. v. Northwest Airlines Inc. case. The Supreme Court upheld the Appellate Court's ruling, and decided that 'such default equivalent to wilful misconduct' under Article 25(1) of the Convention was within the meaning of 'gross negligence' under the Japanese Commercial Code. The issue of the convention of the 'franc' into national currencies as provided in Article 22 of the Warsaw Convention as amended by the Hague Protocol has been raised in a court case in Korea, which is now before the District Court of Seoul. In this case, the plaintiff argues that the gold franc equivalent must be converted in Korean Won in accordance with the free market price of gold in Korea, as Korea has not enacted any law, order or regulation prescribing the proper method of calculating the equivalent in its national currency. while it is unclear if the court will accept this position, the last official price of gold of the United States as in the famous Franklin Mint case, Special Drawing Right(SDR) or the current French franc, Korean Air Lines has argued in favor of the last official price of gold of the United States by which the air lines converted such francs into us Dollars in their General Conditions of Carriage. It is my understanding that in India, an appellate court adopted the free market price valuation. There is a report as well saying that if a lawsuit concerning this issue were brought in Pakistan, the free market cost of gold would be applied there too. Speaking specifically about the future of the Warsaw System in Asia though I have been informed that Thailand is actively considering acceding to the Warsaw Convention, the attitudes of most Asian countries' governments towards the Warsaw System are still wnot ell known. There is little evidence that Asian countries are moving to deal concretely with the conversion of the franc into their own local currencies. So too it cannot be said that they are on the move to adhere to the Montreal Additional Protocols Nos. 3 & 4 which attempt to basically solve many of the current problems with the Warsaw System, by adopting the SDR as the unit of currency, by establishing the carrier's absolute liability and an unbreakable limit and by increasing the carrier's passenger limit of liability to SDR 100,000, as well as permiting the domestic introduction of supplemental compensation. To summarize my own sentiments regarding the future, I would say that given the fact that Asian air lines are now world leaders both in overall size and rate of growth, and the fact that both Asian individuals and governments are becoming more and more reliant on the global civil aviation networks as their economies become ever stronger, I am hopeful that Asian nations will henceforth play a bigger role in ensuring the orderly and hasty development of a workable unified system of rules governing international commercial air carriage.

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The Relationship between Korean college students' Self-Construal and Alexithymia: Mediation Effects of Ambivalence over Emotional Expressiveness and Emotion Suppression according to the Deficiency of Independent Self-Construal (한국 대학생의 자기관과 감정표현불능증의 관계: 상호독립적 자기관 결핍에 따른 정서표현양가성 및 정서억제의 매개 효과)

  • Soyoung Kwon;Jarang Kwak;Bia Kim;Donghoon Lee
    • Korean Journal of Culture and Social Issue
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    • v.25 no.2
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    • pp.101-118
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    • 2019
  • Alexithymia refers to a psychological deficit of identifying and describing one's feelings. It has benn reported that the level of alexithymia of East-Asians is generally higher than that of Western Europeans. Recently one research conducted in U.S. suggested that the interdependent self-construal from East-Asians' collectivism culture might be a cause of this cross-cultural difference. In the current study, we examined the relationship between the level of independent and interdependent self-construal of Korean college students and their level of alexithymia, as well as their ambivalence over emotional expressiveness and emotion suppression. The correlation analysis shows that the Korean students' alexithymia level does not correlate with their level of interdependent self-construal, but negatively correlates with their level of independent self-construal. Moreover, it is also correlated with the level of ambivalence over emotional expressiveness(AEE) and emotion suppression(ES). Thus, we setup a double-mediation model between the deficiency of independent self-construal and alexithymia via AEE and ES, and estimate mediation effects using Hayes and Preacher(2014)s' Process analysis. The results show that the deficiency of independent self-construal has a direct effect as well as indirect effects of AEE and ES on the alexithymia level. Further analysis on the indirect effects reveals that the mediation effect of AEE and the double mediation effect of ES via AEE are significant, but the mediation effect of ES is not significant. Current results imply that the interdependent self-construal from the traditional collectivistic culture may not cause Korean college students' problems on the emotional expression, but the relatively lower independent self-construal may cause them. The deficiency of independent self-constural may raise up the level of self-defensive ambivalence over emotional expressiveness and suppress emotional expression by themselves, which can result in alexithymia.

An Examination into the Illegal Trade of Cultural Properties (문화재(文化財)의 국제적 불법 거래(不法 去來)에 관한 고찰)

  • Cho, Boo-Keun
    • Korean Journal of Heritage: History & Science
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    • v.37
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    • pp.371-405
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    • 2004
  • International circulation of cultural assets involves numerous countries thereby making an approach based on international law essential to resolving this problem. Since the end of the $2^{nd}$ World War, as the value of cultural assets evolved from material value to moral and ethical values, with emphasis on establishing national identities, newly independent nations and former colonial states took issue with ownership of cultural assets which led to the need for international cooperation and statutory provisions for the return of cultural assets. UNESCO's 1954 "Convention for the Protection of Cultural Property in the Event of Armed Conflict" as preparatory measures for the protection of cultural assets, the 1970 "Convention on the Means of Prohibiting and Preventing the Illicit Import and Transfer of Ownership of Cultural Property" to regulate transfer of cultural assets, and the 1995 "Unidroit Convention on Stolen or Illegally Exported Cultural Objects" which required the return of illegally acquired cultural property are examples of international agreements established on illegal transfers of cultural assets. In addition, the UN agency UNESCO established the Division of Cultural Heritage to oversee cultural assets related matters, and the UN since its 1973 resolution 3187, has continued to demonstrate interest in protection of cultural assets. The resolution 3187 affirms the return of cultural assets to the country of origin, advises on preventing illegal transfers of works of art and cultural assets, advises cataloguing cultural assets within the respective countries and, conclusively, recommends becoming a member of UNESCO, composing a forum for international cooperation. Differences in defining cultural assets pose a limitation on international agreements. While the 1954 Convention states that cultural assets are not limited to movable property and includes immovable property, the 1970 Convention's objective of 'Prohibiting and preventing the illicit import, export and transfer of ownership of cultural property' effectively limits the subject to tangible movable cultural property. The 1995 Convention also has tangible movable cultural property as its subject. On this point, the two conventions demonstrate distinction from the 1954 Convention and the 1972 Convention that focuses on immovable cultural property and natural property. The disparity in defining cultural property is due to the object and purpose of the convention and does not reflect an inherent divergence. In the case of Korea, beginning with the 1866 French invasion, 36 years of Japanese colonial rule, military rule and period of economic development caused outflow of numerous cultural assets to foreign countries. Of course, it is neither possible nor necessary to have all of these cultural properties returned, but among those that have significant value in establishing cultural and historical identity or those that have been taken symbolically as a demonstration of occupational rule can cause issues in their return. In these cases, the 1954 Convention and the ratification of the first legislation must be actively considered. In the return of cultural property, if the illicit acquisition is the core issue, it is a simple matter of following the international accords, while if it rises to the level of diplomatic discussions, it will become a political issue. In that case, the country requesting the return must convince the counterpart country. Realizing a response to the earnest need for preventing illicit trading of cultural assets will require extensive national and civic societal efforts in the East Asian area to overcome its current deficiencies. The most effective way to prevent illicit trading of cultural property is rapid circulation of information between Interpol member countries, which will require development of an internet based communication system as well as more effective deployment of legislation to prevent trading of illicitly acquired cultural property, subscription to international conventions and cataloguing collections.