• Title/Summary/Keyword: engineering problem

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An Experimental Study on the Evaluation of Shear Strength of Weathered Soil Containing Coarse Particles (굵은 입자가 포함된 풍화토의 전단강도 평가에 대한 실험연구)

  • Joon-Seok Kim
    • Journal of the Society of Disaster Information
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    • v.20 no.1
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    • pp.169-176
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    • 2024
  • Purpose: In this paper, an experimental study was conducted to analyze the difference in shear strength caused by the problem of excluding coarse particles due to the size of the test specimen in the direct shear test. Method: A large-scale direct shear test was conducted on three weathered soils containing coarse aggregates with a maximum diameter of 50mm. In addition, a small-scale direct shear test was performed using a sample with a maximum diameter of 5 mm, excluding coarse aggregates. Result: In the case of the small-scale direct shear test, compared to the results of the large-scale direct shear test containing large particles, the internal friction angle was about 2.3% smaller, and there was no significant difference. In terms of cohesion, compared to the large-scale direct shear test, the small-scale direct shear test derived about 80.3% smaller value, showing a relatively large difference. Conclusion: In the large-scale direct shear test, it was analyzed that the coarse particles had a greater impact on the cohesion than the internal friction angle. Therefore, granite weathered clay containing coarse particles is judged to have the same shear strength as the cohesive force that is not affected by vertical stress. In this study, it was analyzed that the small-scale direct shear test, which excludes the coarse particles that are commonly used, provides results on the safety side by excluding the effect of coarse particles.

Characteristics of the Carbon Capture and Utilization System in Methanol Fuel Propulsion Ships Based on the Hydrogen Fuel Cell Hybrid System (수소 연료전지 하이브리드 시스템 기반 메탄올 연료추진 선박에서 CCU 적용에 따른 시스템 특성 분석)

  • YoonHo Lee;JunHo Kim
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.30 no.2
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    • pp.239-251
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    • 2024
  • In this study, a hydrogen fuel cell process based on methanol was developed to reduce greenhouse gas emissions. In Case1, the methanol fuel engine system was designed to investigate the emission of exhaust gas when methanol was supplied as fuel instead of gasoline to the engine. In Case2, a hydrogen fuel cell system was designed by adding a methanol reforming system to Case1. This hybrid system produced gray hydrogen and combined the output of the engine and fuel cell to drive the ship. However, gray hydrogen emits carbon in the process of producing hydrogen. To address this problem, a carbon capture and utilization (CCU) system was added to Case3. The CO2 of the flue gas discharged from Case2 was synthesized with gray hydrogen to produce blue methanol. The results of the case studies revealed that the optimal operating conditions were 220 ℃, 500 kPa, SCR = 1.0, and flow ratio = 0.7. The system of Case3 reduced carbon emissions by 42% compared with that Case1. Thus, the hybrid system of Case3 could considerably reduce the ship's CO2 emissions.

Analysis of Causes of Increase in Construction Cost and Minimize Increase of Cost through Performance Evaluation of Public Construction Projects (공공건설사업의 성과평가를 통한 공사비 증가 원인 분석 및 증가 최소화 방안)

  • Moon, Hyunseok;Ryoo, Geunho;Hong, Hyunki
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.44 no.4
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    • pp.567-575
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    • 2024
  • The government and local governments are utilizing regulations, policies, and various project management techniques at each project stage to effectively and systematically manage public construction projects. However, the increase in construction costs continues to occur. In order to solve these problems, this study attempted to collect cases of existing public construction projects and analyze historical data. And it would like to derive the impact factor of increased construction costs. Based on the results, a plan was proposed to prevent the causes of increase and minimize in construction costs. The main reasons for the increase in costs were the occurrence of civil petition, differences between design documents and site conditions, and changes due to requests from the owner and changes in the business plan. And to solve these problems, this study proposed improvement for each cause from an institutional perspective, along with interview with experts and project owners. The results of this study are significant in improving the process of existing public construction process and presenting key inspection and review items for each major inspection stage in order to solve problem resulting from the analysis of the performance of public construction projects.

Evaluation of Quality Standards of Bio-Diesel (BD100, BD20) Manufactured Using Waste Frying Oil (폐식용유를 이용하여 제조한 바이오디젤(BD100, BD20)의 품질기준 평가)

  • Na, Seong-Joo;Jeon, Byung-Gwan
    • Journal of the Korea Organic Resources Recycling Association
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    • v.17 no.1
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    • pp.39-48
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    • 2009
  • Biodiesel is estimated to be the best recycling energy source as an alternative fuel for transportation vehicles which represents the biggest share of greenhouse effect gas exhausts. Thus, in order to widely expand use of biodiesel and to enhancement its reliability, studies on quality improvement of biodiesel is needed. In this study, we have produced biodiesel(BD100, BD20) through esterification reaction using raw material of waste frying oil and analyzed compatibility with 24 items of quality criteria. As waste frying oil has high contents of unsaturated fatty acid such as Oleic acid, Linoleic acid and Linolenic acid, it is confirmed that there is no problem in using the same as a raw material of biodiesel. The result of analyzing the quality criteria items of biodiesel showed that it satisfied all the quality criteria except the oxidation stability of BD100, which was 2 hours, fatty acid methyl ester of BD20, which was 18.6w% and the filter plugging point, which was $-5^{\circ}C$. We believe that it will contribute to improved utilization of waste resources as alternative energy if studies on technology to improve quality of some items are provided.

An Efficient Dual Queue Strategy for Improving Storage System Response Times (저장시스템의 응답 시간 개선을 위한 효율적인 이중 큐 전략)

  • Hyun-Seob Lee
    • Journal of Internet of Things and Convergence
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    • v.10 no.3
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    • pp.19-24
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    • 2024
  • Recent advances in large-scale data processing technologies such as big data, cloud computing, and artificial intelligence have increased the demand for high-performance storage devices in data centers and enterprise environments. In particular, the fast data response speed of storage devices is a key factor that determines the overall system performance. Solid state drives (SSDs) based on the Non-Volatile Memory Express (NVMe) interface are gaining traction, but new bottlenecks are emerging in the process of handling large data input and output requests from multiple hosts simultaneously. SSDs typically process host requests by sequentially stacking them in an internal queue. When long transfer length requests are processed first, shorter requests wait longer, increasing the average response time. To solve this problem, data transfer timeout and data partitioning methods have been proposed, but they do not provide a fundamental solution. In this paper, we propose a dual queue based scheduling scheme (DQBS), which manages the data transfer order based on the request order in one queue and the transfer length in the other queue. Then, the request time and transmission length are comprehensively considered to determine the efficient data transmission order. This enables the balanced processing of long and short requests, thus reducing the overall average response time. The simulation results show that the proposed method outperforms the existing sequential processing method. This study presents a scheduling technique that maximizes data transfer efficiency in a high-performance SSD environment, which is expected to contribute to the development of next-generation high-performance storage systems

Export Control System based on Case Based Reasoning: Design and Evaluation (사례 기반 지능형 수출통제 시스템 : 설계와 평가)

  • Hong, Woneui;Kim, Uihyun;Cho, Sinhee;Kim, Sansung;Yi, Mun Yong;Shin, Donghoon
    • Journal of Intelligence and Information Systems
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    • v.20 no.3
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    • pp.109-131
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    • 2014
  • As the demand of nuclear power plant equipment is continuously growing worldwide, the importance of handling nuclear strategic materials is also increasing. While the number of cases submitted for the exports of nuclear-power commodity and technology is dramatically increasing, preadjudication (or prescreening to be simple) of strategic materials has been done so far by experts of a long-time experience and extensive field knowledge. However, there is severe shortage of experts in this domain, not to mention that it takes a long time to develop an expert. Because human experts must manually evaluate all the documents submitted for export permission, the current practice of nuclear material export is neither time-efficient nor cost-effective. Toward alleviating the problem of relying on costly human experts only, our research proposes a new system designed to help field experts make their decisions more effectively and efficiently. The proposed system is built upon case-based reasoning, which in essence extracts key features from the existing cases, compares the features with the features of a new case, and derives a solution for the new case by referencing similar cases and their solutions. Our research proposes a framework of case-based reasoning system, designs a case-based reasoning system for the control of nuclear material exports, and evaluates the performance of alternative keyword extraction methods (full automatic, full manual, and semi-automatic). A keyword extraction method is an essential component of the case-based reasoning system as it is used to extract key features of the cases. The full automatic method was conducted using TF-IDF, which is a widely used de facto standard method for representative keyword extraction in text mining. TF (Term Frequency) is based on the frequency count of the term within a document, showing how important the term is within a document while IDF (Inverted Document Frequency) is based on the infrequency of the term within a document set, showing how uniquely the term represents the document. The results show that the semi-automatic approach, which is based on the collaboration of machine and human, is the most effective solution regardless of whether the human is a field expert or a student who majors in nuclear engineering. Moreover, we propose a new approach of computing nuclear document similarity along with a new framework of document analysis. The proposed algorithm of nuclear document similarity considers both document-to-document similarity (${\alpha}$) and document-to-nuclear system similarity (${\beta}$), in order to derive the final score (${\gamma}$) for the decision of whether the presented case is of strategic material or not. The final score (${\gamma}$) represents a document similarity between the past cases and the new case. The score is induced by not only exploiting conventional TF-IDF, but utilizing a nuclear system similarity score, which takes the context of nuclear system domain into account. Finally, the system retrieves top-3 documents stored in the case base that are considered as the most similar cases with regard to the new case, and provides them with the degree of credibility. With this final score and the credibility score, it becomes easier for a user to see which documents in the case base are more worthy of looking up so that the user can make a proper decision with relatively lower cost. The evaluation of the system has been conducted by developing a prototype and testing with field data. The system workflows and outcomes have been verified by the field experts. This research is expected to contribute the growth of knowledge service industry by proposing a new system that can effectively reduce the burden of relying on costly human experts for the export control of nuclear materials and that can be considered as a meaningful example of knowledge service application.

KNU Korean Sentiment Lexicon: Bi-LSTM-based Method for Building a Korean Sentiment Lexicon (Bi-LSTM 기반의 한국어 감성사전 구축 방안)

  • Park, Sang-Min;Na, Chul-Won;Choi, Min-Seong;Lee, Da-Hee;On, Byung-Won
    • Journal of Intelligence and Information Systems
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    • v.24 no.4
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    • pp.219-240
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    • 2018
  • Sentiment analysis, which is one of the text mining techniques, is a method for extracting subjective content embedded in text documents. Recently, the sentiment analysis methods have been widely used in many fields. As good examples, data-driven surveys are based on analyzing the subjectivity of text data posted by users and market researches are conducted by analyzing users' review posts to quantify users' reputation on a target product. The basic method of sentiment analysis is to use sentiment dictionary (or lexicon), a list of sentiment vocabularies with positive, neutral, or negative semantics. In general, the meaning of many sentiment words is likely to be different across domains. For example, a sentiment word, 'sad' indicates negative meaning in many fields but a movie. In order to perform accurate sentiment analysis, we need to build the sentiment dictionary for a given domain. However, such a method of building the sentiment lexicon is time-consuming and various sentiment vocabularies are not included without the use of general-purpose sentiment lexicon. In order to address this problem, several studies have been carried out to construct the sentiment lexicon suitable for a specific domain based on 'OPEN HANGUL' and 'SentiWordNet', which are general-purpose sentiment lexicons. However, OPEN HANGUL is no longer being serviced and SentiWordNet does not work well because of language difference in the process of converting Korean word into English word. There are restrictions on the use of such general-purpose sentiment lexicons as seed data for building the sentiment lexicon for a specific domain. In this article, we construct 'KNU Korean Sentiment Lexicon (KNU-KSL)', a new general-purpose Korean sentiment dictionary that is more advanced than existing general-purpose lexicons. The proposed dictionary, which is a list of domain-independent sentiment words such as 'thank you', 'worthy', and 'impressed', is built to quickly construct the sentiment dictionary for a target domain. Especially, it constructs sentiment vocabularies by analyzing the glosses contained in Standard Korean Language Dictionary (SKLD) by the following procedures: First, we propose a sentiment classification model based on Bidirectional Long Short-Term Memory (Bi-LSTM). Second, the proposed deep learning model automatically classifies each of glosses to either positive or negative meaning. Third, positive words and phrases are extracted from the glosses classified as positive meaning, while negative words and phrases are extracted from the glosses classified as negative meaning. Our experimental results show that the average accuracy of the proposed sentiment classification model is up to 89.45%. In addition, the sentiment dictionary is more extended using various external sources including SentiWordNet, SenticNet, Emotional Verbs, and Sentiment Lexicon 0603. Furthermore, we add sentiment information about frequently used coined words and emoticons that are used mainly on the Web. The KNU-KSL contains a total of 14,843 sentiment vocabularies, each of which is one of 1-grams, 2-grams, phrases, and sentence patterns. Unlike existing sentiment dictionaries, it is composed of words that are not affected by particular domains. The recent trend on sentiment analysis is to use deep learning technique without sentiment dictionaries. The importance of developing sentiment dictionaries is declined gradually. However, one of recent studies shows that the words in the sentiment dictionary can be used as features of deep learning models, resulting in the sentiment analysis performed with higher accuracy (Teng, Z., 2016). This result indicates that the sentiment dictionary is used not only for sentiment analysis but also as features of deep learning models for improving accuracy. The proposed dictionary can be used as a basic data for constructing the sentiment lexicon of a particular domain and as features of deep learning models. It is also useful to automatically and quickly build large training sets for deep learning models.

Evaluation of Nutrient Discharges from Greenhouses with Flooding Soil Surface at Two Different Locations (입지조건이 다른 시설재배지에서 담수처리에 따른 양분 용탈량 평가)

  • Kim, Min-Kyeong;Roh, Kee-An;Ko, Byong-Gu;Park, Seong-Jin;Jung, Goo-Bok;Lee, Deog-Bae;Kim, Chul-Soo
    • Korean Journal of Soil Science and Fertilizer
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    • v.43 no.3
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    • pp.315-321
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    • 2010
  • Greenhouse soil cultivated with excessive compost and chemical fertilizer has been an issue to deteriorate soil and water quality in the environment. The objective of this study was to evaluate the nutrient outflow by desalting method, flooding soil surface, after vegetable cropping in greenhouse soils. Field experiment from July to September 2008, was conducted to quantify greenhouse locations, i.e. alluvial plain and local valley. The changes of desalinization in both locations were higher as the amounts of irrigated and drained water were increased. Particularly, the ratio of desalinization in alluvial plain was much higher (66.7%) than the one in local valley (45.6%). However, $NH_4$-N contents of local valley soil during the flooding were higher than in those of alluvial plain. This was caused by high total nitrogen and organic matter in local valley soil than those in alluvial plain soil. With comparing to the input and output loads of T-N and T-P in greenhouses with local valley and alluvial plain soils, the output loads of nutrients were larger than the input loads of nutrients. This result showed that the flooding soil surface can be a good treatment to desalinize greenhouse soils. However, this conclusion remained that the flooding water containing high N and P concentrations might cause the secondary effect on the quality of streams and groundwater since excessive nutrient concentrations can be the main cause of eutrophication problem in aquatic environment.

Jeju Shinyang Fishing Port Remodeling Plan Utilizing Marine Tourism Resources (해양관광자원을 활용한 제주 신양항 리모델링 계획)

  • Kim, Yelim;Sung, Jong-Sang
    • Journal of the Korean Institute of Landscape Architecture
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    • v.44 no.2
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    • pp.52-69
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    • 2016
  • The fishing port was once the foothold of production as well as the stronghold of communities but with the declining of the fishing industry, ports became abandoned space. Jeju Special Self-Governing Province has continued its effort to vitalize marine tourism since 2010. Shinyang Port in particular is designated as a Prearranged Marina Port Development Zone, and planning for the Jeju Ocean Marina City project is underway. Nevertheless, fishing port remodeling projects implemented on Jeju so far have focused only on civil engineering such as renovating old facilities. In addition, most Marina Port Development Projects have been irrelevant to local communities. Leading projects by the local government mostly suffer from a lack of funding, which results in the renovation of old facilities and improper maintenance, while private sector investment projects do not lead to benefit sharing with the community. Shinyang Port, also renovated in 2008, ended up with outer breakwater extension construction that neither solved the fundamental problem of the site nor gave benefits to residents. To arrange a way to solve problems for civil engineering focused development project, improper maintenance, and benefit sharing with community, first, this study proposes a development plan that connects with the outlying areas near the ports. The plan reflects existing topography, Jeju traditional stonewalls, narrow paths on the master plan and programs by reading the regional context. In this way, this paper suggests a space development plan reflecting the local landscape and characteristic factors. Second, it satisfies various needs by using existing and new Marine Tourism Resources. Third, it examines sustainable operation and management measures through residents' participation. The proposal is significant in two key ways: it is a fresh attempt at connecting the fishing port with its outlying areas from a landscape perspective; and it considers environmental, social, economic issues, and suggests participation for local communities. Thus, the model can be used in future fishing-port remodeling plans for revitalizing unused space, including invaluable traditional landscapes, and for boosting the marine-leisure industry.

Rural Survey on Agricultural Mechanization Project - Rice Transplantation Operation - (농업기계화(農業機械化)에 관(關)한 연구(硏究) - 수도이앙작업(水稻移秧作業)의 기계화(機械化)를 중심(中心)으로 -)

  • Ahn, Su Bong;Kim, Soung Rai;Kim, Ki Dae
    • Korean Journal of Agricultural Science
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    • v.8 no.2
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    • pp.203-211
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    • 1981
  • Mechanization of rice transplanting operation is very important project not only to solve the labor shortage problem at the so-called labor demand peak seasons of the rice transplanting, but also to reduce the production cost of rice by reducing the labor requirements. For these reasons this study was carried out to find the basic data for encourage the project of mechanization of rice transplanting. 381 sample farms were surveyed with questionaries and interviewed with a considerable number of relative personels about the operation, selecting and ownership trend of the rice transplanter. Collected data was analized by computer of Chungnam National University computer center applied to frequencies, cross- tabulation, $x^2$-test. The analized results of this survey are summarized as follows; 1. About 76.09% of the farmers interviewed was individual ownership of rice transplanter but about 52.27% of the farmers who wanted to purchase it in 2 or 3 years supported the cooperative ownership and utilization. This fact suggested that cooperative system of village level should be thoroghly studied. 2. The 93.33% of respondents gave the answer that the yield of rice was not affected by the planting methods between machine and manual. 3. The farmers who had a rice transplanter owned 4- row type rice transplanter with mat type seedling but the 25% of the farmers wanted to purchase it in 2 or 3 years wanted to own a 4 row type rice transplanter with band type seedling. Therefore the introduction of the 4-row type rice transplanter with band type seedling to rural area should be considered again. 4. The percent of farmers who wanted the cooperative system of village level was 49.57-57.83% of the farmers who had it already and wanted to own it in near future. It was strengthened by this fact that seedling nursely work was technically supported by the governmental level.

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