• Advances in environmental research
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• 제12권2호
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• pp.77-93
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• 2023

The water can be contaminated by natural sources or by industrial effluents. One such contaminant is fluoride. Fluoride contamination in the water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Among the commonly used treatment technologies applied for fluoride removal, the adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review paper the recent developments in fluoride removal from surface water by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. Various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to an industrial scale. Regeneration studies need to be performed to more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, technical strategies of the adsorption method including the Nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these strategies can greatly improve the removal efficiency of fluoride in water and guide the development of new efficient methods for fluoride removal in the future. This paper describes brief discussions on various low-cost adsorbents used for the effective removal of fluoride from water.

• Korean Journal of Radiology
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• 제24권8호
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• pp.719-728
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• 2023

Radiofrequency ablation (RFA) has been widely used to manage hepatocellular carcinomas (HCCs) equal to or smaller than 3 cm. No-touch RFA has gained attention and has recently been implemented in local ablation therapy for HCCs, despite its technical complexity, as it provides improved local tumor control compared to conventional tumor-puncturing RFA. This article presents the practice guidelines for performing no-touch RFA for HCCs, which have been endorsed by the Korean Society of Image-Guided Tumor Ablation (KSITA). The guidelines are primarily designed to assist interventional oncologists and address the limitations of conventional tumor-puncturing RFA with describing the fundamental principles, various energy delivery methods, and clinical outcomes of no-touch RFA. The clinical outcomes include technical feasibility, local tumor progression rates, survival outcomes, and potential complications.

• Journal of Gastric Cancer
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• 제24권1호
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• pp.57-68
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• 2024

Reduced-port gastrectomy (RPG) includes all procedures derived from various efforts to minimize surgical invasiveness, with single-incision laparoscopic gastrectomy (SILG) being the ultimate reduced-port technique. However, there are challenges related to its feasibility, oncological validity, training, and education. This review describes the current issues and challenges, as well as the future prospects of RPG for gastric cancer. Gastrectomy, which started as an open surgery, has evolved into a laparoscopic surgery. With the advancements in laparoscopic technology, SILG has been used to minimize surgical scarring. However, owing to the technical difficulties of SILG, cases involving the addition of 1 trocar or needle grasper alongside the multichannel port have also been reported. Additionally, 3-port laparoscopic gastrectomy (3PLG) using only 3 trocars is also being performed. RPG, as a concept, includes a range of approaches such as SILG, 2-port laparoscopic gastrectomy, and 3PLG. These techniques aimed to reduce the number of ports or incisions required for laparoscopic gastrectomy. Despite technical difficulties, RPGs offer numerous advantages, including minimal invasiveness, excellent cosmetic outcomes, and the potential for improved postoperative recovery, such as reduced length of hospital stay and post-operative pain. It could be considered similar to conventional laparoscopic gastrectomy, and may not be oncologically inferior. Ongoing studies, such as the KLASS 12, are required to gain further insights.

• Environmental Engineering Research
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• 제15권3호
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• pp.163-166
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• 2010

Pulp and paper mill wastewater has been treated by biological treatment, but the secondary effluent still contains high lignin, chemical oxygen demand, color and total dissolved solids. Tertiary treatment by land application, referred to as 'Project Green,' has been implemented to treat such high quantities of undesirable matters. The impacts of seepage from Project Green diffusing into receiving streams on the water quality and fish pen aquaculture were studied via the integration of technical and social approaches. The determination of the water quality was performed for 13 sampling stations along the receiving stream, including the Chot stream, Chot lagoon and the Pong River. The water quality was generally at normal levels, with the exception of total dissolved solids. The levels of matter were higher at the Chot stream, but became more diluted at the Chot lagoon and the Pong River, respectively. The social approach was conducted through the voluntary participation of the villagers as research assistants for the fish aquaculture study. Fish could grow at three fish pens within the study sites at the location of Project Green, the Chot lagoon and the Pong River. Fish growth at the Chot lagoon was better at the site of Project Green and the Pong River. The integration of technical and social approaches was a meaningful tool not only for the technical feasibility but in helping to solve the conflict between the community and industry.

• 한국문헌정보학회지
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• 제7권
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• pp.3-67
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• 1980

Because of the changes made in the modes of cataloguing and classification in its long history, the present catalogue of the National Central Library has become complicated and provides an inadequate guide to its collection. There can be no doubt that this is a serious deficiency in a closed access library since materials housed in the library are virtually inaccessible to unskilled readers. The whole breakdown of the efficiency of the catalogue is emminent and will ultimately create the most serious problems for the library. The main purpose of this survey is: (a) to identify problem areas created by the frequent changes in the cataloguing and classifying principles in the library and (b) to grope a rational direction for the future development. Analysing the various classification schemes and cataloguing rules adopted in processing materials (mainly books) in the library, the following conclusions have been made. A. The library adopted five different clasification schemes in different periods, of which KDCP was used for the most part of its collection. KDCP is recommended to use for the future colletion. A classification development office is recommended to be established within the library, of which the main function is to revise the KDCP in collaboration with the appropriate committee of the Korean Library Association. B. The present practice in the library is to apply three different cataloguing rules and two different author notation tables to the Oriental, classical, and Western collections. Efforts should be made to find out an efficient system so that this variety is simplified. An alphabetical index should be added to the classified catalogue, and improvements are required in the Japanese collection. C. The technical services division is inadequately staffed. The staff should be sufficiently numerous and specially qualified. D. The present financial support for the technical services of the library is inadequate. Sufficient financial provision should be made to ensure the effective work. E. A feasibility study should be carried out to develop a computer processing system for providing machine-readable catalogue records on magnetic tape for use by the library community in Korea.

• Earthquakes and Structures
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• 제4권5호
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• pp.451-470
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• 2013

It generally accepted that most building structures shall exhibit a nonlinear response when subjected to medium-high intensity earthquakes. It is currently known, however, that this phenomenon is not properly modelled in the majority of cases, especially at the design stage, where only simple linear methods have effectively been used. Recently, as a result of the exponential progress of computational tools, nonlinear modelling and analysis have gradually been brought to a more promising level. A wide range of modelling alternatives developed over the years is hence at the designer's disposal for the seismic design and assessment of engineering structures. The objective of the study presented herein is to test some of these models in an existing structure, and observe their performance in nonlinear static and dynamic analyses. This evaluation is done by the use of two of a known range of advanced computer programs: SAP2000 and SeismoStruct. The different models will focus on the element flexural mechanism with both lumped and distributed plasticity element models. In order to appraise the reliability and feasibility of each alternative, the programs capabilities and the amount of labour and time required for modelling and performing the analyses are also discussed. The results obtained show the difficulties that may be met, not only in performing nonlinear analyses, but also on their dependency on both the chosen nonlinear structural models and the adopted computer programs. It is then suggested that these procedures should only be used by experienced designers, provided that they are aware of these difficulties and with a critical stance towards the result of the analyses.

• 방송공학회논문지
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• 제13권4호
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• pp.463-478
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• 2008

분산중계 방식은 기존 중계기를 이용하는 MFN(Multiple Frequency Network)과 OCR(On Channel Repeater)을 이용한 SFN(Single Frequency Network)에 비해 기존의 송출시설을 최대한 활용할 수 있고, 짧은 시간에 구축이 가능하여 비용이 효율적이며, 주파수 이용 효율을 높일 수 있는 방식이다. 본 필드 테스트는 이러한 분산중계 방식의 성능을 검증하고자 서울 서북부 지역을 중심으로 3세대, 5세대 그리고 6세대 수신기를 이용하여 총 30개 지점에 대하여 수신 전계강도와 노이즈마진 및 수신가능각을 측정하였고, 수신화질의 주관적 평가를 수행하였다. 필드 테스트를 수행한 결과 모든 조건의 수신기에서 수신 성능의 향상을 보였다. 각 수신기별 특성을 볼 때 3세대 수신기에 비해 5세대 수신기 및 6세대 수상기는 수신율의 향상뿐만 아니라 수신가능각도 증가되어 분산중계망의 가능성을 알 수 있었다.

• 항공우주산업기술동향
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• 제9권1호
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• pp.64-76
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• 2011

자동차와 항공기가 결합된 신개념 운송수단인 미래형 개인용 항공기의 개발 현황을 살펴보고, 이러한 개인용 항공기의 개념을 분석하여 향후 기술 개발시 필요한 요구사항을 정리하였다. 최근 들어 미래형 개인용 항공기의 차세대 운송수단으로서의 그 가능성을 인지하여 미국을 중심으로 정부, 민간회사, 학계에서 미래형 개인용 항공기와 관련된 다양한 연구를 수행하고 있다. 본 논문에서는 미래형 개인용 항공기의 개발 프로그램인 AGATE, PAVE, SATS 및 NGATS 등을 먼저 알아보고, 현재 상용화가 진행 중인 Terrafugia사의 Transition과 Moller International사의 M400 Skycar의 개발 현황, 기체의 특징 및 응용 기술을 분석하였다. 이를 바탕으로 추후 미래형 개인용 항공기를 개발시 필요한 핵심기술을 제시한다.

• Nuclear Engineering and Technology
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• 제40권1호
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• pp.49-68
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• 2008

The purpose of this paper is to extensively review the condition monitoring (CM) techniques using empirical models in an effort to reduce or eliminate unexpected downtimes in general industry, and to illustrate the feasibility of applying them to the nuclear industry. CM provides on-time warnings of system states to enable the optimal scheduling of maintenance and, ultimately, plant uptime is maximized. Currently, most maintenance processes tend to be either reactive, or part of scheduled, or preventive maintenance. Such maintenance is being increasingly reported as a poor practice for two reasons: first, the component does not necessarily require maintenance, thus the maintenance cost is wasted, and secondly, failure catalysts are introduced into properly working components, which is worse. This paper first summarizes the technical aspects of CM including state estimation and state monitoring. The mathematical background of CM is mature enough even for commercial use in the nuclear industry. Considering the current computational capabilities of CM, its application is not limited by technical difficulties, but by a lack of desire on the part of industry to implement it. For practical applications in the nuclear industry, it may be more important to clarify and quantify the negative impact of unexpected outcomes or failures in CM than it is to investigate its advantages. In other words, while issues regarding accuracy have been targeted to date, the concerns regarding robustness should now be concentrated on. Standardizing the anticipated failures and the possibly harsh operating conditions, and then evaluating the impact of the proposed CM under those conditions may be necessary. In order to make the CM techniques practical for the nuclear industry in the future, it is recommended that a prototype CM system be applied to a secondary system in which most of the components are non-safety grade. Recently, many activities to enhance the safety and efficiency of the secondary system have been encouraged. With the application of CM to nuclear power plants, it is expected to increase profit while addressing safety and economic issues.

• 해양환경안전학회지
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• 제28권2호
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• pp.361-369
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• 2022

강화되는 환경규제에 대응하기 위해서 세계 각국이 수소 경제로의 전환을 본격화하고 있으며, 이에 중장기적으로 수소의 국가간 물동량도 증가할 것으로 예상된다. 국가간 수소의 거래는 수출국의 신재생 에너지 자원과 수입국의 수소 사용 형태, 기술 성숙도 등을 고려하여 암모니아, 액화수소, LOHC 등의 형태로 이루어질 것이나, 어느 한 가지 형태로만 거래되지는 않을 것이다. 액화수소 대비 암모니아와 LOHC의 해상운송은 상대적으로 성숙한 기술임에 본 글에서는 향후 액화수소 운반선 개발을 위하여 필요한 세부 기술들의 식별 및 다양한 기술적 대안들을 통해 가능한 설계안을 확보하면서, 그에 따른 기술적 타당성을 분석하였다.