• Environmental Engineering Research
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• 제25권1호
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• pp.88-95
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• 2020

An investigation of rare metals recovery from LiNi_xCo_yMn_zO₂ cathode material of the end-of-life lithium-ion batteries is presented. To determine the influence of reductant on the leach process, the cathode material (containing Li 7.6%, Co 20.4%, Mn 19.4%, and Ni 19.3%) was leached in H₂SO₄ solutions either with or without H₂O₂. The optimal process parameters with respect to acid concentration, addition dosage of H₂O₂, temperature, and the leaching time were found to be 2.0 M H₂SO₄, 4 vol.% H₂O₂, 70℃, and 150 min, respectively. The yield of metal values in the leach liquor was > 99%. The leach liquor was subsequently treated by precipitation techniques to recover nickel as Ni(C₄H₇N₂O₂)₂ and lithium as Li₂CO₃ with stoichiometric ratios of 2:1 and 1.2:1 of dimethylglyoxime:Ni and Na₂CO₃:Li, respectively. Cobalt was recovered by solvent extraction following a 3-stage process using Na-Cyanex 272 at pH_eq ~5.0 with an organic-to-aqueous phase ratio (O/A) of 2/3. The loaded organic phase was stripped with 2.0 M H₂SO₄ at an O/A ratio of 8/1 to yield a solution of 114 g/L CoSO₄; finally recovered CoSO₄.xH₂O by crystallization. The process economics were analyzed and found to be viable with a margin of $476 per ton of the cathode material.

• Journal of Hospice and Palliative Care
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• 제22권1호
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• pp.1-7
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• 2019

한국에서 호스피스의 기원은 11세기 초, 고려시대의 동서대비원(東西大悲院)에서 그 유래를 찾을 수 있다. 한국에 호스피스가 도입된 이후, 50여년이 흘렀고, 초기에는 종교적 배경과 민간차원의 활동이 더디게 발전해왔으나, 1990년대에 각 종교단체가 구성되고 학회가 출범한 이후, 2000년대 초기부터 정부의 개입으로 제도화가 진행되면서 본격적인 성장기를 맞게 되었다. 비록 말기암환자와 그 가족들의 고통이 경감되고 삶의 질과 서비스의 질은 향상되었으나, 안정적인 재정기반을 보장할 수 있는 현실적인 보상체계는 마련되지 못했었다. 그러나, 2015년에 호스피스 완화의료 서비스에 대한 국민건강보험 급여수가가 인정되었고, 2016년에 "호스피스 완화의료 및 임종과정에 있는 환자의 연명의료결정에 관한 법률"이 제정되어 말기환자의 무의미한 연명치료를 거부할 수 있게 되었으며, 호스피스 완화의료 서비스의 대상 질환이 확대되면서 서비스제공자들에게는 더 많은 도전과 과제들이 남아있다.

• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.622-629
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• 2020

The performance and cost of electric vehicles (EVs) are much influenced by the performance and service life of the Li-ion battery system. In particular, the cell performance and reliability of Li-ion battery packs are highly dependent on their operating temperature. Therefore, a novel battery thermal management is crucial for Li-ion batteries owing to heat dissipation effects on their performance. Among various types of battery thermal management systems (BTMS'), the phase change material (PCM) based BTMS is considered to be a promising cooling system in terms of guaranteeing the performance and reliability of Li-ion batteries. This work is mainly concerned with the basic research on PCM based BTMS. In this paper, a basic experimental study on PCM based battery cooling system was performed. The main purpose of the present study is to present a comparison of two PCM-based cooling systems (n-Eicosane and n-Docosane) of the unit 18650 battery module. To this end, the simplified PCM-based Li-ion battery module with two 18650 batteries was designed and fabricated. The thermal behavior (such as temperature rise of the battery pack) with various discharge rates (c-rate) was mainly investigated and compared for two types of battery systems employing PCM-based cooling. It is considered that the results obtained from this study provide good fundamental data on screening the appropriate PCMs for future research on PCM based BTMS for EV applications.

• FOCUS: LIFE SCIENCE
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• 제1호
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• pp.1.1-1.4
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• 2024

This article provides comprehensive guidance on the maintenance, cleaning, regeneration, and storage of silica-based HPLC (High-Performance Liquid Chromatography) columns. The general considerations emphasize the importance of using in-line filters and guard cartridges to protect columns from blockage and irreversible sample adsorption. While these measures help, contamination by strongly adsorbed sample components can still occur over time, leading to an increase in back pressure, loss of efficiency, and other issues. To maximize column lifetime, especially with UHPLC (Ultra-High Performance Liquid Chromatography) columns, it is advisable to use ultra-pure solvents, freshly prepared aqueous mobile phases, and to filter all samples, standards, and mobile phases. Additionally, an in-line filter system and sample clean-up on dirty samples are recommended. However, in cases of irreversible compound adsorption or column voiding, regeneration may not be possible. The document also provides specific recommendations for column cleaning procedures, including the flushing procedures for various types of columns such as reversed phase, unbonded silica, bonded normal phase, anion exchange, cation exchange, and size exclusion columns for proteins. The flushing procedures involve using specific solvents in a series to clean and regenerate the columns. It is emphasized that the flow rate during flushing should not exceed the specified limit for the particular column, and the last solvent used should be compatible with the mobile phase. Furthermore, the article outlines the storage conditions for silica based HPLC columns, highlighting the impact of storage conditions on the column's lifetime. It is recommended to flush all buffers, salts, and ion-pairing reagents from the column before storage. The storage solvent should ideally match the one used in the initial column test chromatogram provided by the manufacturer, and column end plugs should be fitted to prevent solvent evaporation and drying out of the packing bed.

• 토지주택연구
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• 제10권3호
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• pp.43-55
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• 2019

본 연구에서는 수도권의 새로운 신도시 건설이 추진됨에 따라 향후 신도시 계획시 고려해야 할 지표와 개발방향에 대하여 고찰하였다. 이를 위해 분야별 전문가들을 대상으로 조사한 설문자료를 빈도분석과 분산분석기법을 이용해 분석한 결과, 다음과 같은 시사점들이 도출되었다. 첫째, 기존 1기 및 2기 신도시에 대해 계획지표들의 평가결과, 시민참여와 정보공유, 스마트기술과 서비스, 사회문화적 다양성과 포용성에서 부정적 평가가 많았다. 또한 3기 신도시에 대해 전문가들은 교통의 접근성과 편리성, 환경적 쾌적성, 주거의 질과 서비스 등 도시의 기본이 되는 요소인 교통, 환경, 주거의 중요성을 가장 높게 인식하고 있으며, 경관/디자인의 우수성, 일자리 등 자족성, 사회·문화적 다양성과 포용성 등도 중요한 지표로 꼽았다. 둘째, 전문가들의 인식과 평가가 성별, 연령, 직업, 전문분야 등 개인특성에 따라 차이가 있는지를 알아본 결과, 1기와 2기 신도시는 전문가 집단의 '성별'에서만 유의적 차이를 보였으며, 3기 신도시는 '성별'과 '전문분야'에서 유의적 차이가 있었다. 셋째, 향후 3기 신도시 개발계획 수립시 인구구조변화, 산업과 일자리, 삶의 질과 다양성, 환경 및 기후변화, 사회 및 주거복지 등을 중요하게 고려해야 한다고 보았다. 토지이용계획에서는 공원녹지 및 자족용지 확대를 중요하게 생각하였고 3기 신도시의 도시형태로 친환경 생태도시를 1순위로 꼽았으며, 중요한 생활인프라로 대중교통시설, 공원녹지, 교육시설을 매우 중요하게 보았다.

• 한국가정과교육학회지
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• 제13권1호
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• pp.39-53
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• 2001

The purpose of this study is to develop lesson plan and to evaluate its application for the chapter of 'family life and housing'in the class of Home Economics in the third grade of middle school through the application of the Universal Design. This study has been done in three phases : analysis. development. and evaluation phase. The results of this study were as follows : First. in the development of the concept of the Universal Design. the objective of learning aimed to build the housing and utilities for all family members. Moreover. the various learning materials such as computer program. video materials. and worksheets of the group work were utilized to enhance the effectiveness of the lesson plan. Second. the evaluation of the students was examined through the assessment of the concept of the design. and the degree of class participation of student at the end of class. The LT cooperative learning as an instructional method was perceived to be appropriate and the participation of the cooperative work was also enhanced. The use of the computer programs. and video tapes was considered to be useful. Third. the response of the teachers was found to be both positive and negative. Teachers'positive reactions indicated that the use of the Universal Design facilitated student's participation in class stimulating their motivations and creative ideas not only in the classroom but also in the real life as for the negative reactions. teachers perceived understanding of the concept of the Universal Design. the activities of the students and class hours were relatively shout. These should be added to by the further study with the teachers endeavor.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1181-1187
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• 2012

항공기 착륙장치의 피로설계에는 안전수명 방법이 적용된다. 즉, 균열이나 유해한 변형과 같은 구조적 결함이 항공기 운용수명 기간을 모사하는 피로 하중 스펙트럼 조건에서 발생하지 않아야 한다. 일반적으로 항공기 착륙장치는 고주기 피로 환경에 노출되므로, 설계 단계에서 착륙장치의 피로 수명은 응력 기반의 해석을 통해 예측한다. 이를 위해 재료의 분산(Scatter) 및 표면처리 특성 등을 고려한 설계 S-N 선도를 구성하여 해석에 사용한다. 시험평가 단계에서는 실물 착륙장치에 대한 피로시험을 통해 피로설계 요구조건 충족 여부를 최종 검증한다. 본 논문에서는 항공기 착륙장치의 피로수명 해석 및 시험절차를 실제 적용 사례를 통해 제시하였다.

• 한국초지조사료학회지
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• 제41권3호
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• pp.183-188
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• 2021

The increase in temperature due to climate warming is predicted to affect crop yields in the future. Until now, various types of OTC (open top chamber) that simulate the future climate condition have been developed and used to study the effect of temperature increase due to global warming on maize growth. However, in most OTCs, high equipment and maintenance costs were required to artificially increase the temperature. This study was carried to develop a cost-effective and simple OTC suitable for climate warming experiments for forage maize. Three octagonal OTCs with a height of 3.5 m × a diameter of 4.08 m and a partially covered top were constructed. The lower part of OTC covered film was opened at a height of 26 cm (OTC-26), 12 cm (OTC-12) from the ground surface, or not opened (0 cm, OTC-0). Mean air temperatures during the daytime on a sunny day in OTC-0, OTC-12 and OTC-26 increased to 3.23℃, 1.33℃, and 0.89℃, respectively, compared to the ambient control plot. For a pilot test, forage maize, 'Gwangpyeongok' was grown at OTCs and ambient control plots. As a result, in the late maize vegetative growth phase (July 30), the plant height was increased more than 45% higher than the ambient control plot in all OTC plots, and the stem diameter also increased in all OTC plots. These results indicate that it is possible to set the temperature inside the OTC by adjusting the opening height of the lower end of the OTC, and it can be applied to study the response of forage maize to elevated temperature. An OTC, with its advantages of energy free, low maintenance cost, and simple temperature setting, will be helpful in studying maize growth responsiveness to climate warming in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2188-2208
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• 2023

Quality of Service (QoS) is a critical feature of Wireless Sensor Networks (WSNs) with routing algorithms. Data packets are moved between cluster heads with QoS using a number of energy-efficient routing techniques. However, sustaining high scalability while increasing the life of a WSN's networks scenario remains a challenging task. Thus, this research aims to develop an energy-balancing component that ensures equal energy consumption for all network sensors while offering flexible routing without congestion, even at peak hours. This research work proposes a Gravitational Blackhole Search Optimised splay tree routing framework. Based on the splay tree topology, the routing procedure is carried out by the suggested method using three distinct steps. Initially, the proposed GBSO decides the optimal route at initiation phases by choosing the root node with optimum energy in the splay tree. In the selection stage, the steps for energy update and trust update are completed by evaluating a novel reliance function utilising the Parent Reliance (PR) and Grand Parent Reliance (GPR). Finally, in the routing phase, using the fitness measure and the minimal distance, the GBSO algorithm determines the best route for data broadcast. The model results demonstrated the efficacy of the suggested technique with 99.52% packet delivery ratio, a minimum delay of 0.19 s, and a network lifetime of 1750 rounds with 200 nodes. Also, the comparative analysis ensured that the suggested algorithm surpasses the effectiveness of the existing algorithm in all aspects and guaranteed end-to-end delivery of packets.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1414-1418
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• 2009

International construction projects typically manifest difficult, complex, and varied types of risk exposures; because of this, there is a need for accurate evaluation of risk-integrated performances during the timeframe of project execution. Given the financial crisis currently affecting the world economy recession, risk management has become a more crucial part for the success of international project management. However, the majority of risk management approaches, particularly for overseas projects, are focused primarily on simple forms of checklists, formalization of risk variables affecting project performance for a specific phase, or more complicated computational methods that restricting practical utilization in real-world projects; moreover, these methods lack the conceptual basis to broadly visualize the level of risk over all phases of a project. This study suggests an efficient, yet simple risk-integrated total index to successfully assess the risk levels of overseas construction projects. To this end, this paper first investigates the life cycles and key processes of decision-making for a given project and then derives formulas to represent the total risk index (TRI) along the key decision-making processes. In addition, the study examines the relationships between TRI and performance levels based on the analysis of 126 real-world project samples. Validations using the proposed TRI showed a high correlation to project performance, signifying the usefulness of the proposed approach for construction firms when investigating the level of risks and key areas for management focus.