• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.201-206
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• 2020

Diversification of project delivery methods (PDM) under ever-changing construction business environment has significantly changed the role of project participants. Active efforts to effectively sharing the roles and responsibilities have been observed in the project management offices (PMOs) among owner/operator organizations as well as engineering, procurement, construction and maintenance (EPCM) firms. In order for being effective in a holistic way throughout the project life-cycle, a PMO needs to have 'adequate management skills' as well as 'essential technical capabilities' in cooperating with many different participants. One of the well-known examples of the PMO's tool to support these skills and capabilities is the effective 'work packaging (WP)' that serves as a common basis integrating all relevant information in a structured manner. In an attempt to enhance the construction productivity, the concept of 'advanced work packing (AWP)' has been introduced by Construction Industry Institute (CII). The AWP enables productivity to be improved by early planning of construction packages in the design phase "with the end in mind". The purpose of this study is to identify and evaluate the 'variables' of advanced work packing (AWP) for life-cycle information integration. Firstly, an extended concept of advanced WP based on the CII AWP was defined in order to comprehend many different issues of business functions (e.g. cost, schedule, quality, etc.). A structured list of major components and variables of AWP were then identified and examined for practical viability with real-world examples. Strategic fits and managerial effectiveness were stressed throughout the analyses. Findings, implications and lessons learned are briefly discussed as well.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제37권4호
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• pp.653-674
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• 2023

수학과 교육과정에서 수학 문제해결력 신장, 수학 문제만들기 등이 꾸준히 강조되고 있다. 본 연구에서는 Brown & Walter가 제안한 what-if-not 방법과는 다른 방향의 문제만들기 방법을 연구하였다. 여기서 다루는 문제만들기 방법에서는 출발점 문제의 문제해결 과정을 분석하여 그 구성 요소들을 변화시키며, 얻어진 변화를 바탕으로 문제해결 과정을 역으로 거슬러 올라가면서 새로운 문제, 즉 출발점 문제를 변형시킨 문제를 만들었다. 이러한 순서로 문제를 만들면, 문제해결 과정으로부터 새로운 변형된 문제가 유도될 수 있다. 즉, 문제해결 과정이 문제에 선행하게 되며, 본 연구에서는 이러한 문제만들기 방법을 연역적 문제만들기라고 명명하였다. 특히, 연역적 문제만들기의 다양한 사례들, 특징들을 구체적으로 제시하였으며, 치환을 이용하여 로그가 포함된 방정식으로부터 지수, 무리식, 삼각함수가 포함된 방정식 등을 만드는 과정을 소개하였다. 연역적 문제만들기는 문제해결의 반성 단계에서 문제해결 결과를 검증하고 확장하는 활동과 관련될 수 있으며, 수학 교사가 개념 정착, 복습 등과 같은 교수학적 목적에 따라 기존 문제를 변형시킬 때도 활용할 수 있을 것으로 기대된다.

• 한국산업융합학회 논문집
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• 제26권5호
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• pp.953-965
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• 2023

The stratospheric drones are developed to perform missions such as weather observation, communication relay, surveillance, and reconnaissance at 18km to 20km, where climate change is minimal and there is no worry about a collision with aircraft. It uses solar panels for daytime flights and energy stored in batteries for night flights, providing many advantages over existing satellites. The electrical and power systems essential for stratospheric drone flight must ensure reliability, efficiency, and lightness by selecting the optimal circuit topology. Therefore, it is necessary to analyze the circuit topology of various types of multi-level inverters with high redundancy that can ensure the reliability and efficiency of the motor driving power required for stable long-term flight of stratospheric drones. By quantifying the switch element voltage drop and the number and weight of inverter components for each topology, we evaluate efficiency and lightness and propose the most suitable circuit topology for stratospheric drones.

• Journal of Dairy Science and Biotechnology
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• 제41권4호
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• pp.203-210
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• 2023

Bacterial contamination negatively affects the quality, functionality, and safety of dairy products. Adherent populations of bacteria, referred to as biofilms, grow on the surfaces of dairy processing equipment and are the primary cause of dairy contamination. In addition, microorganisms present in the farm environment and dairy factory can contaminate the Clear-In-Place (CIP) line through raw milk transport pipes; therefore, exhaustive management is required. In dairy manufacturing facilities, biofilm formation is controlled using CIP systems that primarily require sodium hydroxide and nitric acid. However, the leakage or incomplete removal of these potently active compounds can be harmful to humans. In the present study, we compared the eradication of Escherichia coli and other bacteria using commercially available combinations of sodium hypochlorite (NaClO) and citric acid, which are recognized by the Korean Ministry of Food and Drug Safety (MFDS) as food disinfectants. When considered in the CIP system of the field manufacturing process, E. coli was not detected (compared to detection before treatment), and other bacteria were detected at 0-32 culture-forming units (CFU)/cm². The residual amount of chlorine ions after CIP treatment was similar to that in tap water, and there was no significant difference in the overall components of the fermented dairy products. Therefore, the NaClO/citric acid CIP system can be safely applied in dairy manufacturing processes.

• 공업화학
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• 제34권5호
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• pp.479-487
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• 2023

구리(Cu)는 저렴한 비용으로 용이하게 도입이 가능하여 다양한 소재 표면에 살균 코팅제로 쓰이고 있다. 자연적 산화 반응이 구리의 효능을 손상시키지 않아 장기간 노출 조건에서도 항균 성능을 유지할 수 있다. 더 나아가 구리 화합물은 그람 음성균 및 그람 양성균 뿐만 아니라, 병원성 효모, 외피 보유 및 외피 미보유 타입의 바이러스에 대해 모두 폭넓은 살균 효과를 보인다. 구리 코팅 표면의 접촉 살균은 구리의 침투로 단백질 변성을 일으키고 세포막 손상으로 뉴클레오티드 및 세포질 등의 내용물이 용출되게 한다. 또한 구리 산화환원 활성에 의한 활성 산소종 생성으로 효소작용을 억제하고 DNA를 파괴하여 세포를 영구적으로 손상시킨다. 구리는 안정한 금속 성질 때문에 나노입자, 이온, 복합물, 합금 등의 여러 형태로 쓰이고 있으며 코팅 방법이 다양하다. 본 총설에서는 구리 이온과 구리 산화물의 대표적인 표면 도입 방법을 살펴보고 구리 산화수에 따른 항균·항바이러스 특성을 다루고자 한다.

• 한국재료학회지
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• 제33권10호
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• pp.377-384
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• 2023

Exploring earth-abundant, highly effective and stable electrocatalysts for electrochemical water splitting is urgent and essential to the development of hydrogen (H₂) energy technology. Iron-cobalt layered double hydroxide (FeCo-LDH) has been widely used as an electrocatalystfor OER due to its facile synthesis, tunable components, and low cost. However, LDH synthesized by the traditional hydrothermal method tends to easily agglomerate, resulting in an unstable structure that can change or dissolve in an alkaline solution. Therefore, studying the real active phase is highly significant in the design of electrochemical electrode materials. Here, metal-organic frameworks (MOFs) are used as template precursors to derive FeCo-LDH from different iron sources. Iron salts with different anions have a significant impact on the morphology and charge transfer properties of the resulting materials. FeCo-LDH synthesized from iron sulfate solution (FeCo-LDH-SO₄) exhibits a hybrid structure of nanosheets and nanowires, quite different from other electrocatalysts that were synthesized from iron chloride and iron nitrate solutions. The final FeCo-LDH-SO₄ had an overpotential of 247 mV with a low Tafel-slope of 60.6 mV dec^-1 at a current density of 10 mA cm^-2 and delivered a long-term stability of 40 h for the OER. This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

• 한국식생활문화학회지
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• 제38권6호
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• pp.434-441
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• 2023

This study investigated quality characteristics and antioxidant activity of beetroots after blanching. Beetroots were blanched in distilled water, 2% NaCl water, and 2% citric acid water at 100℃ for 3 minutes (the blanched group). The moisture content was highest in the control (CON) at 91.30% (p<0.05), and cooking loss was lowest in the water-blanched beetroot (BW) at 5.39% (p<0.01). Chromaticity decreased after blanching compared to CON (p<0.001). Total polyphenol contents (TPC) and total flavonoid contents (TFC) decreased after blanching, and as a result of comparing the True retention (TR) of the blanching treatment group, BW had the highest with TPC TR 91.22% and TFC TR 70.51%. DPPH and ABTS+radical scavenging activities were highest in the CON, and in the blanching group BW was highest scavenging activity. The total number of microorganisms in the CON group was 2.97 log CFU/g, whereas no microorganisms were detected in the blanched groups. Therefore, this study, blanching in water without additives is the most appropriate method for preserving physiologically active substances and nutrients in beetroots and inhibiting microbial growth.

• 산업과 과학
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• 제2권4호
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• pp.36-43
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• 2023

넓은 맥락에서, 자생식물은 인공적인 보호나 재배 없이 특정 지역에서 자연적으로 발생하고 번성하는 식물로, 그들이 생존을 위해 가장 적합한 환경에서 자랍니다. 이러한 식물들은 유전자 자원, 번식 재료 및 생명공학 자산으로서 상당한 잠재력을 갖추고 있으며, 식용, 의약, 그리고 장식용 등 다양한 분야에서 발전의 가능성이 있습니다. 자생식물의 가능성을 활용하기 위해, 우리의 목표는 자생식물의 활용, 효과, 유효성분, 추출 방법 등에 초점을 맞춘 국내 특허 분석을 통해 가치 있는 정보를 제공하는 것이었습니다. 한국 산림청에서 등록된 국가 표준 식물 목록을 활용하여, 자생식물과 자생식물 식물 종자 사용과 관련된 988건의 특허에 대한 유효한 데이터를 확보했습니다. 이 분석은 특허의 종합적 검토를 통해 연구 패턴, 주요 기술 수준 및 신흥 트렌드를 밝혀내는 목적이 있었습니다. 결과적으로, 특허 분석을 통해 연구 트렌드와 현재 기술 수준을 확인하고, 자생식물을 활용한 향후 특허 출원을 위한 정보를 제공하기 위한 것입니다.

• 한국가스학회지
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• 제27권4호
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• pp.110-115
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• 2023

부생가스 발생 및 이용현황보고서(2015)에 따르면 철강 사업에서 나오는 부생가스는 국내 연간 8,000만톤으로 추정된다. 이를 정제할 경우 다량의 수소 생산이 가능하여 수소 정제시설과 관련해 활발한 연구 개발이 진행 중이다. 본 연구에서는 부생가스 기반 수소 정제시설의 구성요소를 분석하고 위험요인을 조사하여 정량적 위험성 평가(QRA)를 실시하였다. 위험도 분석 결과는 허용 가능 수준으로 도출되었으며 수소의 위험성을 고려한 시설물의 안전성 향상을 위한 기초자료로 활용할 예정이다.

• Journal of Ginseng Research
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• 제48권1호
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• pp.1-11
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• 2024

Fresh ginseng is prone to spoilage due to its high moisture content. For long-term storage, most fresh ginsengs are dried to white ginseng (WG) or steamed for hours at high temperature/pressure and dried to form Korean Red ginseng (KRG). They are further processed for ginseng products when subjected to hot water extraction/concentration under pressure. These WG or KRG preparation processes affect ginsenoside compositions and also other ginseng components, probably during treatments like steaming and drying, to form diverse bioactive phospholipids. It is known that ginseng contains high amounts of gintonin lysophosphatidic acids (LPAs). LPAs are simple lipid-derived growth factors in animals and humans and act as exogenous ligands of six GTP-binding-protein coupled LPA receptor subtypes. LPAs play diverse roles ranging from brain development to hair growth in animals and humans. LPA-mediated signaling pathways involve various GTP-binding proteins to regulate downstream pathways like [Ca²⁺]_i transient induction. Recent studies have shown that gintonin exhibits anti-Alzheimer's disease and antiarthritis effects in vitro and in vivo mediated by gintonin LPAs, the active ingredients of gintonin, a ginseng-derived neurotrophin. However, little is known about how gintonin LPAs are formed in high amounts in ginseng compared to other herbs. This review introduces atypical or non-enzymatic pathways under the conversion of ginseng phospholipids into gintonin LPAs during steaming and extraction/concentration processes, which exert beneficial effects against degenerative diseases, including Alzheimer's disease and arthritis in animals and humans via LPA receptors.