• 자원리싸이클링
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• 제28권4호
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• pp.3-14
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• 2019

납은 현대산업에서 범용적으로 사용되는 비철금속이다. 전세계의 납 생산량은 1970년대의 약 500만 톤에서 점차 증가하여 2010년대에는 1,100만 톤까지 이르렀다. 특히 납은 품질의 저하없이 100 % 리사이클링할 수 있는 금속으로, 납 스크랩을 리사이클링하면 1차 지금 생산과 비교하여 에너지 및 환경부하를 현저하게 저감할 수 있다. 이러한 이유로 전세계 납 사용량의 약 60 %는 리사이클링으로부터 공급되고 있다. 주로 납축전지인 납 스크랩은 1차 제련소나 2차제련소에서 정련하고 있다. 대부분의 2차 제련은 용광로와 같은 샤프트로, 회전로, 그리고 반사로에서 이루어 지고 있다. 2차 제련에서 생산된 조연은 잉곳으로 주조하거나 케틀로에서 재용해하여 정제를 하지만, 용융상태의 조연에서 곧바로 정련을 하기도 한다. 본 연구에서는 납의 1차지금 생산 및 리사이클링 공정에 대해 고찰하였다.

• 한국문헌정보학회지
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• 제53권2호
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• pp.49-68
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• 2019

초 중등학교에 있어서 교육과정은 교육의 핵심이다. 교육과정은 교육의 목적과 목표, 교육내용, 교육자료 및 교수-학습방법을 규정한 종합적인 교육계획이다. 우리나라를 비롯한 많은 국가에서는 초 중등학교 교육을 위한 국가수준의 교육과정을 마련하고 있다. 우리나라의 경우에는 국가수준의 교육과정은 10차례에 걸쳐 개정한 바 있으며, 현재는 '2015 개정 교육과정'을 적용하고 있다. 한편, 한국도서관협회에서는 2007년에 초 중등학교의 정보활용교육을 위해서 '도서관과 정보생활' 교육과정을 개발하였다. 그러나 이 교육과정은 국가수준의 교육과정인 '2007 개정 교육과정'에 근거하고 있어서 현행 '2015 개정 교육과정'의 구조와 내용체계와는 차이가 있다. '도서관과 정보생활' 교육과정은 '2015 개정 교육과정'의 구조와 내용체계에 맞추어 개정할 필요가 있다. 이에 본 연구에서는 '2015 개정 교육과정'과 '도서관과 정보생활' 교육과정을 비교, 분석한 후에 '도서관과 정보생활' 교육육과정의 개정 방향을 제안하였다.

• 한국안전학회지
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• 제39권2호
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• pp.38-43
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• 2024

Recently, with the expanding market for electronic devices and electric vehicles, secondary battery usage has been on the rise. Lithium-ion batteries are particularly popular due to their fast charging times and lightweight nature compared to other types of batteries. A secondary battery consists of four components: anode, cathode, electrolyte, and separator. Generally, the positive and negative electrode materials of secondary batteries are composed of an active material, a binder, and a conductive material. Acetylene Black (AB) is utilized to enhance conductivity between active material particles or metal dust collectors, preventing the binder from acting as an insulator. However, when recycling waste batteries that have been subject to high usage, there is a risk of fire and explosion accidents, as accurately identifying the characteristics of Acetylene Black dust proves to be challenging. In this study, the lower explosion limit for Acetylene Black dust with an average particle size of 0.042 ㎛ was determined to be 153.64 mg/L using a Hartmann-type dust explosion device. Notably, the dust did not explode at values below 168 mg, rendering the lower explosion limit calculation unfeasible. Analysis of explosion delay times with varying electrode gaps revealed the shortest delay time at 3 mm, with a noticeable increase in delay times for gaps of 4 mm or greater. The findings offer fundamental data for fire and explosion prevention measures in Acetylene Black waste recycling processes via a predictive model for lower explosion limits and ignition delay time.

• Journal of Trauma and Injury
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• 제19권2호
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• pp.183-187
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• 2006

An increase has been see in fall injuries at construction sites and in penetrating injuries by iron bars or pipes associated with the fall. In particular, a thoraco-abdominal penetrating injury had the worse prognosis, and multiple organ injury occurred because of blunt trauma associated with fall. Iron bars were the most common penetrating materials, and pipe penetrating injuries were uncommon. However, because the diameter of the pipes were large than those of the bars, penetrating injuries associated with pipes were more often fatal. A secondary thoraco-abdominal injury worsened the prognosis. We reported a case of a 33-year-old man with a thoraco-abdominal trauma secondary to a penetrating injury with a scaffolding pipe following a fall.

• 전기화학회지
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• 제16권1호
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• pp.9-18
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• 2013

Zinc air 전지의 구성요소와 전지의 특징을 설명하였다. 리튬 이온 전지에 비해 월등히 높은 에너지 밀도를 가지고 있지만, 충전의 비가역성으로 인한 낮은 용량 유지 특성 때문에 zinc air 이차전지는 아직 상용화되지 못하였다. Zinc air 전지는 충방전에 관여하는 반응들의 속도가 느려서 그 반응들의 속도를 촉진해야 하는 특징이 있는가 하면 동시에 부식과 수소발생 반응의 속도는 오히려 느리게 해야 하는 까다로운 조건을 만족해야 한다. 기존의 전지들과 비교하면, 기초연구뿐 아니라, 전지의 기계적구조, 부식, 복합소재적인 요소의 적용이 더욱 필요한 연구분야라고 하겠다. 출력개선과 부식방지 그리고 공기의 공급에 대비한 물의 증발의 억제 등은 상충하는 성질을 동시에 만족해야 하는 복합소재의 특성이다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권6호
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• pp.3483-3489
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• 2013

Background: To identify the prevalence of different stages of smoking and differences in associated risk factors. Materials and Methods: Thos longitudinal study started in February 2011 and the subjects were 2552 form one students aged between twelve to thirteen years of from 15 government secondary schools of Kinta, Perak. Data on demographic, parental, school and peer factors were collected using a self-administered questionnaire. We examined the effects of peer, school and parental factors on the five stages of smoking; never smokers, susceptible never smokers, experimenters, current smokers and ex-smokers, at baseline. Results: In the sample, 19.3% were susceptible never smokers, 5.5% were current smokers 6% were experimenters and 3.1% were ex-smokers. Gender, ethnicity, best friends' smoking status, high peer pressure, higher number of relatives who smoked and parental monitoring were found to be associated with smoking stages. Presence of parent-teen conflict was only associated with susceptible never smokers and experimenters whereas absence of home discussion on smoking hazards was associated with susceptible never smokers and current smokers. Conclusions: We identified variations in the factors associated with the different stages of smoking. Our results highlight that anti-smoking strategies should be tailored according to the different smoking stages.

• 한국의학물리학회지:의학물리
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• 제31권2호
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• pp.29-34
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• 2020

Purpose: The interaction of various substances inserted into the human body and radiation can confirm the radiation enhancement effect. A Leksell frame inserted into the human body for gamma knife treatment will cause not only pain and inconvenience to the patient, but also additional exposure to the patient's normal tissues. In this study, we attempt to confirm the additional exposure caused by the interaction of the Leksell frame and thermoplastic mask, and ⁶⁰Co used for gamma knife treatment. Methods: A ⁶⁰Co energy of 1.17, 1.33 MeV is applied using Monte Carlo simulation, and fixation screws and thermoplastic mask are fabricated using aluminum and titanium alloy, and Carbon compounds. Results: Results show a dose enhancement of up to 396.27% higher compared with that without a Leksell frame and up to 391.25% in thermoplastic mask. Conclusions: Hence, appropriate treatment methods and materials must be used to reduce additional exposure to normal tissues.

• 한국산업보건학회지
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• 제25권4호
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• pp.584-590
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• 2015

Objectives: The purpose of this study was to evaluate quartz concentrations in airborne total and respirable dusts. Materials: Respirable dust samples were collected using a 10 mm aluminum cyclone equipped with a 37 mm$5{\mu}m$ pore size PVC filter. Total dust samples were collected with a three stage cassette from three work sections at earthwork sites located in the South Chungcheong-do Province area. Results: The geometric means of quartz concentrations were $0.008mg/m^3$ and $0.004mg/m^3$ in total dust and respirable dust, respectively. The geometric means of quartz contents analyzed by FTIR were 3.74% in total dust and 3.16% in respirable dust. The geometric mean of quartz concentrations and contents in secondary blasting operations were higher than those in other operations. Conclusions: Given that secondary blasting operations had higher quartz concentrations, there is a need to reduce respirable dust, such as through wet operations.

• Natural Product Sciences
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• 제17권1호
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• pp.45-50
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• 2011

Sophisticated modern research tools for evaluation of medicinal plants are available but microscopic methods are one of the simplest and cheapest methods to establish the identity of the source materials. Pharmacognostical investigation of the dried, powdered and anatomical sections of the fruits of Trachyspermum roxburghianum (DC) Craib was carried out to determine its macro and microscopical characteristics along with its physical constants. Externally, the fruits, yellowish or greenish brown in colour are elongated, elliptical, slightly curved, prominently ridged and longitudinal. As seen in transectional views of the fruits from Trachyspermum roxburghianum, the mericarp has concave sides called commissural surfaces and a convex outer side called the dorsal surface. The mericarp has three primary ridges alternating with two secondary ridges on the dorsal side. On the commissural side, there are two primary ridges which are lateral in position and two secondary ridges in the commissural side. The seed is attached to the pericarp by a short stalk called a raphe. Circular, four-lobed calcium oxalate crystals are fairly abundant in the endosperm. Phytochemical studies revealed the presence of phenolic compounds, triterpenoids, proteins and sugars. The pharmacognostical profile of the fruits will assist in standardization for quality, purity and sample identification.

• 한국정밀공학회지
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• 제29권10호
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• pp.1137-1143
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• 2012

Creep characteristic is an important failure mechanism when evaluating engineering materials that are soft material as polymers or used as mechanical elements at high temperatures. One of the popular thermo-plastic polymers, Acrylonitrile Butadiene Styrene (ABS) which is used broadly for machine elements material, as it has excellent mechanical properties such as impact resistance, toughness and stiffness compared to other polymers, was studied for creep characteristic at different levels of stress and temperatures. From the experimental results, the creep limit of ABS at room temperature is 80 % of tensile strength which is higher than PE and lower than PC or PMMA. Also the creep limits decreased to linearly as the temperatures increased, up to $80^{\circ}C$ which is the softening temperature of Butadiene ($82^{\circ}C$). Also the secondary stage of creep among the three creep stages for different levels of stress and temperature was non-existent which occurred for many metals by strain hardening effect.