• 한국환경농학회지
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• 제31권1호
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• pp.75-95
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• 2012

BACKGROUND: Increase of heavy metals in agricultural ecosystem has become a social issue nationwide as it is related to public health. This review was performed to find out more systematic and integrated future researches on heavy metals using up to date articles published in the Korean journals related to agricultural environment. METHODS AND RESULTS: Researches on heavy metals in agricultural soils and plant uptake were categorized by the establishment of criteria, analytical methods, monitoring, management of source, characteristics and behavior in soil, plant uptake, bioavailability affecting physico -chemical properties in soil, risk assessment and soil remediation. In the early 1990s, the monitoring for heavy metals in soil has been widely performed. Accumulation of heavy metals in contaminated soil and availability to plants has also attracted interests to study the soil remediation using various physico-chemical methods. The phytoavailability and phytotoxicity of heavy metals have been mainly studied to assess the safety of agro-products using risk assessment techniques in the 2000s. CONCLUSION: Future direction of research on heavy metal in agricultural environment must be carried out by ensuring food safety and sustainability. A steady survey and proper management for polluted regions should be continued. Law and regulation must be modified systematically. Furthermore, studies should expand on mitigation of heavy metal uptake by crops and remediation of polluted fields.

• 한국지반환경공학회 논문집
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• 제14권6호
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• pp.5-11
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• 2013

국내의 소음 진동규제는 점점 더 강화되고 있어 도심지 근접시공을 위해 현재의 저소음 저진동 공법보다 더욱 환경친화적인 공법이 필요하게 되었다. 이 연구에서는 무소음 무진동 공법을 위한 스크류콘크리트말뚝공법의 특징에 대하여 설명하였으며 국내 특정 현장에서 시험시공을 실시하고 말뚝재하시험을 실시하여 시공방법에 따른 연직하중 지지능력을 연구하였다. 선행굴착방식으로 시공된 스크류콘크리트말뚝의 연직압축지지력이 선단분출형슈방식으로 시공된 스크류콘크리트말뚝의 그것보다 70% 이상 크게 나타났다.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.573-580
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• 2013

The combined effects of reactivity coefficients, along with other core nuclear characteristics, determine reactor core behavior in normal operation and accident conditions. The Power Coefficient of Reactivity (PCR) is an aggregate indicator representing the change in reactor core reactivity per unit change in reactor power. It is an integral quantity which captures the contributions of the fuel temperature, coolant void, and coolant temperature reactivity feedbacks. All nuclear reactor designs provide a balance between their inherent nuclear characteristics and the engineered reactivity control features, to ensure that changes in reactivity under all operating conditions are maintained within a safe range. The $CANDU^{(R)}$ reactor design takes advantage of its inherent nuclear characteristics, namely a small magnitude of reactivity coefficients, minimal excess reactivity, and very long prompt neutron lifetime, to mitigate the demand on the engineered systems for controlling reactivity and responding to accidents. In particular, CANDU reactors have always taken advantage of the small value of the PCR associated with their design characteristics, such that the overall design and safety characteristics of the reactor are not sensitive to the value of the PCR. For other reactor design concepts a PCR which is both large and negative is an important aspect in the design of their engineered systems for controlling reactivity. It will be demonstrated that during Loss of Regulation Control (LORC) and Large Break Loss of Coolant Accident (LBLOCA) events, the impact of variations in power coefficient, including a hypothesized larger than estimated PCR, has no safety-significance for CANDU reactor design. Since the CANDU 6 PCR is small, variations in the range of values for PCR on the performance or safety of the reactor are not significant.

• 디지털융복합연구
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• 제11권3호
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• pp.33-40
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• 2013

스마트폰, 스마트TV, 태블릿PC 등 스마트 기기의 보급으로 이러한 매체를 통해 제공되는 스마트광고가 확산되고 있다. 하지만 이러한 스마트광고도 기존 광고의 틀에 얽메여 스마트 기기의 발전만큼 빠른 광고 기술의 발전을 보여주지 못하고 있다. 이러한 관점에서 본 연구는 스마트광고의 활용 현황과 문제점 등의 분석을 통하여 스마트광고의 활성화 방안 등을 모색하고 있다. 현재 현업에서 가장 활발하게 이용되고 있는 스마트광고는 VOD광고, QR코드광고, SNS광고, 검색광고 등이다. 스마트광고의 문제점 및 개선점으로는 비합리적 효과측정 및 과금 체계, 광고의 표준화와 성공적인 수익 모델의 부재, 신뢰성 확보 문제, 전문 인력의 부족 등으로 지적되었다. 결국 스마트광고의 활성화 방안으로는 광고의 표준화와 과학적 효과측정, 다양한 형태의 광고 개발과 인력 양성, 미국의 IAB와 같은 미디어 랩 설치 등이 필요한 것으로 지적되었다.

• 융합정보논문지
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• 제10권7호
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• pp.223-231
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• 2020

노인 운전자는 기능저하로 인해 사고 위험성이 증가하지만 스스로 변화를 점검하는 자가-조절 능력 또한 발달한다. 이에 실제 노인 운전자가 운전 능력과 위험성 변화에 대응하는 특성에 대한 정보는 노인의 운전 능력 평가 현장과 연구에 의미있는 근거를 제공할 수 있다. 따라서 본 연구의 목적은 한국 노인 운전자의 운전 위험성 자각 특성을 운전 중 행동과 운전관련 기능변화의 측면에서 분석하여 노인 운전자 평가를 위한 기초 자료를 제공하는 것이다. 지역사회에 거주하는 노인 운전자 500명을 대상으로 자가-보고식 평가를 실시하고 노인 운전자의 운전 위험성 자각 징후를 분석하였다. 그 결과 다수의 노인 운전자가 시각 및 청각이 저하되거나 운전 여건 변화에 적응하는데 어려움을 느낄 때 운전 위험성을 자각하는 특성이 있음을 확인하였다. 반면, 약물 복용이나 간질, 발작, 의식손실 등 의학적 건강 상태 변화에는 둔감하게 반응하는 특성이 확인되었다. 본 연구 결과가 고령화가 가속화되는 한국의 노인 운전자 안전 관리에 기여할 수 있기를 기대한다.

• 대한간호학회지
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• 제50권1호
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• pp.116-131
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• 2020

Purpose: This study aimed to develop a smartphone overdependence prevention program for college students based on the self-determination theory (SDT) and evaluate its effectiveness. Methods: A non-equivalent control group repeated measures design was used for the study. Participants were 64 university freshmen (experimental group: 29, control group: 35). The developed program consists of eight sessions conducted twice a week. The program was designed to promote autonomy, competence, and relatedness the three elements of the basic psychological needs of self-determination theory. The participants were assessed before the program, immediately after, and 1 and 3 months after the program. Data were collected from April 23 to September 14, 2018 and analyzed by performing a Chi-square test, Fisher's exact test, independent t-test, and repeated measures ANOVA using SPSS/WIN 23.0. Results: This study showed improvement in the basic psychological needs (F=3.90, p=.010) in the experimental group compared to the control group. Specifically, competence (F=2.93, p=.035), relatedness (F=2.89, p=.045), and self-regulatory ability (F=3.11, p=.028) improved significantly. Conclusion: Study findings indicate that the smartphone overdependence prevention program based on the Self-determination theory could be an effective intervention for improving basic psychological needs and self-regulation ability. Therefore, this program could be an efficient strategy for smartphone overdependence prevention in university students.

• 대한본초학회지
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• 제35권5호
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• pp.33-39
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• 2020

Objectives : Increasing evidence supports the biological and pharmacological activities of essential oils on the central nervous system such as pain, anxiety, attention, arousal, relaxation, sedation and learning and memory. The purpose of present work is to investigate the protective effect and molecular mechanism of cypress essential oil (CEO) against scopolamine (SCO)-induced cognitive impairments in C57BL/6 mice. Methods : A series of behavior tests such as Morris water maze, passive avoidance, and fear conditioning tests were conducted to monitor learning and memory functions. Immunoblotting and RT-PCR were also performed in the hippocampal tissue to determine the underlying mechanism of CEO. Results : SCO induced cognitive impairments as assessed by decreased step-through latency in passive avoidance test, relatively low freezing time in fear conditioning test, and increased time spent to find the hidden platform in Morris water maze test. Conversely, CEO inhalation significantly reversed the SCO-induced cognitive impairments in C57BL/6 mice comparable to control levels. To elucidate the molecular mechanisms of memory enhancing effect of CEO we have examined the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus. CEO effectively elevated the protein as well as mRNA expression of BDNF via activation of cAMP response element binding protein (CREB). Conclusions : Our findings suggest that CEO inhalation effectively restored the SCO-impaired cognitive functions in C56BL/6 mice. This learning and memory enhancing effect of CEO was partly mediated by up-regulation of BDNF via activation of CREB.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.119-126
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• 2001

The potential pollution problems resulting from tanker collision necessitate the requirement for an effective structural design and the development of relevant safety regulation. During a few decades, the great effort has been made by International Maritime Organization and the Administration, etc, to reduce oil spillage from collision accidents. However there is still a need for investigation in the light of structural evaluation method for the experiments and rational analysis, and design development for an operational purpose of ships. This study is aimed at investigating a complicated structural response of bow structures of oil carriers for assessing the energy dissipation and crushing mechanics of striking vessel through a methodology of the numerical analysts for the various models and its design changes. Through this study an optimal bow construction absorbing great portion of kinetic energy in the least penetration depth prior to reach to the cargo area and an effective location of collision bulkhead are investigated. In order to obtain a rational results in this study, three stages of response analysis procedures are performed as follows; 1). 16 simplified ship models are used to investigate the structural response against bow collision with variation of primary and secondary members. Mass and speed are also varied in two conditions. 2). 21 models conisted of 5 size of full scaled oil carriers are used to perform the collision simulation with the various sizes and deadweight delivered in a recent which are complied with SOLAS and MARPOL. 3). 36 models of 100k oil carrier are used to investigate the structural response and its influence to the collision bulkhead against bow collision in variation with location of collision bulkhead, primary mombers, framing system and colliding conditions, etc.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.670-676
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• 2016

Hydrogen town in Republic of Korea was established in 2013. Hydrogen as a byproduct produced by various processes of factories is used in hydrogen town facilities. As cell performance is affected by contaminations in fuel gas, various standards about impurities of fuel have been determined by many countries. This study shows performance degradation of single cell with impurities concentrations. Traces of carbon monoxide (CO) and hydrogen sulfide ($H_2S$)can cause considerable cell performance losses. For comparing the performances by poisoning of CO, acceleration test, I-V curve, constant current are performed. Both the CO and $H_2S$ poisoning rate are a function of their concentration. With the higher concentrations the higher poisoning rates are observed. And, it was confirmed that, oxidation behavior and side reaction generation are not affected. Under the lower $H_2S$ concentration condition, the poisoning rate is much higher than that of CO because of its different adsorption intensity. It can be possible that the result of this study can be used for enacting regulation as a baseline data.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.45-52
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• 2010

본 논문에서는 새로운 차량의 도입으로 건설되는 신형식 교량의 동적거동을 확인하기 위해 상용 유한요소 프로그램을 이용하여 해석을 실시하여 충격계수를 산정하였으며, 국내뿐만 아니라 각국에서 적용되고 있는 충격계수에 관한 설계기준을 조사하여 비교 검토하였다. 연구에서 제시되어진 교량형식은 파이프트러스 형식으로 각각 34m, 44m, 54m로 모델링하였으며 각각의 지간길이에 따른 충격계수의 영향을 산정하였다. 차량모델은 실제 교량 위를 통과하는 2축과 3축 저상굴절차량과 박영석(1997)이 제시한 147kN 덤프트럭 모델을 적용하였으며, 각 차량별로 10km/h~100km/h까지의 속도대역에 따른 충격계수를 산정하여 이에 따른 영향을 검토하였다. 또한 차량 및 지간길이에 따라 산정되어진 지간 중앙에서의 충격계수를 바탕으로 우리나라 및 외국의 설계규정과 비교 검토하였다.