• 한국수자원학회논문집
• /
• 제51권2호
• /
• pp.131-140
• /
• 2018

강우는 물순환 시스템을 이해를 증가 시킬 뿐만 아니라, 효율적인 수자원 확보 및 관리에 있어서 가장 핵심적인 인자이다. 본 연구는 2015년을 대상으로 한반도에서의 92개의 ASOS 지점자료와 최근에 발사된 GPM 위성강우 자료의 비교를 통하여 활용가능성을 평가하였다. 또한 지점 자료의 장점과 인공위성 자료의 장점을 융합함으로써 보다 개선된 강우자료를 산출하기 위해 3가지의 상세화 방법(Geographical Differential Analysis, Geographical Ratio Analysis, Conditional Merging)들을 적용하였다. 이 연구에서 도출된 결과는 다음과 같다. 1) ASOS 자료와의 검증을 통해 GPM 강우자료가 약간 과대산정되는 편향을 가지고 있는 것을 확인하였으며, 특히 여름 기간에 오차가 높게 발생하는 것으로 나타났다. 2) Jackknife 방법을 통하여 각 합성방법에 대해서 검증하였을 때, 공간해상도가 높아짐에 따라서 오차가 줄어드는 것을 확인하였으며, 상세화 방법 중 conditional merging 방법이 가장 좋은 성능을 나타내었다.

• 한국가시화정보학회지
• /
• 제17권3호
• /
• pp.24-31
• /
• 2019

Recently, an air-lift bio-reactor operated by micro bubbles has been utilized to product hydrogen fuel. To enhance the performance, characteristics of hydrodynamics inside the bio-reactor were analyzed using a numerical simulation for two-phase flow. An Eulerian model was employed for both of liquid and gas phases. The standard k-ε model was used for turbulence induced by micro bubbles. A Population Balance Model was employed to consider size distribution of bubbles. A hollow cylinder was introduced at the center of the reactor to reduce a dead area which disturbs circulation of CO bubbles. An appropriate diameter of the draft tube and hollow cylinder were optimized for better performance of the bio-reactor. The optimum model could be obtained when the cross-sectional area ratio of the hollow cylinder to the reactor, and the width ratio of the riser to the downcomer approached 0.4 and 3.5, respectively. Consequently, it is expected that the optimum model could enhance the performance of the bio-reactor with the homogeneous distribution and higher density of CO, and more effective mixing.

• 대한수학교육학회지:수학교육학연구
• /
• 제25권1호
• /
• pp.21-58
• /
• 2015

본 연구는 초등학교 수학에서 비례 추론 지도를 위해 고려해야 할 교수학적 배경을 알아보고, 이를 바탕으로 우리나라와 미국, 영국 교과서의 비와 비례 관련 내용을 분석함으로써 앞으로 우리나라 초등학교 수학에서 비례 추론 지도 개선을 위한 시사점을 제공하는 데 그 목적이 있다. 이를 위해 여러 연구에 대한 이론적 고찰을 통해 비례 추론 지도의 교수학적 배경으로 비례 추론의 의미와 요소, 비례 추론 발달 단계와 학생들의 전략, 비례 추론 과제 유형, 비례 추론 지도 모델에 대해 살펴보았고, 이를 기초로 미국, 영국, 우리나라 교과서를 분석하였다. 이론적 고찰과 교과서 분석 결과를 바탕으로 이후의 우리나라 초등학교 수학에서 비례 추론 지도 개선을 위한 시사점으로 비와 비례 내용의 비중 제고, 곱셈적 비교의 강조와 덧셈적 비교와의 구분, 비의 동치 관계의 강조, 양적 질적, 대수적 기하적 비교 과제와 미지값 과제의 적절한 균형, 비례식의 성질을 이용한 형식적 절차 도입 전 비형식적 전략의 강조, 비형식적 전형식적인 시각적 모델의 도입을 제안하였다.

• 대한수학교육학회지:수학교육학연구
• /
• 제23권4호
• /
• pp.505-516
• /
• 2013

이 연구는 비례 추론의 본질이 무엇이며, 비례 추론이 어떻게 발달하는지를 알아보고 비례 추론을 개발하기 위한 요인 중 과제 요인에 초점을 맞춰 지도 방향이 초등학교 수학 교과에서 어떠해야하는지를 알아보기 위한 것이다. 비례 추론은 비례, 비, 비율, 비례식과 관계된 추론으로서, 공변과 다중 비교의 의미를 포함하는 양적 및 질적 추론이다. 2007 개정 교육과정에 따른 교과서에서는 비와 비율, 비례식, 정비례와 반비례 등 비례 추론과 관련된 내용을 지도하고 있으나 닮음, 속도, 농도, 확대도와 축도 등 다른 교과와 관련된 내용들은 지도하지 않거나 약화시키고 있다. 공변과 관련된 내용은 비와 정비례, 반비례 등에 포함되어 있으나 전개 방식이 동적이라기보다는 정적인 방식이다. 특히 비례식에서는 알고리즘에 의해 결측치를 구하는 데 치중하고 동치인 비를 생각하고 양변의 구조적 유사성을 의식하도록 유도하지는 않는다. 또한 비를 비형식적으로 비교해보거나 비례 상황과 비비례 상황을 구별하는 활동을 찾아볼 수 없다. 초등학교 학생들의 비례 추론을 육성하기 위해서는 교육과정과 교과서 개발 작업에서 이를 뒷받침할 필요가 있다.

• Nuclear Engineering and Technology
• /
• 제41권5호
• /
• pp.729-738
• /
• 2009

Given the evolution of High-Temperature Gas-cooled Reactor(HTGR) designs, the source terms for licensing must be developed. There are three potential source terms: fission products, actinides in the fuel and tritium in the coolant. It is necessary to provide first an inventory of the source terms under normal operations. An analysis of source terms has yet to be performed for HTGRs. The previous code, which can estimate the inventory of the source terms for LWRs, cannot be used for HTGRs because the general data of a typical neutron cross-section and flux has not been developed. Thus, this paper uses a combination of the MCNP, ORIGEN, and MONTETEBURNS codes for an estimation of the source terms. A method in which the HTR-10 core is constructed using the unit lattice of a body-centered cubic is developed for core modeling. Based on this modeling method by MCNP, the generation of fission products, actinides and tritium with an increase in the burnup ratio is simulated. The model developed by MCNP appears feasible through a comparison with models developed in previous studies. Continuous fuel management is divided into five periods for the feeding and discharging of fuel pebbles. This discrete fuel management scheme is employed using the MONTEBURNS code. Finally, the work is investigated for 22 isotope fission products of nuclides, 22 actinides in the core, and tritium in the coolant. The activities are mainly distributed within the range of $10^{15}{\sim}10^{17}$ Bq in the equilibrium core of HTR-10. The results appear to be highly probable, and they would be informative when the spent fuel of HTGRs is taken into account. The tritium inventory in the primary coolant is also taken into account without a helium purification system. This article can lay a foundation for future work on analyses of source terms as a platform for safety assessment in HTGRs.

• 자원리싸이클링
• /
• 제23권1호
• /
• pp.48-57
• /
• 2014

본 연구에서는 고밀도 폴리에틸렌 제조공정에서 부산물로 생성되는 폴리에틸렌 왁스를 대상으로 무수말레인산을 그라프트 반응 시킬 때, 반응 용매가 가지는 성질의 영향에 대해서 조사하였다. 측정결과, 자일렌이 톨루엔보다 우수한 모노머 용해성, 팽윤성, 혼화성을 가지며, 그라프트 반응을 더욱 촉진함을 알 수 있었고, 반응 용매의 함량에 따라서는 0 ~ 200% v/w영역에서 200% v/w 조건이 최대의 그라프트 율을 보이고, 그이상의 용매가 사용될 경우에는 그라프트 율이 다시 감소하다가 일정해짐을 확인하였다. 가교도 함량 값은 용매 존재 하에 거의 생성되지 않았으며, 용매가 용매분자로 사슬이동반응 시켜 가교반응을 방지하는 것으로 판단되었다. $140^{\circ}C$에서 측정된 용융 점도 값은 폴리에틸렌 왁스에 무수말레인산이 그라프트 된 후에 증가하는 경향을 보임을 알 수 있었다.

• 한국환경보건학회지
• /
• 제46권4호
• /
• pp.388-397
• /
• 2020

Objectives: The aim of this study was to assess the association between the use of heated tobacco products (HTP) and suicidal behaviors such as suicidal ideation, suicide planning, and suicide attempts among adolescents in South Korea. Methods: The study used a cross-sectional design. Data was from the 15th Korea Youth Risk Behavior Web-based Survey (KYRBS) performed in 2019 by the Ministry of Education, Ministry of Health and Welfare, and Korean Center for Disease Control and Prevention. Heated tobacco product use was used as a main independent variable and suicide-related behaviors such as suicidal ideation, planning, and attempts were applied as dependent variables. Out of 60,100 students, 57,303 responded. Results: HTP use significantly increased the odds of a suicide attempt and suicide planning among adolescents. After controlling for confounders, when comparing 'current HTP users' with 'never HTP users', the adjusted odds ratio (OR) was 1.78 (95% confidence interval (CI): 1.38-2.30) for suicide attempts among adolescents. After controlling the confounders, comparing 'current HTP users' with 'never HTP users', the adjusted OR was 1.36 (95% CI: 1.06-1.73) for suicide planning among adolescents. For sadness/despair among adolescents, when comparing 'current HTP users' with 'never HTP users', the adjusted OR was 1.29 (95% CI: 1.11-1.50). However, HTP use had no significant association with suicidal ideation among adolescents. Conclusions: Current HTP users were more likely to attempt to commit suicide, and more likely to plan to commit suicide than never HTP users among adolescents. These results may be useful in developing a scientific basis for designing suicide prevention programs targeting adolescents.

• 한국환경과학회지
• /
• 제22권4호
• /
• pp.471-479
• /
• 2013

The present study was conducted to judge the applicability of field quality control by children's goods manufacturers by assessing the contents of heavy metals such as Pb and Cd in outdoor play goods for children through measurement using Portable XRF and comparing the results through detailed analyses using ICP. Heavy metal contents of 711 part samples of 505 products were measured using XRF. According to the results, the ratio of products that exceeded the Pb and Cd content standards specified under the Quality Management and Safety Control of Industrial Products Act were 2.4% and 2.6%. Many products certified for self-regulated safety exceeded the standards and thus it was considered that harmful chemical material centered safety management systems would be necessary. Detailed ICP analyses of some products were compared and the results showed deviations of 0.9~80.8% from XRF results. The reasons for this are deviations in the characteristics of measured cross sections and the homogeneity of samples resulting from sample preparation methods, etc. Therefore, it is considered that field quality control will be applicable if measuring methods are efficiently established based on product characteristics and calibration curve preparation methods are established through quality control.

• 한국미생물·생명공학회지
• /
• 제45권4호
• /
• pp.358-364
• /
• 2017

Asymmetric PCR preferentially amplifies one DNA strand for use in DNA hybridization studies. Linear-After-The-Exponential-PCR (LATE-PCR) is an advanced asymmetric PCR method which uses innovatively designed primers at different concentrations. This study aimed to optimise LATE-PCR parameters to produce single-stranded DNA of Candida spp. and Aspergillus spp. for detection via probe hybridisation. The internal transcribed spacer (ITS) region was used to design limiting primer and excess primer for LATE-PCR. Primer annealing and melting temperature, difference of melting temperature between limiting and excess primer and concentration of primers were optimized. In order to confirm the presence of single-stranded DNA, the LATE-PCR product was hybridised with digoxigenin labeled complementary oligonucleotide probe specific for each fungal genus and detected using anti-digoxigenin antibody by dot blotting. Important parameters that determine the production of single-stranded DNA in a LATE-PCR reaction are difference of melting temperature between the limiting and excess primer of at least $5^{\circ}C$ and primer concentration ratio of excess primer to limiting primer at 20:1. LATE-PCR products of Candida albicans, Candida parapsilosis, Candida tropicalis and Aspergillus terreus at up to 1:100 dilution and after 1 h hybridization time, successfully hybridised to respective oligonucleotide probes with no cross reactivity observed between each fungal genus probe and non-target products. For Aspergillus fumigatus, LATE-PCR products were detected at 1:10 dilution and after overnight hybridisation. These results indicate high detection sensitivity for single-stranded DNA produced by LATE-PCR. In conclusion, this advancement of PCR may be utilised to detect fungal pathogens which can aid the diagnosis of invasive fungal disease.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권18호
• /
• pp.8365-8370
• /
• 2016

Background: Shammah is a traditional form of snuff dipping tobacco (a smokeless tobacco form) that is commonly used in Yemen. Oral mucosal changes due to the use of shammah can usually be observed in the mucosal surfaces that the product touches. The aim of this study was to determine the association between shammah use and oral leukoplakia-like lesions. Other associated factors were also determined. Materials and Methods: A cross sectional study was conducted on 346 randomly selected adult males. Multi-stage random sampling was used to select the study location. After completing the structured questionnaire interviews, all the participants underwent clinical exanimation for screening of oral leukoplakia-like lesions Clinical features of oral leukoplakia-like lesion were characterized based on the grades of $Ax{\acute{e}}ll$ et al (1976). Univariable logistic regression and multivariable logistic regression were used to assess the potential associated factors. Results: Out of 346 male participants aged 18 years and older, 68 (19.7%) reported being current shammah users. The multivariable analysis revealed that age, non-formal or primary level of education, former shammah user, current shammah user, and frequency of shammah use per day were statistically associated with the presence of oral leukoplakia-like lesions [Adjusted odds ratio (AOR) = 1.03; 95% confidence interval (CI) : 1.01, 1.06; P=0.006], (AOR=8.65; 95% CI: 2.81, 26.57; P=0.001), (AOR=3.65; 95% CI: 1.40, 9.50; P=0.008), (AOR=12.99; 95% CI: 6.34, 26.59; P=0.001), and (AOR=1.17; 95% CI: 1.02, 1.36; P=0.026), respectively. Conclusions: The results revealed oral leukoplakia-like lesions to be significantly associated with shammah use. Therefore, it is important to develop comprehensive shammah prevention programs in Yemen.