• Journal of Nutrition and Health
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• 제50권6호
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• pp.578-584
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• 2017

Purpose: Excess intake of sodium is a major diet-related risk factor for human diseases including hypertension and cancer as well as obesity and inflammation. However, findings are still controversial, and evidence is lacking in Koreans. Therefore, for better understanding of the role of dietary sodium intake in disease etiology, this study investigated the effects of dietary sodium intake on adiposity, inflammation, and hormones in Koreans. Methods: A total of 80 males and females joined the study. The general characteristics and dietary intake data were investigated by trained interviewers using a questionnaire and 24-h dietary recall, respectively. For the markers of adiposity, body weight, body mass index, percent of body fat, visceral fat area, and waist and hip circumference were measured. For the inflammation and hormone markers, leptin, adiponectin, insulin, tumor necrosis $factor-{\alpha}$, and interleukin-6 were also analyzed. Results: Multivariate linear regression analyses suggested that dietary sodium intake was not associated with adiposity. However, dietary sodium showed a significant association with insulin level: Plasma insulin concentration increased with sodium intake independent of other dietary intake or percent of body fat (${\beta}=0.296$, adjusted $r^2=0.276$, p < 0.01). Other markers for inflammation and hormonal responses were not associated with dietary sodium intake. Conclusion: Findings suggested that dietary sodium intake may be a critical modifying factor in the level of plasma insulin. However, it showed a limited effect on obesity and other inflammation markers and hormone levels. These findings should be confirmed in larger, well-designed investigations.

• 한국터널지하공간학회 논문집
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• 제7권1호
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• pp.63-72
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• 2005

본 논문에서는 국내 ${\bigcirc}{\bigcirc}$ 댐 여수로 터널에서 가능최대홍수량 (PMF) 발생시 내부수압이 터널 구조물에 미치는 영향을 3차원 유한차분해석을 통하여 검토하였다. 내부수압을 합리적으로 결정하기 위하여 도수터널에서의 1차원 수치모형을 적용한 HEC-RAS 프로그램을 이용하여 가능최대홍수량 발생시 터널측벽에 발생하는 최대하중을 산정하고, 이를 터널 내부에 하중으로 재하하였다. 여수로 터널은 쌍굴터널로서, 단계별 굴착 및 지보재 시공순서를 고려하였고, 왼쪽 터널에만 수압이 작용하는 경우 (CASE-1), 오른쪽 터널에만 수압이 작용하는 경우 (CASE-2) 및 동시에 수압이 작용하는 경우 (CASE-3)으로 나누어 각각 해석을 수행하였다. 해석결과, 각 터널에서 발생하는 최대인장응력 및 최대부재력을 허용치와 비교하여 구조물의 안정성을 평가하고 응력집중구간 및 취약부를 파악하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권2호
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• pp.103-108
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• 2007

Cyclooxygenase-2 (Cox-2) is known as one of the critical factor in carcinomas of various organs. However, the importance of Cox-2 in oral squamous cell carcinoma has not been fully described yet. The purpose of this study is to evaluate the anti-cancer effect of selective cox-2 inhibitor, celecoxib in an oral squamous cell carcinoma cell line, KB with respect to cytotoxicity test, in vitro invasion and MMP-2 expression. In cytotoxicity test, celecoxib treated group showed definitely concentration dependent cytotoxicity. In addition, administration of celecoxib reduced the invasive potential of KB cell line significantly in invasion assay. However, there was no remarkable difference of the MMP-2 expression between the celecoxib treated group and the control group. Considering these data, celecoxib had a potential cytotoxic agent to oral squamous cell carcinoma cells. Also, it had anti-invasive property without acting on the MMP-2 expression mechanism. Therefore, it was postulated that celecoxib had the possibility of anti-cancer agent in treatment strategies of oral squamous cell carcinoma.

• 펄프종이기술
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• 제42권5호
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• pp.74-82
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• 2010

Curtain stability without curtain contraction is critical for a successful operation in curtain coating, and this can be influenced by the change in particle dynamics and rheological properties of coating colors. In this study, polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) were added to control the rheology of GCC based curtain coating colors. Surface tension was increased slightly with increasing content of cobinder. Shear-thinning of viscosity was more pronounced for the CMC containing GCC coating colors. Complex modulus decreased when small amount of PVA was used as a cobinder, but it increased in other coating colors. Extensional viscosity was increased with increasing of the cobinder content, but CMC was more effective. Results indicate that pigment interaction with PVA is different from that with CMC. Dispersibility of coating colors was improved due to steric stabilization when small amounts of PVA was used, but flocculation occurred by bridging when the amount of PVA was increased. Dispersibility of coating colors was improved when small amount of CMC was added, while flocculation was observed by depletion effect when the concentration of CMC was increased in coating colors. Addition of cobinders at proper levels gave positive effects both in rheological properties and curtain stability. On the other hand, excessive amount of cobinders caused particle flocculation and this resulted in rheological and curtain stablity problems.

• 한국수자원학회논문집
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• 제54권9호
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• pp.643-656
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• 2021

최근 국내 상수도 관리 기술은 고도로 발달하고 있으며, 이 과정에서 상수관망 내 용수공급 현황을 파악하고 예측하기 위한 컴퓨터 수리·수질 해석 모형은 핵심적인 역할을 수행하고 있다. 그러나 대규모 네트워크의 경우 컴퓨터 해석모형의 부담을 가중하고, 특히 짧은 계산시간 간격과 긴 모의 시간이 요구되는 수질해석의 경우, 막대한 계산시간이 소요되어 다양한 수질모의 및 분석이 어려운 경우가 발생한다. 본 연구에서는 대규모 상수관망시스템의 수질해석의 계산효율을 개선하기 위해 상수도 공급계통을 2단계로 계층화한 후, 계층화된 네트워크를 대상으로 수질모의를 수행하는 계층적 수질모의 기법을 제안하였다. 제안된 모의기법은 국내 대규모 상수도 네트워크에 적용하였으며, 다양한 염소투입농도 시나리오에 따른 잔류염소농도의 시공간적 분포를 모의하고 분석한 결과를 제시하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.48-48
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• 2023

The intensified droughts under climate change are expected to threaten stable water resource availability. Droughts exceeding the magnitude of historical variability could occur increasingly frequently under future climate conditions. It is crucial to understand how drought will evolve over time because the assumption of hydrological stationarity of the past decades would be inappropriate for future water resources management. However, the timing of the emergence of unprecedented drought conditions under climate change has rarely been examined. Here, using multimodel hydrological simulations, we investigate the changes in the frequency of hydrological drought (defined as abnormally low river discharge) under high and low greenhouse gas concentration scenarios and with existing water resources management and estimate the timing of the first emergence of unprecedented regional drought conditions that persist for over several consecutive years. This new metric enables a new quantification of the urgency of adaptation and mitigation with regard to drought under climate change. The times are detected for several sub-continental-scale regions, and three regions, namely, southwestern South America, Mediterranean Europe, and northern Africa, exhibit particularly robust and earlier critical times under the high-emission scenario. These three regions are expected to confront unprecedented conditions within the next 30 years with a high likelihood, regardless of the emission scenarios. In addition, the results obtained herein demonstrate the benefits of the lower-emission pathway in reducing the likelihood of emergence. The Paris Agreement goals are shown to be effective in reducing the likelihood to the unlikely level in most regions. Nevertheless, appropriate and prior adaptation measures are considered indispensable to when facing unprecedented drought conditions. The results of this study underscore the importance of improving drought preparedness within the considered time horizons.

• 한국산업보건학회지
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• 제24권4호
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• pp.453-461
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• 2014

Objective: Based on the fact that fine particles are more likely to produce negative influences on the health of occupants as well as the quality of indoor air compared to coarse particles, it is critical to determine concentrations of aerosol particles with different sizes. Thus, this study focused on the size distribution and concentrations of aerosol particles in university buildings. Method: Aerosol particles in indoor air were collected from four areas: corridors in buildings(In-CO), lecture rooms(In-RO), laboratories(In-LR), and a cafeteria(In-RE). Samples were also collected from outside for comparison between the concentrations of indoor and outdoor particles. For the collection of the samples, an eight stage non-viable cascade impactor was used. Result: The average concentration of $PM_{10}$ in the samples collected from indoor areas was $34.65-91.08{\mu}g/m^3$,and the average for $PM_{2.5}$ was $22.65-60.40{\mu}g/m^3$. The concentrations of the aerosol particles in the corridors, lecture rooms, and laboratories were relatively higher than the concentrations collected from other areas. Furthermore, in terms of mass median aerodynamic diameter(MMAD), the corridors and lecture rooms had higher numbers due to their characteristics, showing $2.36{\mu}m$ and $2.11{\mu}m$, respectively. Laboratories running an electrolysis experiment showed $1.58{\mu}m$, and the cafeteria with regular maintenance and ventilation had $1.96{\mu}m$. Conclusion: The results showed that the $PM_{10}$ concentrations of all samples did not exceed indoor air quality standards. However, the $PM_{2.5}$ concentration was over the standard and, in particular, the concentration of fine particles collected from the laboratories was relatively higher, which could be an issue for the occupants. Therefore, it is important to improve the quality of the indoor air in university buildings.

• Asian-Australasian Journal of Animal Sciences
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• 제10권5호
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• pp.445-454
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• 1997

Rice bran commonly available in Bangladesh is a mixture of rice hulls (60%), bran (35%) and polishing (5%), referred here as rice mill feed (RMF). Dose response effect of RMF supplementation to a straw diet including a zero level was measured on the intake, digestibility, nitrogen balance, microbial N yield and growth rate of growing native (Bos indicus) bulls. Twelve bulls of 33 months old and $272{\pm}31.5kg$ weight were randomly allocated to diets having 0 (T1), 1 (T2) and 2 (T3) kg RMF in addition to 200 g wheat bran, 200 g molasses, 60 g salt and 30 g oyestershe\l powder. Concentrate intake was 5.5, 19.2 and 29.5% of the dietary intake for the T1, T2 and T3 treatment respectively. RMF supplementation had no significant effect on the straw DM intake. However, with the increasing levels of RMF supplementation, total DM & digestible OM intake and the whole gut digestibilities of DM, OM, N & ADF increased but in deminishig return. Total microbial N yield estimated from the urinary purine excretion were 15.35, 26.56 and 38.44 g/d for the treatment T1, T2 and T3 respectively. Both the N intake and the N balance increased linearly in response to increasing level of RMF. Supplementation of RMF linearly increased the energy intake and dietary energy concentration. Growth rate in the T1, T2 and T3 treatments were 112, 125 and 250 g/d respctively. The basal N excretion and the maintenance energy requirement of the experimental animals were estimated to be 615 mg/kg $W^{0.75}/d$ and 447 kJ/kg $W^{0.75}/d$ respectively. The estimated efficiency on N utilization was 0.83 mg/mg of N intake ($r^2=0.997$) while the efficiency of metabolizable energy utilization for growth was 0.15. Since animal refused higher levels of RMF, inclusion up to 2 kg level (about 25% of the total DM intake) appears to have no depressing effect on the performances of animal. However, RMF itself fail to meet the critical nutrient need of the rumen microbes. Therefore response of supplementing RMF after correcting the critical nutrient deficiency need to be studied.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2006년도 춘계학술대회 논문집
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• pp.55-56
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• 2006

This thesis describes the use of measured aerosol size distributions and size-resolved hygroscopic growth to examine the physical and chemical properties of several particle classes. The primary objective of this work was to investigate the optical and cloud forming properties of a range of ambient aerosol types measured in a number of different locations. The tool used for most of these analyses is a differential mobility analyzer / tandem differential mobility analyzer (DMA / TDMA) system developed in our research group. To collect the data described in two of the chapters of this thesis, an aircraft-based version of the DMA / TDMA was deployed to Japan and California. The data described in two other chapters were conveniently collected during a period when the aerosol of interest came to us. The unique aspect of this analysis is the use of these data to isolate the size distributions of distinct aerosol types in order to quantify their optical and cloud forming properties. I used collected data during the Asian Aerosol Characterization Experiment (ACE-Asia) to examine the composition and homogeneity of a complex aerosol generated in the deserts and urban regions of China and other Asian countries. An aircraft-based tandem differential mobility analyzer was used for the first time during this campaign to examine the size-resolved hygroscopic properties of particles having diameters between 40 and 586 nm. Asian Dust Above Monterey (ADAM-2003) study was designed both to evaluate the degree to which models can predict the long-range transport of Asian dust, and to examine the physical and optical properties of that aged dust upon reaching the California coast. Aerosol size distributions and hygroscopic growth are measured in College Station, TX to investigate the cloud nucleating and optical properties of a biomass burning aerosol generated from fires on the Yucatan Peninsula. Measured aerosol size distributions and size-resolved hygroscopicity and volatility were used to infer critical supersaturation distributions of the distinct particle types that were observed during this period. The predicted CCN concentrations were used in a cloud model to determine the impact of the different aerosol types on the expected cloud droplet concentration. RH-dependent aerosol extinction coefficients are calculated at a wavelength of 550 nm.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.523-528
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• 2005

Diblock copolymers with different poly($\varepsilon$-caprolactone) (PCL) block lengths were synthesized by ringopening polymerization of $\varepsilon$-caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG-OH, MW 2000) as initiator. The self-aggregation behaviors of the diblock copolymer nanoparticle, prepared by the diafiltration method, were investigated by using $^1H$ NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG-PCL block copolymers formed the nano-sized self-aggregate in an aqueous environment by intrsa- and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations (cac) of the block copolymer self-aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The hydrodynamic diameters of the block copolymer nanoparticles, measured by DLS, were in the range of 65-270 nm. Furthermore, the size of the nanoparticles was scarcely affected by the concentration of the block copolymers in the range of 0.125-5 mg/mL owing to the negligible interparticular aggregation between the self-aggregated nanoparticles. Considered with the fairly low cac and nanoparticle stability, the PEG-PCL nanoparticles can be considered a potential candidate for biomedical applications such as drug carrier or imaging agent.