• Current Applied Physics
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• v.18 no.11
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• pp.1268-1274
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• 2018

We have investigated the effects of chemical rounding (CR) on the surface passivation and/or antireflection performance of $AlO_{x^-}$ and $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters with two different boron doping concentrations, and on the performance of bifacial n-PERT Si solar cells with a front pyramid textured $p^+$-emitter. From experimental results, we found that chemical rounding markedly enhances the passivation performance of $AlO_x$ layers on pyramid textured $p^+$-emitters, and the level of performance enhancement strongly depends on boron doping concentration. Meanwhile, chemical rounding increases solar-weighted reflectance ($R_{SW}$) from ~2.5 to ~3.7% for the $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters after 200-sec chemical rounding. Consequently, compared to non-rounded bifacial n-PERT Si cells, the short circuit current density Jsc of 200-sec-rounded bifacial n-PERT Si cells with ~60 and ${\sim}100{\Omega}/sq$ $p^+$-emitters is reduced by 0.8 and $0.6mA/cm^2$, respectively under front $p^+$-emitter side illumination. However, the loss in the short circuit current density Jsc is fully offset by the increased fill factor FF by 0.8 and 1.5% for the 200-sec-rounded cells with ~60 and ${\im}100{\Omega}/sq$ $p^+$-emitters, respectively. In particular, the cell efficiency of the 200-sec-rounded cells with a ${\sim}100{\Omega}/sq$ $p^+$-emitter is enhanced as a result, compared to that of the non-rounded cells. Based on our results, it could be expected that the cell efficiency of bifacial n-PERT Si cells would be improved without additional complicated and costly processes if chemical rounding and boron doping processes can be properly optimized.

• Journal of Wetlands Research
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• v.23 no.3
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• pp.213-223
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• 2021

To understand the sedimentary environment of Scirpus planiculmis habitat (Myeongji and Eulsuk tidal flats) in the Nakdong Estuary, this study analyzed the statistical parameters (sorting, skewness, and kurtosis) of grain size data and the major (Al, Fe, Mn, Mg, Ca, Na, K, Ti, and P), minor (Li, Sc, V, Cr, Co, Ni, Cu, Zn, Sr, Zr, Cs, Pb, Th, and U), and rare earth elements (REEs) in sediment cores. For Myeongji, the sediment structure of the upper part of the cores was poorly sorted, more finely skewed, and more leptokurtic due to construction of the West gate. By contrast, the Eulsuk cores all differed due to the contrasting floodgate operation patterns of the West and East gates. The linear discriminate function (LDF) results corresponded to the statistical parameters for grain size. At the Eulsuk tidal flat (sites ES05 and ES11), elemental distributions were representative of Al-, Fe- and Ca-associated profiles, in which the elements are largely controlled by the accumulation of their host minerals (such as Na- and K-aluminosilicate and ferromagnesium silicate) and heavy detrital minerals at the sites. Detrital minerals including the aluminosilicates are major factors in the elemental compositions at ES05, diluting the REE contents. However, clay minerals and Fe-oxyhydroxides, as well as REE-enriched heavy minerals, appeared to be controlling factors of the elemental composition at ES11. Therefore, the mineral fractionation process is important in determining the elemental composition during sedimentation, which reflects the depositional condition of riverine-saline water mixing at both sites.

• The Journal of Korean Society for School & Community Health Education
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• v.22 no.4
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• pp.49-60
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• 2021

Objectives: Laboratories have various latent physical, chemical, biological, and ergonomical factors according to the diversification and fusion of research and development activities. This study aims to investigate the chemical exposure concentrations of college laboratories and evaluate their health risks, and use them as basic data to promote the health of college students. Methods: The sampling and analysis of harmful chemicals in the air in laboratories were performed using Method 1500 of the U.S. National Institute for Occupational Safety and Health (NIOSH)의 Method 1500. The harmful chemicals in the laboratories were divided into carcinogenic and non-carcinogenic chemicals. Risk assessment was performed using the cancer risk (CR) for carcinogenic chemicals and using the hazard index (HI) for non-carcinogenic chemicals. Results: The harmful chemicals in college laboratories consisted of acetone, diethyl ether, methylene chloride, n-hexane, ethyl acetate, chloroform, tetrahydrofuran, toluene, and xylenes. They showed the highest concentrations in laboratories A (acetone 0.001~2.34ppm), B (chloroform 0.95~6.35ppm), C (diethyl ether 0.08~8.68ppm), and D (acetone 0.07~14.96ppm). The risk assessment result for non-carcinogenic chemicals showed that the HI of methylene chloride was 2.052 for men and 2.333 for women, the HI of N-hexane was 4.442 for men and 5.05 for women. Thus, the HI values were higher than 1. The risk of carcinogenic chemicals is determined by an excess cancer risk (ECR) value of 1.0×10^-5, which means that one in 100,000 people has a cancer risk. The ECRs of chloroform exceeded 1.0×10^-5 for both men and women, indicating the possibility of cancer risk. Conclusion: College laboratories showed the possibility of non-carcinogenic health risks for methylene chloride, n-hexane, tetrahydrofuran (THF), toluene, and xylenes, and carcinogenic health risks for chloroform, methylene chloride. However, this study used the maximum values of measurements to determine the worst case, and assumed that the subjects were exposed to the corresponding concentrations continuously for 8 hours per day for 300 days per year. In consideration of the nature of laboratory environment in which people are intermittently exposed, rather than continuously, to the chemicals, the results of this study has an element of overestimation.

• The Journal of Internal Korean Medicine
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• v.43 no.3
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• pp.363-374
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• 2022

Objective: This study was conducted to evaluate the hypoglycemic effect and safety of herbal extracts in patients with type 2 diabetes mellitus. Methods: We investigated 19 hospitalized patients with type 2 diabetes mellitus who were administered Banhasasim-tang (BST), Gumiganghwal-tang (GGT), or Pyeongwee-san (PWS) at Kyung Hee University Korean Medical Hospital for at least three days between January 2012 and December 2021. Their clinical characteristics and laboratory tests were reviewed retrospectively. The glucose-lowering effect of the herbal extracts was assessed by comparing blood glucose levels, including fasting blood sugar (FBS), two-hour postprandial glucose (PP2) levels, and glycated hemoglobin levels. To evaluate the safety of the herbal extract, liver function test and kidney function test results were compared, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine (Cr). Results: After taking herbal extracts, PP2 and HbA1c levels significantly decreased from 205.82 mg/dL to 171.41 mg/dL and 7.58% to 6.62%, respectively. The safety profile reported no significant difference after taking herbal extracts. Conclusions: BST, GGT, and PWS may have hypoglycemic effects in patients with type 2 diabetes mellitus taking hypoglycemic medication.

• Fisheries and Aquatic Sciences
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• v.25 no.12
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• pp.626-636
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• 2022

Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.1
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• pp.75-85
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• 2010

The focus of this study is to evaluate the field applicability of the newly developed inorganic thixotropic-grout in various ways. In order to do this, the volume stability and the permeability of the inorganic thixotropic-grout have been measured and compared to the existing silica type grouts. In addition, the filling capability of the grout into the tail void has been evaluated through both an experiment with a miniature tail-void filling equipment and a test filling at the shield TBM construction site. The volume loss of the inorganic thixotropic-grout after a 14 day-curing under the atmosphere condition was appeared to be minimal. The excellent waterproofing ability of the inorganic thixotropic-grout was confirmed through a permeability test. The toxicity of the inorganic thixotropic-grout has been evaluated through a toxicity test of aquatic fishes (KS M 0111) and the pH value of the liquid eluviated from inorganic thixotropic-grout was measured as an average of 8.0 and a fatality rate of goldfish after 96 hours was 10% or so. The existence of harmful heavy metals in the liquid eluviated from the inorganic thixotropic-grout has been also examined through an atomic absorption spectroscopy (AAS) test. Any of harmful heavy metals were not detected and the detected level of $Cr^{6+}$ and Cd was far below the standard. Based on both an experiment with a miniature tail-void filling equipment and a test filling at the shield TBM construction site, the filling ability of inorganic thixotropic-grout into the tail void was proved to be excellent.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.19-19
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• 2021

경남 양산의 천성산에서만 생육하는 산림청·국립수목원 지정 희귀식물(Critically Endangered, CR) 주걱댕강나무 개체군을 대상으로 20개소의 방형구(10×10m, 100m²) 내 개체의 특성(개체수, 개화, 결실 등), 종자의 활력검정, 차광처리에 따른 생육 특성 및 우리나라 전역의 생육가능성에 대해 알아보았다. 20개소의 대상지에서 확인한 개체수는 총 3,270개체이며, 평균 개체밀도는 1.635/m²이다. 평균 수고는 1.1m 정도이며, 평균개화율은 27.37%이고 개화는 1.0~1.8m(평균수고 1.39m) 수고에서 집중되었다. 한편, 결실률은 평균 1.67%로 매우 낮았다. 종자의 크기는 평균 너비 0.27mm, 높이 0.18mm 정도로 너무 작아 X-ray 촬영을 통한 충실검정은 확인할 수 없었다. 종자를 1% Agar배지에 종자를 치상한 후 온도조건(15, 20, 25℃)에 따른 실험 및 온도(15, 20, 25℃)와 GA3 농도(100, 250, 500PPM)처리 실험 모두 발아율은 0%였다. 결실률이 매우 낮고, 종자 발아율 또한 낮으며 지하경을 뻗는 특성으로 보아 종자는 휴면종자이며 영양생장을 취하는 것으로 판단된다. 차광처리에 따른 생육 특성 실험 결과, 신초는 평균 30.6mm 성장, 엽록소 평균 함량 25.30, 잎의 수 평균 8.32개, 잎 길이 평균 35.93mm, 잎 폭 평균 20.37mm정도 성장하여 엽면적은 평균 761.10mm로 나타났다. 생육은 조도계를 활용한 실 차광률로 볼 때, 67.8% > 82.8% > 88.2% > 43.2% > 91.9%의 순서로 나타났다. 주걱댕강나무 자생지 내 수관열림도가 21.86%로 이를 차광률로 환산할 경우 70%내외의 차광률에서 생육이 효율적인 것을 확인하였다. 기후대별로 5개소에 이식한 주걱댕강나무는 이듬해까지 모두 생육이 원활하였다. A. spathulata를 Diabelia ionostachya종들과 가까운 유연관계를 가진다는 연구에서 D. ionostachya 샘플은 위도상 강원도 고성군에 속하고 있어 우리나라 대부분 지역에서 식재가 가능할 것으로 판단된다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.21-21
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• 2021

주걱댕강나무는 경남 양산의 천성산에서만 생육하는 산림청·국립수목원 지정 희귀식물(Critically Endangered, CR)로 현지외 보전 및 대체 서식지 조성을 위해 번식 특성에 대해 알아보았다. 종자번식의 경우 450립의 종자를 저장방법에 따라 파종한 결과 노천매장 3.56%, 저온건조저장 0.67%, 습사저온저장 0.22%로 발아율이 매우 저조하였으며, 배양토 조건에 따라 직파 실험한 결과 모래 2.44%, 원예용 상토 2.22%, 현지내 산림토 1.11%, 현지외 산림토 0%로 이 또한 발아율이 매우 저조하였다. 삽목번식의 경우 숙지삽은 모래+펄라이트 36.1%, 모래 31.1%, 원예용 상토 20.0%로 나타났으며, 휴면지 삽수의 발근촉진제 처리 효과는 IBA 1,000PPM에서 37.8%, IBA 7,000PPM 30.0%, 무처리 28.9%, IBA 5,000PPM 27.8%의 발근율을 보였고 신초길이, 뿌리의 수, 뿌리 길이는 전반적으로 발근촉진제 처리와 함께 농도가 높아질수록 뿌리 성장이 왕성한 것으로 나타났다. 녹지삽은 모래 80%, 모래+펄라이트 76.7%, 피트모스+마사토 73.3%, 피트모스+펄라이트+버미큘라이트 70.0% 순이며, 왕모래와 왕모래+마사토는 26.7%와 36.7%로 다소 저조하였다. 녹지삽수의 굵기는 4mm이상 구간에서 발근율이 73.3%로 가장 높았으며, 녹지삽수의 길이는 7~8cm 구간에서 80.0%로 가장 높게 나타나 삽수의 굵기가 굵고 8cm내외의 길이가 효율적인 것으로 나타났다. 근삽은 발아율이 88.3~96.7%로 모든 배양토에서 높게 나타났다. 근삽수 직경 7~8mm에서 100%이며 3~4mm 또한 91%로 나타났다. 근삽수 길이는 4~5cm와 10~11cm에서 100%, 6~7cm 88.1%, 8~9cm 94.4%로 나타나 4~5cm를 제외하고는 삽수 길이가 길수록 신초 생장과 발근이 비례하는 것을 확인하였다. 주걱댕강나무는 실생보다 삽목번식이 더 효율적이며, 그 중 근삽이 가장 발근율이 높다. 배양토는 모래 단용구를 제외하고는 평균 95%이상으로 나타났으며, 근삽수는 직경이 굵고 길수록 신초 생장과 발근이 왕성하다. 따라서, 현지외 보전을 위해 향후 휴면성의 종자 발아 연구가 필요하며, 영양번식을 할 경우 근삽이 가장 효율적인 것을 확인하였다.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.3
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• pp.45-56
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• 2024

Heavy metals emitted from urban development do not decompose in the soil and remain for long periods, continually impacting the environment. Since the mid-1990s, there has been increasing societal concern in South Korea regarding soil contamination, prompting various legislative revisions to reduce pollution. This study utilizes the Environmental Impact Assessment Support System (EIASS) to investigate projects in the metropolitan area that have exceeded the Ministry of Environment's soil contamination concern levels from 1989 to 2022 and to examine improvements in the environmental impact assessment (EIA) process. The results reveal that the average concentrations of nine contaminants-cadmium (Cd), copper (Cu), arsenic (As), mercury (Hg), lead (Pb), hexavalent chromium (Cr6+), zinc (Zn), nickel (Ni), and fluoride (F)-have all increased over the years. Among these, Zn had the highest relative proportion, with 37.5% of the 40 sites exceeding environmental concern levels. Investigation of 19 specific projects at these exceedance sites showed that only 7 had documented analyses of contamination causes and remediation plans, and just one had contracted additional remediation services, though results from these efforts were found to be lacking. Furthermore, since 2019, a significant proportion of these sites were involved in residential developments, likely due to government initiatives in new city development and extensive housing supply plans. This research emphasizes the importance of public disclosure of the processes and outcomes of remediation efforts on historically contaminated soils prior to project development. It discusses improvements to the EIA by reviewing current legislation and international examples. The findings of this study are expected to heighten public awareness about heavy metal contamination and enhance transparency in soil remediation efforts, contributing to sustainable environmental management and development.