• 생태와환경
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• 제40권4호
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• pp.527-536
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• 2007

In this study, we applied 10-metric health assessment model, based on the Index of Biological Integrity (IBI) during 2006 in the Changwon Stream, which is located in the Changwon city, Gyeongnam province, S. Korea, and then compared with water quality data. The Index of Biological Integrity (IBI) in the Changwon Stream varied from 18 to 38 in the watershed depending on the sampling location and averaged 30.3 (n=6) during the study. Analysis of tolerance guilds showed that the proportion of sensitive species was 13%, but tolerant and intermediate species were 34% and 53%, respectively. Qualitative Habitat Evaluation Index (QHEI) averaged 43.3 (range: 65-104, n=6) indicating non-supporting condition, based on the criteria of U.S. EPA (1993). Values of QHEI showed a typical longitudinal decreases from the headwater reach to the downstream location, except for Site 1 with a low QHEI value by artificial habitat by concrete construction. Minimum QHEI was found in Site 4 where fish diversity was minimal. Conductivity increased continuously along the gradients and especially showed abrupt increases in the downstream sites along with turbidity. Stream ecosystem health of IBI matched to the values of QHEI except for S6. Low IBI values in the sites 4 and 5 was considered to be a result of combined effects of chemical pollutions and habitat degradations. Our results support the hypotheses of Plafkin et ai. (1989) that physical habitat quality directly influences the trophic structure and species richness, and is closely associated with IBI values.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.79-79
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• 2017

Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

• 한국물환경학회지
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• 제18권3호
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• pp.245-251
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• 2002

Reactive dyes waste water, a toxic and refractory pollutant, was treated by an electrochemical method using $Ti/IrO_2$ as anode and Stainless Steel 316 as cathode. In this technique, sodium chloride as an electrolyte was added. A number of experiments were run in a batch system. Artificial samples (reactive blue 19, red 195, yellow 145) were used. Operation parameters, such as supporting electrolyte concentration, current density, pH and sample concentration have been investigated for their influences on COD and color removal efficiencies during electrolysis. After 5 and 90 minites of eletrolysis, color was reduced by 51.5% and 98.9% respectively. Under the condition of current density $10A/dm^2$, NaCl concentration 12mg/l and pH 3, 62.9% of $COD_{Cr}$ was removed after electrolysis for 90 minites. The optimum condition of color removal and COD reduction in this work was found to be the following : pH 3, sodium chloride concentration 20g/l, current density $10A/dm^2$. As a result, we confirmed to be effective to color removal and reduction of refractory organic material.

• 아시안잔디학회지
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• 제20권2호
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• pp.253-264
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• 2006

우리나라의 대부분의 골프장은 법적, 경제적 이유로 건설부지가 계곡과 능선 또는 봉우리를 포함할 수밖에 없는 실정이다. 계곡과 능선은 생태계에 있어서 매우 중요한 부분을 차지하고 있으므로 이를 훼손하는 것은 생태환경의 변화에 큰 영향을 미치게 된다. 따라서 골프장 공사로 인해 발생하는 훼손을 최소화하고 기존의 계곡 또는 하천이 하던 생태적 기능을 수행할 수 있는 생태복원형 하천을 환경보상적 차원에서 설치하는 것이 매우 중요하다. 본 논문에서는 골프장 내의 하천을 생태하천으로 복원하기 위해 고려해야할 사항과 적합한 공법 및 사례를 통하여 골프장건설로 인한 환경영향을 최소화하고 자연환경과 조화를 통하여 최적의 골프장을 조성할 수 있도록 설계도면 실례를 들어 제안하였다.

• Laboraroty Animal Research
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• 제34권4호
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• pp.257-263
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• 2018

Trefoil factor 1 (TFF1, also known as pS2) is strongly expressed in the gastrointestinal mucosa and plays a critical role in the differentiation of gastric glands. Since approximately 50% of all human gastric cancers are associated with decreased TFF1 expression, it is considered a tumor suppressor gene. Tff1 deficiency in mice results in histological changes in the antral and pyloric gastric mucosa, with severe hyperplasia and dysplasia of epithelial cells, resulting in the development of antropyloric adenoma. Here, we generated Tff1-knockout (KO) mice, without a neomycin resistant ($Neo^R$) cassette, using the clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9 (CRSIPR/Cas9) system. Though our Tff1-KO mice showed phenotypes very similar to the previous embryonic stem (ES)-cell-based KO mice, they differed from the previous reports in that a reduction in body weight was observed in males. These results demonstrate that these newly established Tff1-KO mice are useful tools for investigating genetic and environmental factors influencing gastric cancer, without the effects of artificial gene insertion. Furthermore, these findings suggest a novel hypothesis that Tff1 expression influences gender differences.

• 대한토목학회논문집
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• 제41권3호
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• pp.209-217
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• 2021

산불은 대부분 인위적인 원인에 의해 발생되지만, 산불의 피해가 대규모로 확산하는 연소 조건은 자연현상에 의해 영향을 받게 된다. 본 연구에서는 여러 인자 사이의 의존 및 인과관계를 분석할 수 있는 부분최소제곱 구조방정식 모형(PLS-SEM)을 이용하여 기상 및 가뭄이 산불 발생에 미치는 인과관계와 영향 정도를 평가하였다. 그 결과 지난 2015년부터 약 5년 기간 동안 발생한 강원도 산불에 미치는 가뭄의 영향은 27 %, 기상학적 영향은 38 %로 확인되었다. 또한, 강원도에서 발생한 산불 중에서 봄철에 발생한 산불은 약 60 %의 비율을 차지하며, 이는 기상학적 요인과 더불어 이전 연도의 가을과 겨울철 가뭄이 산불 발생에 영향을 미치는 것으로 해석된다. 산불 발생위험을 평가하는 데 있어 극심한 기상학적 가뭄이 가을과 겨울철에 발생했다면, 이듬해 봄에는 산불의 발생확률은 증가할 가능성이 있다.

• 한국의류학회지
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• 제46권1호
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• pp.80-98
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• 2022

Artificial intelligent chatbot services have recently become common in fashion e-retailing and are expected to improve online shopping by making it easy to recommend products. This study examines whether the perceived quality of a fashion chatbot affects consumers' trust and perception of usefulness, which in turn influences satisfaction and intention to use, in accordance with the information system success model. The study also investigates differences in perceived quality and consumer response variables between high and low groups of self-efficacy. A total of 341 consumers participated in an online survey. The results revealed that information quality and system quality had a significant impact on perceived usefulness and trust, and that service quality significantly impacted trust. Perceived usefulness and trust had a positive effect on consumer satisfaction, which in turn had a positive effect on intention to use. In addition, the findings revealed that people who had higher self-efficacy showed higher scores on perceived usefulness, trust, satisfaction, and intention to use chatbots as compared to people who had lower self-efficacy. This study suggested theoretical implications by applying the information system success model theory to fashion chatbot studies. It also suggested practical implications for e-commerce marketers developing retail strategies.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.35-37
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• 2021

외래 관광객 수요를 분석하고 예측하는 것은 관광 정책을 수립하고 기획하는데 지대한 영향을 미치기 때문에 관광 산업 분야에서 매우 중요하다. 외래 관광객 데이터는 여러 외적 요인들에 의해 영향을 받기 때문에, 시간에 따른 미세한 변화가 많다는 특징을 갖는다. 따라서, 최근에는 관광객 입국자 수요를 예측하기 위해 경제 변수 등 여러 외적 요인들도 함께 반영하여 예측 모델을 설계하는 연구를 진행하고 있다. 그러나 기존의 시계열 예측에 주로 사용되는 회귀분석 모델과 순환신경망 모델은 여러 변수들을 반영하는 시계열 예측에 있어 좋은 성능을 보이지 못했다. 따라서 우리는 합성곱 신경망을 활용하여 이러한 한계점들을 보완한 외래 관광객 수요 예측 모델을 소개한다. 본 논문에서는 한국관광공사에서 제공한 과거 10개년 외래 관광객 데이터와 추가적으로 수집한 여러 외적 요인들을 입력 변수로 반영하는 1차원 합성곱 신경망을 설계하여 외래 관광객 수요를 예측하는 모델을 제시한다.

• 한국지반공학회논문집
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• 제39권11호
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• pp.41-51
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• 2023

설치 경사각도에 따른 삼축내진말뚝의 동적 거동 특성을 파악하기 위해 3차원 수치해석을 수행하였다. FLAC3D를 통해 3차원 수치모델을 구축하였으며, 동적 원심모형실험과의 비교를 통해 검증하였다. 수치해석 결과, 경사각도에 따라 말뚝의 동적 거동이 확연히 달라짐을 확인하였다. 실지진파 조건(Capetown EQ, San Fernando EQ)에서는 경사각도가 15도 일 때, 다른 경사각도(0도, 30도)에 비해 말뚝의 휨모멘트 및 침하량이 적음을 알 수 있었다. 반면 인공지진파 조건(Sine 2Hz EQ)에 대해서는 경사각도가 0도 일 때 가장 적은 부재력(휨모멘트, 축력) 및 침하량을 보여 지진파의 특성에 따라 동적 거동이 달라짐을 확인하였다.

• 한국환경농학회지
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• 제42권4호
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• pp.279-285
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• 2023

The demand for the fresh leaf of hooker chive, which is mainly used as functional roots and contains dietary sulfur or saponin, is increasing, but the leaves are only harvested 3-4 times per year under conventional field conditions. A plant factory system with different light qualities or intensities was applied for year-round production of the fresh leaves. Hooker chive (Allium hookeri) roots were hydroponically cultured under the plant factory with a mixture of blue plus red LEDs (Light-Emitting Diodes) and fluorescent lights for 50 weeks. Maximum leaf growth was attained with the 1.5 dS/m EC in the culture medium under the plant factory. The average leaf and shoot numbers of hooker chive grown hydroponically under a mixture of 200 µmol/m²/s LEDs increased by 147% and 140%, respectively compared to those under 100 µmol/m²/s LEDs at the 10th harvest. The leaf length of hooker chive grown under the LEDs treatment with the lowest light intensity significantly increased by 27% compared with the natural light treatment at the 10th harvest. However, there was no significant difference in leaf pigmentation between natural and 200 µmol/m²/s LEDs treatments. Plant factory with the mixture LEDs of blue and red lights can be applied for year-round production of hooker chive fresh leaves to ensure a stable supply of leafy vegetable throughout the year.