• 한국재료학회지
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• 제31권9호
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• pp.525-531
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• 2021

Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO₂ methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO₂ methanation reaction. Ni@5C that is produced under 5 % CH₄ partial pressure in Ar gas has highest conversions of 68 % at 350 ℃ and 70 % at 400 ℃, which are 73 and 75 % of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO₂ methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

• Journal of Applied Biological Chemistry
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• 제64권4호
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• pp.375-382
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• 2021

조록나무는 제주도 및 일본 혼슈 이남, 중국 동남부, 타이완 등에 분포하는 조록나무과의 상록 교목으로, 항산화 및 tyrosinase, elastase의 억제에 효과적인 것으로 알려져 있지만 NO에 대한 억제 효능은 미미한 것으로 보고되었다. 이에 본 연구는 조록나무 잎 추출물(DL)에 biorenovation 생물 전환 기법을 적용하여 항 염증 활성을 증진 시키고자 수행되었다. 이들의 활성은 LPS로 자극된 RAW264.7 염증 모델에서 평가 되었으며 NO, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) 및 전 염증성 사이토카인에 대한 억제 실험이 수행되었다. 그 결과, biorenovation을 적용한 조록나무 잎 추출물(DLB)는 독성이 없는 농도에서 DL대비 향상된 NO와 prostaglandin E2 억제효능을 나타내었으며, 이들의 합성 효소인 iNOS 및 COX-2의 발현에도 유의한 억제 경향을 나타내었다. 또한 대표적인 전 염증성 사이토 카인인 tumor necrosis factor-α, Interleukin 6, Interleukin-1β 에서도 향상된 억제 효능을 확인 하였다. 이러한 결과를 근거로 우리는 biorenovation을 통해 DL의 항염증 효능이 개선될 수 있으며, DLB가 효과적인 천연 항염증 소재로 적용될 수 있음을 제시한다.

• 융합정보논문지
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• 제11권7호
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• pp.91-103
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• 2021

지식경영이 조직의 중요한 역량으로 인식되면서, 조직들은 지식경영 정책, 기술 등에 지속적으로 투자를 하고 있다. 지식경영은 조직원의 핵심 지식에 대한 공유가 선제적으로 요구되나, 지속적인 지식경영 활동을 위한 공유 활동이 이루어지지 못하고 있다. 본 연구의 목적은 조직의 협력적 커뮤니케이션을 통한 상호 교환 노력이 구성원의 지식공유 의도에 미치는 영향을 검증하는 것이다. 연구는 지식경영 정책을 도입한 조직의 근로자들을 대상으로 설문을 하였으며, 326개의 표본을 구조방정식모델링에 적용하여 연구 가설을 검증하였다. 분석 결과, 협력적 커뮤니케이션 구성 요인(합리성, 상호 피드백, 공식성)이 지식공유 의도에 긍정적 영향을 주었으며, 업무 상호의존성과 지식 영역성이 협력적 커뮤니케이션과 지식공유 의도 간의 관계를 조절하였다. 연구는 구성원의 지식공유 향상을 위해 조직이 추진해야 할 활동 전략을 제시하였다는 측면에서 시사점을 가진다.

• 기록학연구
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• 제9호
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• pp.110-142
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• 2004

This paper treated what are congressional records which are one of core fields of national records and what kind of significant records they have. The characteristics of "substantive records" of the institution among public records are as follows: firstly, their contents depend on the inherent function of the institution; secondly, their types differ by the character of basic unit(member); thirdly, their sources are determined by the character of institution. Starting from the above points of view, the contents, characteristics, main sources, and types by sources of congressional records were presented. They are summarized as follows. In Chapter 2, the substantial records, which document the intrinsic function of congress on the basis of analyses of inherent function and structural uniqueness of congress have natures of which the contents are "legislative records", "oversight records", and "political activity records" starting from the inherency of congress as the people's representation. The typical natures of congress records are related with the specialty that the basic unit of congress structure is an individual congressman as an indepent national institution and congress is a council of these congressmen. Firstly, the records of congressmen as basic member of congress are the national records with the type of personal records. Secondly, "council records" produced by the council (commettee and main conference), which have evidencial and informative value for decision making through the process of investigating, discussing and voting bill and policy (item) of the basis for national management, are very special kind of records, such as item records, decision records, journal records, and congress assistant records. Because congressmen and councils composing congress have an equal inter-relationship in the structure of congress, the main sources of congress records are an individual congressman and all the councils. In chapter 3, the contents and sorts of main records are discribed, centering around congressmen and councils as the main sources of congress records. In chapter 4, the management of records of congressmen is issued as an urgent subject for the management of congress records, instead of conclusions.

• 한국치위생학회지
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• 제18권6호
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• pp.1025-1035
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• 2018

Objectives: This study examined dental hygiene students' frequency of participation in community volunteer activities, job consciousness, depression, and self-esteem, and then identified the correlation among them. We also analyzed the moderating effect of depression and self-esteem on the correlation between participation in community volunteer activities and job consciousness. Methods: We surveyed 312 dental hygiene students attending four universities in South Chungcheong Province, Korea, from May 2 to June 15, 2016, through direct visits. They were given structured questionnaires containing four items on community volunteer activities, three on job consciousness, ten on self-esteem, and 13 on depression. To examine the moderating effect of depression and self-esteem, we performed analysis of variance, correlation analysis, and structural equation modeling analysis (based on the path analysis model and by inserting interaction terms) using SPSS and AMOS. Results: We observed a negative correlation between self-esteem and depression (r=-0.062) but a positive correlation between self-esteem and job consciousness (r=0.125). Depression and job consciousness had a negative correlation (r=-0.176). Depression had a statistically significant impact on job consciousness (r=-0.519, p<0.01). The interaction term between depression and frequency of community volunteer activities also had a statistically significant influence on job consciousness (r=0.090, p<0.05). These findings indicate that depression moderates the correlation between frequency of community volunteer activities and job consciousness at a statistically significant level. Conclusions: More frequent participation in volunteer activities enhances dental hygiene students' self-esteem, reduces depression, and raises job consciousness. The positive impact of volunteering on self-esteem, depression, and job consciousness warrants encouraging students' participation in community volunteer activities, creating supportive structures, and developing various volunteer programs relevant to the students' area of study.

• 한국건설관리학회논문집
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• 제20권4호
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• pp.94-103
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• 2019

건설프로젝트의 품질경영활동에서 조직구성원의 적극적인 참여는 성공적인 경영성과 달성을 촉진한다. 본 연구는 참여를 촉진하는 메커니즘을 발견하고자 한다. 선행연구에서 참여를 촉진하는 선행요인은 보상시스템과 만족이다. 제안된 연구모델의 검증을 위해 232명을 대상으로 샘플데이터를 수집했다. 구조방정식 모델을 이용한 실증분석을 했다. 연구 결과, 제안된 모든 변수가 직원참여에 유의한 정(+)의 영향을 미쳤다. 직급 및 근로계약 유형에 따른 조절효과가 발휘되었다. 본 연구의 결과는 품질경영활동의 촉진을 위한 보다 폭넓은 관점에서 참여를 촉진할 방안을 모색하는 연구자 및 관리자에게 유용한 이론 및 실무적 시사점을 제공할 것으로 기대한다.

• 재활복지
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• 제21권2호
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• pp.139-167
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• 2017

본 연구의 목적은 장애인 가구의 소득과 소비지출 수준에 따라 생활만족도 간 어떠한 영향관계가 있는지 알아보고, 이들의 영향관계에서 사회 경제적 지위가 매개역할을 하는지를 파악하는 것이다. 연구의 목적을 달성하기 위해 장애인고용패널 8차 자료를 활용 하였으며, 결론은 다음과 같다. 첫째, 가구소득은 엥겔계수와 슈바베지수에 부적(-)영향, 사회 경제적 지위와 생활만족도에는 정적(+)영향을 주었다. 또한, 엥겔계수는 사회 경제적 지위에는 부적(-)영향, 생활만족도에는 정적(+)영향을 주었고, 슈바베지수는 사회 경제적 지위에 부적(-)영향을 주었지만, 생활만족도에는 영향을 주지 못했으며 사회경제적지위는 생활만족도에 정적(+)영향을 주었다. 한편, 사회 경제적 지위는 가구소득과 생활만족도, 엥겔계수와 생활만족도 간 경로에서는 부분매개를, 슈바베지수와 생활만족도 간 경로에서는 완전매개역할을 하는 것으로 나타났다. 이상의 연구결과를 토대로 장애인의 생활만족도에 있어 주관적 계층의식을 나타내는 사회 경제적 지위의 역할과 중요성 그리고 소득보장을 위한 경제활동의 필요성을 강조하였으며 이를 위해 필요한 정책적 방향을 논의하였다.

• 마이크로전자및패키징학회지
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• 제26권1호
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• pp.23-28
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• 2019

타이타니아 ($TiO_2$)는 독성이 없고 매우 높은 굴절률, 촉매 활성 및 생체 적합성을 지니고 있으며 화학적 안정성이 있고 높은 이방성을 갖는 저렴한 재료로써 다양한 분야에서 각광받고 있는 세라믹 소재이다. 이러한 $TiO_2$를 sol-gel법을 이용하여 나노입자화 하였다. 나노입자 형성중에 pH를 조절하여 $TiO_2$의 결정성을 제어하였다. 합성된 나노입자는 엑스선 회절분석법, 퓨리에 분광기(Fourier transform infrared), 전계방사형 주사전자현미경(field emission scanning electron microscopy)과 포토루미네선스(photoluminescence spectroscopy)를 이용하여 분석하였다. 합성된 $TiO_2$ 나노입자는 5 nm 이하의 크기를 갖는 것을 확인하였다. 나노입자의 결정성이 증가됨에 따라 550 nm 영역의 발광세기가 증가함을 확인하였다. 이러한 결과로 $TiO_2$ 나노입자의 결정성 조절을 통한 발광 특성 조절을 기대할 수 있다.

• Endocrinology and Metabolism
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• 제33권4호
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• pp.485-492
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• 2018

Background: Increasing evidence supports interplay between aldosterone and parathyroid hormone (PTH), which may aggravate cardiovascular complications in various heart diseases. Negative structural cardiovascular remodeling by primary aldosteronism (PA) is also suspected to be associated with changes in calcium levels. However, to date, few clinical studies have examined how changes in calcium and PTH levels influence cardiovascular outcomes in PA patients. Therefore, we investigated the impact of altered calcium homeostasis caused by excessive aldosterone on cardiovascular parameters in patients with PA. Methods: Forty-two patients (mean age $48.8{\pm}10.9$ years; 1:1, male:female) whose plasma aldosterone concentration/plasma renin activity ratio was more than 30 were selected among those who had visited Severance Hospital from 2010 to 2014. All patients underwent adrenal venous sampling with complete access to both adrenal veins. Results: The prevalence of unilateral adrenal adenoma (54.8%) was similar to that of bilateral adrenal hyperplasia. Mean serum corrected calcium level was $8.9{\pm}0.3mg/dL$ (range, 8.3 to 9.9). The corrected calcium level had a negative linear correlation with left ventricular end-diastolic diameter (LVEDD, ${\rho}=-0.424$, P=0.031). Moreover, multivariable regression analysis showed that the corrected calcium level was marginally associated with the LVEDD and corrected QT (QTc) interval (${\beta}=-0.366$, P=0.068 and ${\beta}=-0.252$, P=0.070, respectively). Conclusion: Aldosterone-mediated hypercalciuria and subsequent hypocalcemia may be partly involved in the development of cardiac remodeling as well as a prolonged QTc interval, in subjects with PA, thereby triggering deleterious effects on target organs additively.

• Journal of Ginseng Research
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• 제43권4호
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• pp.539-549
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• 2019

Background: 20(S)-Protopanaxadiol (PPD), the aglycone part of 20(S)-protopanaxadiol ginsenosides, possesses antidepressant activity among many other pharmacological activities. It is currently undergoing clinical trial in China as an antidepressant. Methods: In this study, an ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass tandem mass spectrometry method was established to identify the metabolites of PPD in human plasma and urine following oral administration in phase IIa clinical trial. Results: A total of 40 metabolites in human plasma and urine were identified using this method. Four metabolites identified were isolated from rat feces, and two of them were analyzed by NMR to elucidate the exact structures. The structures of isolated compounds were confirmed as (20S,24S)-epoxydammarane-12,23,25-triol-3-one and (20S,24S)-epoxydammarane-3,12,23,25-tetrol. Both compounds were found as metabolites in human for the first time. Upon comparing our findings with the findings of the in vitro study of PPD metabolism in human liver microsomes and human hepatocytes, metabolites with m/z 475.3783 and phase II metabolites were not found in our study whereas metabolites with m/z 505.3530, 523.3641, and 525.3788 were exclusively detected in our experiments. Conclusion: The metabolites identified using ultra-performance liquid chromatography coupled with triple quadrupole time-of-flight mass spectrometry in our study were mostly hydroxylated metabolites. This indicated that PPD was metabolized in human body mainly through phase I hepatic metabolism. The main metabolites are in 20,24-oxide form with multiple hydroxylation sites. Finally, the metabolic pathways of PPD in vivo (human) were proposed based on structural analysis.