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김구배,이창완 전북대학교 산업경제연구소 2000 전북대학교 산업경제연구소 논문집 Vol.31 No.-
국내에서 이루어진 재무분석가의 이익 예측치의 예측정확성에 관한 연구는 재무분석가의 예측치가 시계열 모형의 예측치보다 예측의 정확성이 높다는 연구와 차이가 없다는 연구로 특징 지 울 수 있다. 이러한 상반된 연구결과는 표본의 수량 및 표본기간의 선정에서의 편의 그리고 재무분석가의 대표성에서 그 원인을 찾을 수 있다. 따라서, 본 연구는 최근의 자료(1996-1998)를 중심으로 표본을 선정하고 개선된 연구설계에 의하여 이익 예측시점을 통제한 상태에서 다수 재무분석가의 예측치를 이용하여 재무분석가와 시계열 모형 그리고 재무분석가간의 상대적 예측 정확성을 검증하고 시장기대이익의 적절한 대용치의 선정에 유용한 지표를 제공하는데 있다. 분석 결과 첫째, 재무분석가는 과대 예측하는 경향이 있다. 둘째, 재무분석가간(대우증권, 쌍용증권, 동원증권, LG증권) 그리고 재무분석가와 RW 모형간 예측 정확성을 검증한 결과 유의한 차이는 나타나지 않았다. 셋째, 재무분석가의 예측치는 결산 월에 가까워 질 수록 예측의 정확성이 높아졌다
지동윤,이창완,박세희,이은직,이도엽 사단법인 한국질량분석학회 2017 Mass spectrometry letters Vol.8 No.4
Single analytical procedure including extraction, liquid chromatography, and mass spectrometric analysis was evaluated for the simultaneous measurement of lysophospholipids (LPLs). LPLs, particularly, lysophosphatidic acids (LPA) and sphingosine 1-phosphate (S1P) are lipid messengers ubiquitously found in various biological matrix. The molecular species mediate important physiological roles in association with many diseases (e.g. cancer, inflammation, and neurodegenerative disease), which emphasize the significance of the simple and reliable analytical method for biomarker discovery and molecular mechanistic understanding. Thus, we developed analytical method mainly focusing on, but not limited by those lipid species S1P and LPA using reverse phase liquid chromatography-tandem mass spectrometry (RPLC-ESI-MS-MS). Extraction method was modified based on Folch method with optimally minimal level of ionization additive (ammonium formate 10 mM and formic acid). Reverse-phase liquid-chromatography was applied for chromatographical separation in combination with negative ionization mode electrospray-coupled Orbitrap mass spectrometry. The method validation was performed on human blood plasma in a non-targeted lipid profiling manner with full-scan MS mode and data-dependent MS/MS. The proposed method presented good inter-assay precision for primary targets, S1P and LPA. Subsequent analysis of other types of LPLs identified a broad range of lysophosphatidylcholines (LPCs) and lysophosphatidyl-ethanolamines (LPEs).
지르코니아-유리복합체용 글래스의 조성에서 MgO의 함량 변화가 강도에 미치는 영향
이규선,이창완,이채현,Lee, Kyu-Sun,Lee, Chang-Wan,Lee, Chae-Hyun 대한치과기공학회 2007 대한치과기공학회지 Vol.29 No.1
The quantity of MgO in the Zirconia of 20wt% Frit has been varied and the sintering temperature has been differentiated to monitor the changes in the mechanical features. The rise of sintering temperature from 1100$^{\circ}C$ to 1300$^{\circ}C$ was followed by higher sintering density. And, at a sintering temperature, the increase of the quantity of MgO was followed by lower sintering density. The bending strength has been lowered as the quantity of MgO increases in the Zirconia of 20wt% Frit, which seems to be because the MgO functions as impurities degrading the mechanical features. In terms of micro-structure analysis, the pore has been greatly enlarged, while the density varied very little, when the MgO of 3wt% was added. The size of pore became smaller as the added quantity of MgO increased larger in the sequence of 5wt% and 7wt%. But, the pore-generating rate became higher as the added quantity of MgO increased in the sequence of 3wt%, 5wt% and 7wt%. Thus, it is possible to summarize that the small quantity of MgO, say, of 3wt%, promotes the grain growth, and the large quantity of MgO, say, of 7wt%, hinders the grain growth. Also, if the quantity of MgO exceeds some level, the MgO hinders substances from moving, which, ultimately, keeps blowholes from becoming enlarged or extinct, and makes pores small and dispersed in broad area. In conclusion, the study on the change in the size of pore shows that the larger the quantity of MgO is, the more the micro pores are, thereby degrading the mechanical features.
신규 화장품 소재로서 Lactobacillus plantarum HDB1234 용암해수 발효물의 피부장벽강화 효과
양서진 ( Seo-jin Yang ),이창완 ( Chang-wan Lee ),차소윤 ( So Yoon Cha ),최지휘 ( Ji-whi Choi ),이승훈 ( Seunghun Lee ) 한국미용학회 2021 한국미용학회지 Vol.27 No.2
In this study, we developed Lava-Dermabiotics HDB1234 using Lactobacillus plantarum HDB1234 and lava seawater fermentation technology to enhance skin barrier. The use of lava seawater increased the purity and concentration of nucleotides in Lava-Dermabiotics HDB1234 by using nanodrop 2000 spectrophotometer. Also, when 5%(v/v) Lava-Dermabiotics HDB1234 was treated, cytotoxicity on normal human epidermal keratinocytes (NHEKs) and human fibroblast cells was not observed by using MTT assay. The mRNA expressions of claudin-1 (CLDN-1), serine palmitoyltransferase (SPT), and filaggrin (FLG) on Lava-Dermabiotics HDB1234 treated cells were dose-dependent higher than those of non-treated cells. Especially, the protein expression of FLG was also confirmed by using western blotting and immunocytochemistry staining. These results indicated that Lava-Dermabiotics HDB1234 could be used as a potential cosmetic ingredient for skin barrier enhancement through CLDN-1, SPT, and FLG expression related to the formation of skin barrier.
솔-젤법에 의해 제조된 실리콘 태양전지 전극형성용 나노 글래스
강성구(Seong Gu Kang),이창완(Chang Wan Lee),정윤장(Yoon Jang Chung),김창균(Chang-Gyoun Kim),김성탁(Seongtak Kim),김동환(Donghwan Kim),이영국(Young Kuk Lee) 한국태양광발전학회 2014 Current Photovoltaic Research Vol.2 No.4
We have investigated the seed layer formation of front side contact using the inkjet printing process. Conductive silver ink was printed on textured Si wafers with 80 nm thick SiNx anti reflection coating (ARC) layers and thickened by light induced plating (LIP). The inkjet printable sliver inks were specifically formulated for inkjet printing on these substrates. Also, a novel method to prepare nano-sized glass frits by the sol-gel process with particle sizes around 5 nm is presented. Furthermore, dispersion stability of the formulated ink was measured using a Turbiscan. By implementing these glass frits, it was found that a continuous and uniform seed layer with a line width of 40㎛ could be formed by a inkjet printing process. We also investigated the contact resistance between the front contact and emitter using the transfer length model (TLM). On an emitter with the sheet resistance of 60 Ω/sq, a specific contact resistance (pc) below 10 mΩ · cm² could be achieved at a peak firing temperature around 700 °C. In addition, the correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy (SEM). We found that the added glass particles act as a very effective fire through agent, and Ag crystallites are formed along the interface glass layer.
자동차용 휠 베어링 시일의 설계를 위한 시일 립 변형해석
김헌영(Heonyoung Kim),문형일(Hyungil Moon),이창완(Changwan Lee),임종순(Jongsoon Lim),박지헌(Jihun Park),김영태(Youngtae Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Designing technology of bearing seal is closely connected with the efficiency and durability of whole bearing. So, if the efficiency of bearing seal is estimated and this estimation is used to the design, then we can produce the bearing seal that have better efficiency and durability The efficiency of bearing seal is strongly dependent on the shape of bearing seal lip. So if the designing factors of seal lip are determined, then optimized design of bearing seal can be conducted more efficiently. This study describes all the matters required for analysis using F.E.M. which is one of the methods for finding optimized design factors. The contents has been made up with the emphasis on seal lip modeling method and analysis process.