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      • 1.0.$\mu$ CMOS SOG로 구현한 직접 디지털 주파수합성기의 성능에 관한 고찰

        김대용,이종선 대한전자공학회 1997 電子工學會論文誌, D Vol.d34 No.3

        In this study, two types of the direct digital frequency synthesizers (DDFS) designed and implemented using 1.0.mu.m CMOS gatearray(SOG) technolgoies are interoduced. To analize the effect of the number of phase bits(L), address data bits(A), and DAC bits (D) on the output spectrums of the DDFSs, the NCO-based BCD-DDFS composed of L=24, A=14, and D=8, and the improved binary-DDFS composed of L=24, A=8, and D=10 have been studied. The chips have been designed with and without a noise shapper to reduce spurious noises due to phase truncation and reduced sine ROM in output spectrum.

      • KCI등재

        조선후기 교육의 변화와 향촌사회

        김대용 대구사학회 2001 대구사학 Vol.64 No.1

        This study is to examine the relation between the change in Education and the rural communities in the late Chosun. The education in Chosun was very important in a nation and an individual. In a national point of view, the education has been two meanings. That is, one was cultivating the virtues of the ruled people, the other was the instruments which fostered the ruling class internalizing dominant ideology. In an individual dimension, the education was the means of status maintenance or status upgrading. When education was related to status maintenance or status upgrading, the other status groups as well as local gentry could not help taking much interests in education. Especially, education was greatly changed in late Choson when the development of productive force and commercial monetary economy appeared. The state could not but acknowledge the influence of the local gentry because of financial difficulties and the crisis of feudalistic regime in the sixteenth century. The establishment of Seowon was to strengthen the influence of the local gentry in the rural communities. The local gentry established Yuhyangso, Hyangyak etc. esides Seowon, and these complemented each other. With the progress of the factional strife, Seowon became to take the strong political characteristics in that it was a point of contact between central political circles and the local gentry. It facilitated the evils of Seowon, and it became to be necessary for state to control Seowon in result. The state control to Seowon was connected with the policy that would recover the educational initiative of state or local magistrates in the rural communities. As the result, the system of the schoolmaster of a subcountry in the late seventeenth century and Yangsajae in the eighteenth century were established in nearly all the country. As the production force and commercial monetary economy developed, the illegitiamates, the local government functionaries that had been ascending status in a steady curve established organs of education, or demanded to participate in the management of Seowon that the local gentry established. The rich commoners also put their names on Hyanggyo and Seowon register and established Seodang of their own to pursue to upgrade their status. As above, the education in the late Chosun was closely related to the ruling structure in the rural communities, the change in interrelationship among the social forces, and the collapse of status system.

      • SCOPUSSCIEKCI등재

        성상세포종에서의 p27<sup>kip1</sup> 단백의 발현

        김대용,손현진,정명자,강명재,Kim,,Dae,Yong,Son,,Hyun,Jin,Chung,,Myoung,Ja,Kang,,Myoung,Jae 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.4

        Objective : The cyclin-dependent kinase inhibitor $p27^{kip1}$ protein is a negative regulator of the cell cycle, and its degradation is required for entry into the S phase. Loss of $p27^{kip1}$ expression has been reported to be associated with aggressive behavior in a variety of tumors of epithelial and lymphoid origin. However, its association with various astrocytic tumors has not been clearly demonstrated. We studied to investigate the relationship of $p27^{kip1}$ expression with the biological behavior of astrocytic tumors in addition to study on the role of $p27^{kip1}$ in the tumorigenesis of these tumors. Patients and Methods : From 1990 to 1998, a total of 29 astrocytic tumor of all grades obtained by operative resection were included for evaluation. We studied the expression of $p27^{kip1}$ protein immunohistochemical assay in astrocytic tumors and compared the findings with the clinicopathologic parameters. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded sections by the avidin-biotin-peroxidase complex method. According to WHO classification, all cases were divided into astrocytomas(4 cases), anaplastic astrocytomas(9 cases), and glioblastomas(16 cases) by 3 pathologists. Clinical information was obtained from medical records, and others such as location and size of tumors from imaging studies. Results : Mean $p27^{kip1}$ protein labeling indexes(LI, mean${\pm}$standard deviation) of astrocytomas, anaplastic astrocytomas, and glioblastomas were $80.6{\pm}9.1$, $63.6{\pm}21.0$, and $28.9{\pm}18.7$, respectively, and were inversely correlated with grade of glial tumors(p<0.0001). Mean $p27^{kip1}$ protein LI in the recurrent group was lower than that in the nonrecurrent group, but there was no significant difference statistically(p=0.464). Additionally, $p27^{kip1}$ protein expression did not show any significant relationship to other prognostic factors such as age(p=0.1643), tumor size(p=0.8), or location(p=0.8). Conclusion : These results suggested that reduced expression of $p27^{kip1}$ protein may play a important role in the malignant transformation process of astrocytic tumor cells.

      • KCI등재
      • KCI등재후보SCOPUS
      • KCI등재

        칼라영상을 이용한 방울토마토 품질 인자 계측에 관한 연구

        김대용,오현근,이남근,김영식,조병관 충남대학교 농업과학연구소 2010 농업과학연구 Vol.37 No.2

        Surface color is the most important quality factor for the grade evaluation of cherry tomato. Color is one of the representative indicators for the maturity which is closely related to the internal quality of cherry tomato, such as firmness, sugar content, and acidity. This study was carried out to investigate the relationship between surface color and internal quality of cherry tomatoes harvested from both hydroponic and soil culture at different ripening stages . To calculate the color values of cherry tomatoes an automatic color imaging system was constructed. A specially designed image processing algorithm for the color measurement was developed. The color values of L*, a*, b* were calculated from the initial color values of RGB and then compared with the internal quality. Statistical analyses indicated that the internal quality was more highly correlated with the surface color than size of cherry tomatoes. Color image features were also investigated to detect external damage of cherry tomatoes. The value of (R value - R mean value)/R mean value was the most effective image feature for the detection of damaged areas on the surface of cherry tomatoes. The results of this study demonstrated the feasibility of color sorting process as an alternative of the conventional drum type size sorting system for cherry tomato industry.

      • KCI등재

        상품공간 구조의 동태적 변화에 관한 연구

        김대용 통계청 2018 통계연구 Vol.23 No.2

        본 연구는 경제학 관점에서 상품공간의 이론적 배경 및 전개를 살펴보았고, 네트워크 관점에서 상품공간 모형을 재해석하는 한편, 상품공간 구조의 동태적 변화에 대한 실증분석을 실시하였다. 특히 상품공간에서의 산업 구조변화를 살펴보기 위해 상품근접성 및 상품경로의 분포가 전체 또는 산업별로 동태적 변화를 보여 왔는가에 대한 실증분석을 실시하였다. 분석결과, 선진국형(기술집약적, 인적자본집약적) 산업이 중심부를 이루고, 후진국형(기초재화나 천연자원집약적) 산업이 주변부를 이루었다. 이는 신상품 개발에 따른 인센티브를 나타내는 상품 간의 거리는 끊임없이 변하면서 동태적 산업구조 변화를 이끌어 가고 있는 반면, 중심-주변부 간의 구조적 양극화 문제는 지속되어 왔다는 사실을 알 수 있었다. 상품공간은 미시적인 측면에서 상호 연결관계가 복잡하고 진화를 거듭하고 있지만 거시적 측면에서 중심-주변부 구조나 형태가 유지되고 있는 특징을 나타냈다. 이러한 특징은 좁은 세상이나 척도없는 네트워크 모형과 밀접하게 연관된다. This paper aims to examine a product space in terms of economics and complex network, including its theoretical background, usefulness and empirical findings in product space. Especially, this paper analyze how the empirical distribution of the proximity and paths, which is sorted by the factor intensity-driven industry group, dynamically changes over time in terms of structural transformation in product space. The empirical findings shows that, in product space, the products in more sophisticated industries, i.e. technology intensive and human-capital intensive industries, are located in a densely connected core, otherwise other products in less sophisticated industries (primary and natural-resource intensive industries) occupy a less-connected periphery. In addition, this findings supports the empirical evidence on dynamics of structure in product space, which defined as the continuous structural transformation in micro level and persistence of the core-periphery structure of the product space in macro level. In terms of network theory and terminology, this findings shows that the product space is closely related to characteristics of small-world or scale-free network.

      • KCI등재SCOPUS

        Long-Term Efficacy of Endoscopic Submucosal Dissection Compared with Surgery for Early Gastric Cancer: A Retrospective Cohort Study

        김대용,홍수진,조규석,정귀애,김희경,한재필,이윤나,고봉민,이문성 거트앤리버 소화기연관학회협의회 2014 Gut and Liver Vol.8 No.5

        Background/Aims: This study aimed to compare the outcomesof endoscopic submucosal dissection (ESD) andgastrectomy based on the two sets of indications for ESD,namely guideline criteria (GC) and expanded criteria (EC). Methods: Between January 2004 and July 2007, 213 earlygastric cancer (EGC) patients were enrolled in this study. Of these patients, 142 underwent ESD, and 71 underwentgastrectomy. We evaluated the clinical outcomes of thesepatients according to the criteria. Results: The complicationrates in the ESD and gastrectomy groups were 8.5% and28.2%, respectively. The duration of hospital stay was significantlyshorter in the ESD group than the gastrectomy groupaccording to the GC and EC (p<0.001 and p<0.001, respectively). There was no recurrence in the ESD and gastrectomygroups according to the GC, and the recurrence rates in theESD and gastrectomy groups were 4.7% and 0.0% accordingto the EC, respectively (p=0.279). The occurrence rates ofmetachronous cancer in the ESD and gastrectomy groupswere 5.7% and 5.0% according to the GC (p=1.000) and7.5% and 0.0% according to the EC (p=0.055), respectively. Conclusions: Based on safety, duration of hospital stay, andlong-term outcomes, ESD may be an effective and safe firstlinetreatment for EGC according to the EC and GC.

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