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An Efficient Buffer Page Replacement Strategy for System Software on Flash Memory (플래시 메모리상에서 시스템 소프트웨어의 효율적인 버퍼 페이지 교체 기법)

  • Park, Jong-Min;Park, Dong-Joo
    • Journal of KIISE:Databases
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    • v.34 no.2
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    • pp.133-140
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    • 2007
  • Flash memory has penetrated our life in various forms. For example, flash memory is important storage component of ubiquitous computing or mobile products such as cell phone, MP3 player, PDA, and portable storage kits. Behind of the wide acceptance as memory is many advantages of flash memory: for instances, low power consumption, nonvolatile, stability and portability. In addition to mentioned strengths, the recent development of gigabyte range capacity flash memory makes a careful prediction that the flash memory might replace some of storage area dominated by hard disks. In order to have overwriting function, one block must be erased before overwriting is performed. This difference results in the cost of reading, writing and erasing in flash memory[1][5][6]. Since this difference has not been considered in traditional buffer replacement technologies adopted in system software such as OS and DBMS, a new buffer replacement strategy becomes necessary. In this paper, a new buffer replacement strategy, reflecting difference I/O cost and applicable to flash memory, suggest and compares with other buffer replacement strategies using workloads as Zipfian distribution and real data.

Case Study on Decision-Making Process for M&A in Small and Medium Companies (중소기업 M&A 의사결정 과정에 관한 연구)

  • Jung, Han-Seok;Moon, Jae-Seung
    • Journal of Distribution Science
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    • v.13 no.10
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    • pp.65-72
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    • 2015
  • Purpose - A rapidly changing business environment places great demands on small and medium-sized enterprises (SMEs). These SMEs need to find strategic alternatives for continued growth and, ultimately, survival. Thus, mergers and acquisitions (M&A) are deemed an acceptable solution. Research to date has dealt with M&A in major organizations and focused on post merger integration (PMI). Our study focuses on SMEs, as they are relatively new and unknown to the public. Therefore, this study highlights successful M&A and decision making for SMEs through a case study analysis. Research design, data, and methodology - For this study, we examined an M&A case between company S, which produces cell phone parts, and company P, which produces SSD cases. We reviewed theories and previous studies in M&A literature. We comprehensively examined the decision-making procedure at each M&A stage, describing the situation of the buying company and the selling company from the period of the M&A announcement through deal completion. In addition, we conducted interviews with both companies. The data regarding this case study were collected through interviews with managers of both companies who actively participated in the M&A process. When necessary, we asked them about additional relevant information during the interviews. Results - The result of the M&A between company S and company P was deemed acceptable with the exception of the long negotiation period. However, company S was not able to prepare for PMI after the acquisition due to a controversy over acquisition values. Moreover, the employees of the newly formed company, especially those who came from company P, complained about the M&A and attempted to leave. Thus, implications for successful M&As of SMEs are as follows: First, the procedural compliance of the M&A is needed. Second, support is needed from the CEO for the working group, rather than excessive intervention during due diligence. Third, the right, talented members of the organization should be part of the process of the M&A. Fourth, the use of various types of outside expert or business consultants is needed. Fifth, the strategic intervention by Human Resource managers is required. Last, sharing M&A information among employees is important as information dissemination will help employees be more receptive to such a change. However, this study has several limitations as a single case study; more varied SME M&A case studies are needed in order to generalize the results of the study. Conclusions - Most of the research dealing with M&As has focused on major companies and PMI and neglected SMEs. Thus, our study focuses on SMEs and the decision-making procedures for M&A. This study has significantly contributed to the literature in this area and has provided practical information around the implications of sound decision-making during M&As. Specifically, the results of the study contribute to the need for research on M&A among SMEs, which to date has often been neglected as a topic of choice.

Bacterial Flora of East China Sea and Yosu Coastal Sea Areas 1. Horizontal Distributions According to Number of Bacteria, Vibrio spp. and Coliform Group (여수연안 및 동중국해의 세균상 1. 일반 세균, Vibrio spp., 대장균군 균수에 따른 수평 분포)

  • JUNG Kyoo-Jin;SHIN Suk-U
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.29 no.1
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    • pp.9-16
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    • 1996
  • In order to understand microbial ecosystem in the fast china sea and Yosu coastal sea horizontal distributions of bacterial flora, Vibrio spp., coliform group, temperature, and salinity in this sea area, were studied 42 sampling stations during 6th-l4th August, 1992. From the results, salinity and temperature were $24.64\~33.78\%_{\circ}$ and $22.53\~29.18^{\circ}C$, respectively. As the open sea far from land goes on, salinity became low while temperature became high. Viable cell counts of bacteral flova, Vibrio spp., and roliform group in Yosu coastal sea water were $1.0\times10^2\~3.0\times10^4/ml,\;0.2\times10\~9.0\times10^3/ml,\;and\;0.3\times10\~3.0\times10^3/ml$ while those of these in the open sea water were $0.4\times10\~2.0\times10^3/ml,\;0.8\times10\~3.0\times10/ml,\;and\;0.9\times10\~1.3\times10/ml$, respectively.

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The Effect of Melatonin on Mouse Jejunal Crypt Cell Survival and Apoptosis (멜라토닌이 생쥐 소낭 세포 재생과 아포토시스에 미치는 영향에 대한 연구)

  • Kang, Jin-Oh;Ha, Eun-Young;Baik, Hyung-Hwan;Cho, Yong-Ho;Hong, Seong-Eon
    • Radiation Oncology Journal
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    • v.18 no.1
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    • pp.60-67
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    • 2000
  • Purpose :To evaluate protective mechanism of melatonin against radiation damage and its relationship with apoptosis in mouse jejunum. Materials and Methods: 168 mice were divided into 28 groups according to radiation dose and matatonin treatment. To analysis crypt survival, microcolony survival assay was done according to Withers and Elkind's method. To analysis apoptosis, TUNEL assay was done according to Labet-Moleur's method. Results : Radiation protection effect of melatonin was demonstrated by crypt survival assay and its effect was stronger in high radiation dose area. Apoptosis index with 8 Gy irradiation was 18.4$\%$ in control group and 16.5$\%$ in melatonin treated group. After 18 Gy, apoptosis index was 17.2$\%$ in control group and 15.4$\%$ in melatonin treated group. Apoptosis index did not show statistically significant difference between melatonin treated group and control group. Conclusion : Melatonin shows clear protective effect in mouse jejunum against radiation damage but its protective effect seems not to be related with apoptosis protection effect.

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EFFECT OF SOIL mOISTURE CONDITiON ON THE GROWTH AND EVAPOTRANSPIRATION OF THE TOBACCO PLANT (토양수분의 과, 부족이 연초의 생장과 증발산량에 미치는 영향)

  • 홍순달;이윤환;김재정;조성진
    • Journal of the Korean Society of Tobacco Science
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    • v.7 no.1
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    • pp.15-23
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    • 1985
  • Growth response and evapotranspiration of tobacco as to each soil moisture condition treated with different height of ground water table such as 30cm, 100cm, 170cm, and 230cm were investigated. The results obtained were as follows; 1. Soil water potential in the rhizosphere (25cm depth from surface) treated with ground water table (G.W.T) of 230 cm was less than -6.5 bar at 60 days after transplanting. 2. Dry weight of leaves per plant was the highest in the pot treated with 100 cm G.W.T and was the lowest in the pot treated with 230 cm G.W.T.. Leaves/Stem ratio of dry weight was the lowest in the pot treated with 230 cm G.W.T. This would show that extension of leaves as compared with elongation of stem was suppressed. .3. In the roster stress condition of 230 cm G.W.T., extension of leaves was continued until the latter growth stage, Relative growth rate of leaf area per plant of the pot with 30 cm G.W.T. was the highest through all growth period after fixation of G.W.7., but owing to lower density of leaf, the dry weight of leaves per plant was less rather than that of the pot with 170 cm G.W.T. at 64 days after transplanting. 4. The highest evapotranspiration per plant per day was shown at the 45th day after transplanting in the pots with 30cm and 100cm G.W.T. and at 60 days in the pots with 170cm and 230cm G.W.T respectively. 5. In the soil moisture conditions with 30cm and 100cm G.W.T., evapotranspiration per plant per hour was much higher in the daytime that at night as well as in clear day than in rain-cloudy day owing to loner relative humidity , but in the water stress condition with 230 cm G.W.T., that was much lower. 6. Total evapotranspiration per plant during the whole growing period of 64 days was in order of 30cm > 100 cm > 170 cm > 230 cm G.W.T.. Total evapotranspiration for 34 days after fixation of G.W.T was much higher at night than in the daytime in case of water stress conditions i.e 170cm and 230cm G.W.T. but in normal condition of the pots with 30cm and 100cm G.W.T. that was much higher in the daytime than at night. 7. Leaf water potential of the 3rd and 6th leaf from top at 64 days after transplanting was in order of 100cm > 30 cm > 170cm > 230cm G.W.T. The reason why leaf water potential in the pot with 30cm was less than that in the pot with 100cm G.W.T. would be the abnormal turgidity with low density of cell substrates by the excess water absorption in the pot with 30cm G.W.T..

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2,4-Dinitrochlorobenzene-induced Atopic Dermatitis Like Immune Alteration in Mice (마우스에서 2,4-Dinitrochlorobenzene을 이용한 아토피성 피부염 발현 관련 면역지표치 분석)

  • Lee, Seung-Hye;Baek, Seong-Jin;Kim, Hyoung-Ah;Heo, Yong
    • Toxicological Research
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    • v.22 no.4
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    • pp.357-364
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    • 2006
  • This study was undertaken to develop a reliable mice model demonstrating similar immunologic phenomena as human atopic dermatitis characterized with predominance of type-2 immune response. BALB/C mice and NC/Nga mice were sensitized twice with $100{\mu}l$ of 1% 2,4-dinitrochlorobenzene (DNCB) or vehicle (acetone : olive oil=4:1 mixture) in a week and challenged twice with $100{\mu}l$ of 0.2% DNCB or the vehicle at the following week. Mice were sacrificed at 19 days following the second DNCB or vehicle challenge for NC/Nga mice and at 28 days following the second DNCB or vehicle challenge for BALB/c mice. Upregulation of plasma 1gE, a hallmark of atopic dermatitis occurrence, was evident in the plasma obtained 4 day after the second DNCB challenge from BALB/c mice (approximately 4-fold) and NC/Nga mice (approximately 6-fold) treated with DNCB in comparison with that of the vehicle treated-control mice, and remain higher $3{\sim}4$ week after the second challenge. Ratio of plasma IgG1 versus IgG2a concentration was significantly higher in the mice treated with DNCB than the control mice, which also implies the skewed type-2 reactivity in vivo. Ratio of interleukin-4 versus interferon gamma produced in the splenic T cell culture supernatants was approximately 3-fold higher in the both strains of mice treated with DNCB than their control mice, respectively. The DNCB-treated mice demonstrated atopic dermatitis-like skin legions characterized with erythma, scaling, and hemorrhage, which was not observed with the control mice. Scratching on face or dorsal area was significantly more frequent (approximately 25-fold) in the DNCB-treated mice than the control at next day of the second DNCB challenge, and scratching frequency remains higher (approximately 4-fold) in the mice treated with DNCB than the control at 14 day following the second DNCB challenge. Overall, the mice model developed through sensitization and challenge with DNCB may be useful for research on atopic dermatitis and development of treatment materials for atopic dermatitis.

Radiation detector material development with multi-layer by hetero-junction for the reduction of leakage current (헤테르접합을 이용한 누설전류 저감을 위한 다층구조의 방사선 검출 물질 개발)

  • Oh, Kyung-Min;Yoon, Min-Seok;Kim, Min-Woo;Cho, Sung-Ho;Nam, Sang-Hee;Park, Ji-Goon
    • Journal of the Korean Society of Radiology
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    • v.3 no.1
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    • pp.11-15
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    • 2009
  • In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using a multi-layer technique to decrease dark current. High efficiency materials in substitution for Amorphous Selenium(a-Se) have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using PN junction or Hetero junction already used as solar cell, semiconductor. Particle-In -Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in Particle-In -Binder method. To make up for the weak points, multi-layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity, signal linearity is measured to evaluate multi-layer radiation sensor material.

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Ideal Freezing Curve Can Avoid the Damage by Latent Heat of Fusion During Freezing (냉동 시 잠재용융열에 의한 피해를 최소화할 수 있는 이상냉동 곡선)

  • 박한기;박영환;윤웅섭;김택수;윤치순;김시호;임상현;김종훈;곽영태
    • Journal of Chest Surgery
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    • v.36 no.4
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    • pp.219-228
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    • 2003
  • Background:Liquid nitrogen freezing techniques have already met with widespread success in biology and medicine as a means of long-term storage for cells and tissues. The use of cryoprotectants such as glycerol and dimethylsulphoxide to prevent ice crystal formation, with carefully controlled rates of freezing and thawing, allows both structure and viability to be retained almost indefinitely. Cryopreservation of various tissues has various con-trolled rates of freezing. Material and Method: To find the optimal freezing curve and the chamber temperature, we approached the thermodynamic calculation of tissues in two ways. One is the direct calculation method. We should know the thermophysical characteristics of all components, latent heat of fusion, area, density and volume, etc. This kind of calculation is so sophisticated and some variables may not be determined. The other is the indirect calculation method. We performed the tissue freezing with already used freezing curve and we observed the actual freezing curve of that tissue. And we modified the freezing curve with several steps of calculation, polynomial regression analysis, time constant calculation, thermal response calculation and inverse calculation of chamber temperature. Result: We applied that freezing program on mesenchymal stem cell, chondrocyte, and osteoblast. The tissue temperature decreased according to the ideal freezing curve without temperature rising. We did not find any differences in survival. The reason is postulated to be that freezing material is too small and contains cellular components. We expect the significant difference in cellular viability if the freezing curve is applied on a large scale of tissues. Conclusion: This program would be helpful in finding the chamber temperature for the ideal freezing curie easily.

Influence of Nanostructured TiO2 Electrode Fabricated with Acid-treated Paste on the Photovoltaic Efficiency of Dye-Sensitized Solar Cells (산처리된 페이스트로 제조한 나노 구조체 TiO2 전극이 염료감응형 태양전지의 효율에 미치는 영향)

  • Lee, Jae-Wook;Hwang, Kyung-Jun;Roh, Sung-Hee;Kim, Sun-Il
    • Applied Chemistry for Engineering
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    • v.18 no.4
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    • pp.356-360
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    • 2007
  • Recently, dye sensitized solar cells (DSSCs) composed of nanoporous $TiO_2$, light-sensitive dyes, electrolytes, and counter electrode have been received much attention. Nanostructured particles with higher surface area for the higher adsorption of Ru (II) dye are required to increase the quantity of light absorption. Also, it has been reported that the key factor to achieve high energy conversion efficiency in the photoelectrode of DSSC is the heat treatment of $TiO_2$ paste with acid addition. In this work, we investigated the influence of acid treatment of $TiO_2$ solar cell on the photovoltaic performance of DSSC. The working electrodes fabricated in this work were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), field emission scanning electron microscope (FE-SEM), and atomic force microscope (AFM). In addition, the influence of nanostructured photoelectrode fabricated with the acid-treated paste on the energy conversion efficiency was investigated on the basis of photocurrent-potential curves. It was found that the influence of acid-treated paste on the photovoltaic efficiency was significant.

Studies on the proliferative activity and the expression of c-myc and ras of preneoplastic hepatocytes in rats (랫드 전암 간세포의 증식성과 c-myc, ras의 발현에 관한 연구)

  • Cho, Ho-seong;Park, Nam-yong
    • Korean Journal of Veterinary Research
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    • v.40 no.1
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    • pp.117-129
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    • 2000
  • This study was carried out to examine proliferative activity and expression of c-myc oncoprotein and p2lras in normal and preneoplastic rat livers induced by an in vivo mid-term chemical carcinogenesis assay. Sixty, six-week-old male specific pathogen free Sprague-Dawley male rats were randomly divided into five groups. Group I was received a single intraperitoneal(IP) dose(200mg/kg) of diethylnitrosamine(DEN). Group 2(10 rats) was operated partial hepatectomy(PH) and Group 3 was received IP(200mg/kg) DEN, fed two weeks later with 500ppm of phenobarbital(PB). Group 4 was received IP(200mg/kg) DEN, fed two weeks later 500ppm(PB) and PH at week 3 after the onset of experiment. While group 5(20 rats) was not treated and used as a control group. All the rats were sacrificed at age 14 weeks except 10 rats from group 5 were sacrificed at the onset of experiment. Livers of all rats were examined for 5-bromo-2'-deoxyuridine(BrdU) incoporation, proliferating cell nuclear antigen(PCNA), silver-binding nucleolar organizer regions(AgNORs) counts per nucleus and expression of c-myc oncoprotein and p21ras. Both the number and area of the preneoplastic lesions were significantly(p<0.01) compared to other groups. A significant(p<0.01) increase in immunoreactive cells were detected in preneoplastic hepatocytes in Groups 3 and 4 by PCNA and BrdU immunohistochemical stain. The number of the positive cells were significantly(p<0.05) lower in normal 14-week-old rats than those of 6-week-old rats. The results showed that proliferative activity of the hepatocytes was increased by treatment with DEN, PH and PB. Meanwhile, AgNORs counts per nucleus were significantly(p<0.05) increased in the preneoplastic hepatocytes of rats in both groups 3 and 4. The expression of c-myc oncoprotein and p21ras were more readily localized within the hepatic preneoplastic lesions such as hyperplastic nodules. Especially, group 4 showed significantly (p<0.05) overexpressed levels compared to groups 1 and 3. These findings suggest that PCNA, BrdU and AgNORs are significantly increased and c-myc oncoprotein and p21ras are significantly overexpressed in hepatic preneoplastic lesions induced by mid-term carcinogenesis. So these parameters can be an effective markers for hepatic prencoplastic lesions.

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