• Toxicological Research
• /
• 제26권1호
• /
• pp.15-19
• /
• 2010

Mesenchymal stem cells (MSCs) have greater potential for immediate clinical and toxicological applications, due to their ability to self-renew, proliferate, and differentiate into a variety of cell types. To identify novel candidate genes that were specifically expressed during transdifferentiation of human MSCs to neuronal cells, we performed a differential expression analysis with random priming approach using annealing control primer-based differential display reverse transcription-polymerase chain reaction approach. We identified genes for acyl-CoA thioesterase, tissue inhibitor of metalloproteinases-1, brain glycogen phosphorylase, ubiquitin C-terminal hydrolase and aldehyde reductase were up-regualted, whereas genes for transgelin and heparan sulfate proteoglycan were down-regulated in MSC-derived neurons. These differentially expressed genes may have potential role in regulation of neurogenesis. This study could be applied to environmental toxicology in the field of testing the toxicity of a chemical or a physical agent.

• Molecules and Cells
• /
• 제38권3호
• /
• pp.202-209
• /
• 2015

Hepatocellular carcinoma (HCC), a highly malignant disease and the third leading cause of all cancer mortalities worldwide, often responses poorly to current treatments and results in dismal outcomes due to frequent chemoresistance and tumor relapse. The heterogeneity of HCC is an important attribute of the disease. It is the outcome of many factors, including the cross-talk between tumor cells within the tumor microenvironment and the acquisition and accumulation of genetic and epigenetic alterations in tumor cells. In addition, there is accumulating evidence in recent years to show that the malignancy of HCC can be attributed partly to the presence of cancer stem cell (CSC). CSCs are capable to self-renew, differentiate and initiate tumor formation. The regulation of the stem cell-like properties by several important signaling pathways have been found to endow the tumor cells with an increased level of tumorigenicity, chemoresistance, and metastatic ability. In this review, we will discuss the recent findings on hepatic CSCs, with special emphasis on their putative origins, relationship with hepatitis viruses, regulatory signaling networks, tumor microenvironment, and how these factors control the stemness of hepatic CSCs. We will also discuss some novel therapeutic strategies targeted at hepatic CSCs for combating HCC and perspectives of future investigation.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.3-8
• /
• 2001

The mineral industry of the United States is going through a challenging time. The US as an industrial nation faces with increasing demand in raw materials to fuel various industrial sectors but, at the same time, meeting environmental constraints associated with excavating and extracting these raw materials. In addition, gradual depletion of material resources. and the necessity of handling more complex forms of resources of primary origin have led to a decline in her resource productivity, once a strategic advantage of the U.S. As a result. the United States currently relies heavily upon foreign importation of various materials such as precious and strategic metals. However, since the US is the major consumer of most of these materials, the recovery of these values from scrap would help renew her position as a resource-producing nation, and ultimately help spur its domestic economy. Furthermore. recycling would also help maintain a clean environment and reduce energy consumption. In this paper. the author attempts to discuss opportunities and challenges lied ahead of the US mineral in relation to recovering their much-needed resources from secondary sources. The need and demand in various metals in the US will be reviewed and discussed. The implication of resource recovery from secondary sources will also be discussed. Extraction methods treating secondary sources are inherently different from those for primary sources. There is a need for new technologies which are metallurgically efficient and environmentally benign in treating secondary sources. Ways to meet such a need will be examined and key factors to be considered in approaching these challenges will be discussed.

• 한국정보통신학회논문지
• /
• 제10권3호
• /
• pp.571-578
• /
• 2006

모바일 이동 통신에서 단말기의 분실 또는 단말기의 비밀 정보 유출에 의한 도청이나 통신도용과 같은 경우를 예방하기 위해서 특정 단말기를 배재하고 신속하게 그룹 비밀키를 갱신할 수 있어야 한다. 본 논문에서 제안된 그룹키 갱신 메카니즘은 Fiat-Shamir 방식을 적용하여 회의장 등과 같이 특정한 공간에서 소규모 그룹회의를 고려한 쉬운 키 생성과 갱신을 위주로 오직 사전에 허가된 사용자만이 그룹키를 이용하여 디지털 정보를 얻을 수 있게 한다. 이는 키 갱신을 위해 필요한 비밀 정보가 단말기에 의해서 생성이 되고 상호 통신을 위한 새로운 그룹키가 갱신 되므로 단말기 의 안전성을 보장할 수 있다.

• 한국기계가공학회지
• /
• 제11권2호
• /
• pp.144-151
• /
• 2012

Polishing is not only one of the most frequently adopted processes in modern industries, but also the most critical one to the surface quality of the products such as semi conductor wafers and LED sapphire wafers. With the required specifications for the wafer surface quality getting more and more strengthened, the manufacturers are spending huge amount of cost to renew the machine to meet the enhanced surface specifications. Surface qualities of the wafers are mostly damaged by the structural vibrations of the polishing machines. In this paper, the dynamic characteristics of a wafer polishing machine have been analyzed through the frequency response test and the computer simulation. And the supporting structure of a polishing machine has been investigated to minimize the vibration transmissions, to improve the stability of the machine and further to reduce the defects of the polished products. The result of the study shows that simple design modifications of the supporting structure without altering the main structure of the machine can substantially suppress the vibrations of the machine with negligible expenses.

• 한국작물학회지
• /
• 제51권6호
• /
• pp.497-504
• /
• 2006

Biodiversity is closely related to the conservation of ecosystems. Ecosystems provide more subtle, but equally essential, services. Microorganisms decompose human's waste and renew the soils that produce our food crops. Biodiversity in Korean paddies encompass 54 families and 107 species of freshwater invertebrates. In terms of the number of aquatic insects affected by different sources, the order starting with the highest population was swine slurry > chemical fertilizer > fresh straw with reduced fertilizers > control. The number of freshwater invertebrate and aquatic macro-invertebrate in surface water of the plots without insecticidal application were 2 and 2.1 times greater than in fields receiving insecticide applications, respectively. The soil microfungal flora of the 85 isolates paddy fields in Korea was 30 species in 13 genera and 11 isolates were unidentified yet. Agricultural policy should be changed to assist the conservation of biodiversity because until now the agricultural ecosystems have been negatively affected from the development of high-yield varieties to enhance food production, and the expansion of fertilizer and chemical use. For the conservation of agricultural ecosystems, agricultural practices with less investment and more resource saving, as well as enhancing the safety of agricultural and livestock products are essential. Finally, this paper was written for the contribution for the development of environmentally friendly farming systems with neighboring or whole ecosystems.

• 대한수학교육학회지:학교수학
• /
• 제6권2호
• /
• pp.181-211
• /
• 2004

본 연구는 최근 2000년대를 향한 세계 여러 나라의 수학 교육과정 개정의 결과들을 살펴봄으로써 우리나라 제 7차 수학 교육과정 개정 노력에 대한 반성적 고찰을 위한 기초 자료를 마련하는 데 그 목적이 있다. 이러한 목적을 달성하기 위하여 수학교육의 오랜 전통을 지녔으나 국내에 잘 알려지지 않은 독일의 수학 교육과정의 구성체제와 구성내용을 Nordrhein-Westfalen 주를 중심으로 구체적으로 살펴보고, 우리나라 수학교육과정과 그 특징을 비교하였다 마지막으로 앞에서 살펴본 내용을 바탕으로 우리나라 수학교육과정의 발전적 고찰을 위한 시사점을 논하였다.

• 공학교육연구
• /
• 제14권3호
• /
• pp.45-54
• /
• 2011

The purpose of this study is to analyze performance problems in establishing and improving program educational objectives (PEO) and to set up action strategies for the civil engineering program at the A university. To fulfill the purpose, according to the typical needs analysis model, research problems were defined, current conditions and desired conditions were identified, discrepancies and their reasons were examined, and action strategies were derived. Current conditions and desired conditions were identified by analyzing the A civil engineering program's self study report, conducting surveys and interviews with constituents. After the discrepancies and the reasons were examined, performance problems and field force analysis were conducted to draw short term and long term action strategies to improve PEO. Short term action strategies were to announce PEO to current students, to hold faculty seminars to establish and to improve PEO, to renew the list of constituents regularly, to composite an annual milestone, to define roles of the committees, and to enforce educational opportunity toward industrial advisory board members. For the long term strategies, improvement and documentation of PEO assessment system, collection and analysis of constituents' suggestions, establishment of effective accreditation support system, and arrangement of compensation system for the faculties who are in charge of engineering education accreditation responsibility.

• Journal of Communications and Networks
• /
• 제13권6호
• /
• pp.583-590
• /
• 2011

Full-mesh IPSec tunnels pass through a black ("unsecure") network (B-NET) to any red ("secure") networks (RNETs). These are needed in military environments, because they enable dynamically changing R-NETs to be reached from a BNET. A dynamically reconfiguring security policy database (SPD) is very difficult to manage, since the R-NETs are mobile. This paper proposes advertisement process technologies in association with the tunnel gateway's protocol that sends 'hello' and 'prefix advertisement (ADV)' packets periodically to a multicast IP address to solve mobility and security issues. We focus on the tunnel gateway's security policy (SP) adaptation protocol that enables R-NETs to adapt to mobile environments and allows them to renew services rapidly soon after their redeployment. The prefix ADV process enables tunnel gateways to gather information associated with the dynamic changes of prefixes and the tunnel gateway's status (that is, 'down'/restart). Finally, we observe two different types of performance results. First, we explore the effects of different levels of R-NET movements on SP adaptation latency. Next, we derive the other SP adaptation latency. This can suffer from dynamic deployments of tunnel gateways, during which the protocol data traffic associated with the prefix ADV protocol data unit is expected to be severe, especially when a certain tunnel gateway restarts.

• 대한수의학회지
• /
• 제53권2호
• /
• pp.109-115
• /
• 2013

Cancers are mainly sustained by a small pool of neoplastic cells, known as cancer stem cells or tumorinitiating cells. These cells possess the ability to self-renew and proliferate, and are thus able to form the tumor. In the present study cells that correspond to cancer stem cells in mammary and liver cancers in animals were identified by the expression of CD133, CD44, CK7, and OCT4 using immunochemistry. As a result, we found with CD133+ and CD44+ cancer stem cell-like phenotypes in mouse and canine hepatocellular carcinoma and canine mammary gland tumors. However, CK7+ and OCT4+ cells were not identified in animal mammary and liver cancer. CD133+ and CD44+ cells are wellknown stem cell lines and play key roles in development and metastasis in human cancer. These findings suggest that cancer stem cells are involved in animal tumorigenesis and may provide insight into mechanisms in cancer development as well as cancer diagnostics.