• Molecules and Cells
• /
• v.40 no.2
• /
• pp.117-122
• /
• 2017

Despite the fact that porcine embryonic stem cells (ESCs) are a practical study tool, in vitro long-term maintenance of these cells is difficult in a two-dimensional (2D) microenvironment using cellular niche or extracellular matrix proteins. However, a three-dimensional (3D) microenvironment, similar to that enclosing the inner cell mass of the blastocyst, may improve in vitro maintenance of self-renewal. Accordingly, as a first step toward constructing a 3D microenvironment optimized to maintain porcine ESC self-renewal, we investigated different culture dimensions for porcine ICM-derived cells to enhance the maintenance of self-renewal. Porcine ICM-derived cells were cultured in agarose-based 3D hydrogel with self-renewal-friendly mechanics and in 2D culture plates with or without feeder cells. Subsequently, the effects of the 3D microenvironment on maintenance of self-renewal were identified by analyzing colony formation and morphology, alkaline phosphatase (AP) activity, and transcriptional and translational regulation of self-renewal-related genes. The 3D microenvironment using a 1.5% (w/v) agarose-based 3D hydrogel resulted in significantly more colonies with stereoscopic morphology, significantly improved AP activity, and increased protein expression of self-renewal-related genes compared to those in the 2D microenvironment. These results demonstrate that self-renewal of porcine ICM-derived cells can be maintained more effectively in a 3D microenvironment than in a 2D microenvironment. These results will help develop novel culture systems for ICM-derived cells derived from diverse species, which will contribute to stimulating basic and applicable studies related to ESCs.

• Molecules and Cells
• /
• v.43 no.9
• /
• pp.763-773
• /
• 2020

Recently, tumor microenvironment (TME) and its stromal constituents have provided profound insights into understanding alterations in tumor behavior. After each identification regarding the unique roles of TME compartments, non-malignant stromal cells are found to provide a sufficient tumorigenic niche for cancer cells. Of these TME constituents, adipocytes represent a dynamic population mediating endocrine effects to facilitate the crosstalk between cancer cells and distant organs, as well as the interplay with nearby tumor cells. To date, the prevalence of obesity has emphasized the significance of metabolic homeostasis along with adipose tissue (AT) inflammation, cancer incidence, and multiple pathological disorders. In this review, we summarized distinct characteristics of hypertrophic adipocytes and cancer to highlight the importance of an individual's metabolic health during cancer therapy. As AT undergoes inflammatory alterations inducing tissue remodeling, immune cell infiltration, and vascularization, these features directly influence the TME by favoring tumor progression. A comparison between inflammatory AT and progressing cancer could potentially provide crucial insights into delineating the complex communication network between uncontrolled hyperplastic tumors and their microenvironmental components. In turn, the comparison will unravel the underlying properties of dynamic tumor behavior, advocating possible therapeutic targets within TME constituents.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.301-301
• /
• 2010

2010년경 2.5G APD 시장은 3, 000억원 규모로 증가하는데 이는 FTTH 망의 확산에 힘입은 바 크다. 이와 같이 중요한 APD 소자는 현재 광통신 부품시장을 석권해 가고 있는 대만, 중국 업체들은 제조기술을 갖고 있지 않고 주로 미국-일본 기술에 의존하고 있기 때문에 Niche market으로 중요한 부품이라 할 수 있다. APD의 증폭은 높은 전기장에 의해 얻어지는데, 이 때문에 메사형 구조로는 신뢰성을 확보하기 어렵게 되고 따라서 평면형(Planar) 구조로 설계-제작하게 된다. APD 소자는 증폭층의 너비에 의해 APD의 이득-대역폭이 정해지므로 증폭층 폭을 정확하게 조절하는 것은 매우 중요하다. 증폭층의 폭은 에피 성장과 같은 높은 정밀성을 갖는 장비에 의해 조절하는 것이 아니라, Planar 구조의 특성상 Zn-확산에 의해 조절하게 된다. 대부분의 경우 Zn-확산은 Zn 또는 $Zn_3P_2$를 증착하여 drive-in 시키는 방법을 사용하는데, 이 경우 Zn가 interstitial site를 치고 들어감으로 인해 캐리어 농도가 $2{\times}10^{17}\;cm^{-3}$ 정도로 낮게 형성된다. 따라서 높은 인가 바이어스에서 p-side로 공핍층이 전개되기 때문에 증폭층의 폭을 조절하기가 매우 어렵다. 이 현상은 APD 제작에 있어서 수율과 관련이 깊다. 따라서 APD의 증폭층 폭을 tight하게 조절하기 위해서는 p-type 캐리어 농도를 높일 수 있는 gas-phase 확산 방식의 개발이 필요하다. 이 방식에는 Ampoule과 같은 closed tube 방식과 확산로와 같이 Gas를 지속적으로 흘려주면서 확산시키는 open-tube 방식이 있다. Ampoule 방식은 캐리어 농도 측면에서는 가장 좋은 방식이나, Ampoule의 size 및 온도 균일성 등으로 인해 생산성에 문제가 있다. 따라서 open-tube 방식의 확산기술개발은 매우 중요하다 할 수 있다. 본 연구에는 rapid thermal annealing (RTA) 방법에 의한 $Zn_3P_2$ 고체의 확산 방식과 DEZn MO source에 의한 Gas 확산 방식을 바탕으로 InP로의 확산된 Zn원자와 doping의 분포를 비교하였다. 실험결과, Gas 확산방식의 경우 Zn원자가 더욱 더 깊게 확산이 되었으며, 확산된 원자의 대부분이 도펀트로 작용함을 확인할 수 있었다.

• Hwankyungkyoyuk
• /
• v.15 no.1
• /
• pp.137-147
• /
• 2002

The progress of environmental science and technology in the developed countries has been rapid in recent years. Particularly remarkable has been the advancement of various pollutant control measures, which have brought the pollution of inorganic factors such as air and water under control. In contrast, diversity of the ecosphere, of which man is a part, is being steadily Impoverished and the biological community is getting unvaryingly uniform. These phenomena were brought about by the expansion of artificial environment such as new industrial complexes, transportation facilities and urban development. Man has constructed uniform and artificial environment, believing in the premise of confrontation with nature, to such a scale that the natural environment and biological community have lost their balance. This will increasingly endanger the soundness of the biotic environment of nature, which constitutes the potential foundation both for the survival environment of man as biological entity and for the development of human civilization. In order to guarantee the soundness of man's body, intelligence and sensitivity as wholesome gene Pool on the earth and for the future of man, primarily important environmental education is the understanding of how man can everlasting exist in and with the survival environment. In view of this reality, it is vitally important to create ecologically diverse and well-balanced environment with living materials, i.e., vegetation in order to secure lasting survival environment for man. This task is urgently required in highly artificial environment where non-biological materials have forced the impoverishment of the biological community. Therefore, environmental education for the future should not be totally oriented to technology as that in the past nor it is limited to the medical aspect where well-being of human is the sole object of concern. That is to say, environmental education for the future should be one that provides knowledge that human can understand his place based on the ecological concept and thereby make him to have ethical consciousness that he can control his behavior within the reasonable level for ecological niche who he is located.

• Hwankyungkyoyuk
• /
• v.13 no.1
• /
• pp.65-74
• /
• 2000

Environmentally literated students and adults should be able to use and apply the basic ecological concepts when considering environmental problems and issues. Because ecology forms the foundation of environmental education, a review of the literatures on the degree of students' understanding for ecological concepts can provide useful insights for environmental educators. The purposes of this study were as follows: first, to analyse the parts connected with ecological knowledge of two environmental education books, ‘environments’(middle school) and ‘environmental science’(high school), second, to investigate the level of understanding on ecological concepts by the use of new developed instrument. The 20 most important ecological concepts from Cherrett(1989) and the important ecological concepts' lists from Hungerford and Volk(1990), Ramsey, Hungerford and Volk(1992), Volk(1993) would be recognized and endorsed by most environmental educators as concepts essential to environmental literacy, We referenced these informations and sequenced ecological knowledge as four main categories(communities, populations, ecosystem, man as a component of the nature systems). We have used it as a criterion in the analysis of teaching materials and the development of a new test instrument($\alpha$=0.81). According to the analysed results, the understanding levels for scales and relationships of communities, populations, ecosystem were high but those for individual concepts and differences were low. By the analysis of Korean High School EE book, ‘environmental science’, learning for some concepts(succession, material cycling, niche etc.) has pointed out as one of problems. Environmental educators must pay a careful attention to the concepts that showed high rates of incorrect answer and this work will contribute toward consolidating the basis of EE and help the accomplishment of the ultimate goals in EE.

• The Journal of the Korea Contents Association
• /
• v.19 no.6
• /
• pp.334-346
• /
• 2019

This study aims to investigate the appearance of Gyeongridangil and its related commercial streets, which seemingly serve as a place brand. Internet trend data, locational conditions, and commercial compositions were analyzed to determine the characteristics of their formation. Result showed that, as the commercial streets developed because of social network services, the street names tended to be considered as place images. In terms of locational conditions, they chose rather remote places, risking the disadvantages for their own spatial style. Interpreted within the framework of place branding, these streets seemed to identify themselves with a unique streetscape using spatial restraints as an advantage. They positioned in a niche area to avoid conflict with other commercial types and attract consumers with the image of "suppliers of trendy lifestyle", thus successfully becoming a place brand.

• Journal of the Economic Geographical Society of Korea
• /
• v.22 no.1
• /
• pp.36-51
• /
• 2019

The purpose of this study is to elucidate the implications for the effective use of rental housing REITs in Korea by analyzing the characteristics of rental housing REITs in Japan, focusing on the operation and asset management of rental housing REITs. The main results of the study are as follows. In the case of Japan, rental housing REITs are invested and operated by profit-based private companies, and are activated with small rental housing in the city center as a niche market. In particular, it has secured the reliability, expertise and permanence of REITs by utilizing the sponsored REITs structure. This is possible because Japan has infrastructure for the supply and operation of corporate rental housing. Based on these analyses, ways to revitalize private investment, and ways to utilize sponsored REITs to enhance REITs' credibility were derived. for the effective use of domestic rental housing REITs.

• Korea and Global Affairs
• /
• v.3 no.1
• /
• pp.151-182
• /
• 2019

Rise of China has correspondingly seen increased Chinese involvement at global stage and regional levels in different parts of the world. This has attracted claims of strategic competition and rivalry between China and U.S., as China is said to be working towards replacing hitherto U.S. influence. Consequently there have been calls for U.S. to counter increased Chinese involvement to safeguard U.S. influences and interests. This study aims to contribute to this debate by examining the extent to which increased Chinese involvement in Africa has, if any, supplanted U.S. strategic interests in the continent. The study contends that, Chinese involvement in Africa has entailed China creating own niche that does not necessary threaten U.S. interests in the continent as widely portrayed and imagined. This is premised on the fact that, U.S. has historically had relatively minimal strategic interests in Africa as compared to other more strategic parts of the world that China could significantly threaten. Seen in this way, increased Chinese penetration in Africa has not had immediate threats to U.S. core strategic interests, thus explaining U.S. measured response to counter Chinese presence in Africa.

• Journal of Ecology and Environment
• /
• v.45 no.3
• /
• pp.130-142
• /
• 2021

Background: Climate change is occurring rapidly around the world, and is predicted to have a large impact on biodiversity. Various studies have shown that climate change can alter the geographical distribution of wild bees. As climate change affects the species distribution and causes range shift, the degree of range shift and the quality of the habitats are becoming more important for securing the species diversity. In addition, those pollinator insects are contributing not only to shaping the natural ecosystem but also to increased crop production. The distributional and habitat quality changes of wild bees are of utmost importance in the climate change era. This study aims to investigate the impact of climate change on distributional and habitat quality changes of five wild bees in northwestern regions of Iran under two representative concentration pathway scenarios (RCP 4.5 and RCP 8.5). We used species distribution models to predict the potential range shift of these species in the year 2070. Result: The effects of climate change on different species are different, and the increase in temperature mainly expands the distribution ranges of wild bees, except for one species that is estimated to have a reduced potential range. Therefore, the increase in temperature would force wild bees to shift to higher latitudes. There was also significant uncertainty in the use of different models and the number of environmental layers employed in the modeling of habitat suitability. Conclusion: The increase in temperature caused the expansion of species distribution and wider areas would be available to the studied species in the future. However, not all of this possible range may include high-quality habitats, and wild bees may limit their niche to suitable habitats. On the other hand, the movement of species to higher latitudes will cause a mismatch between farms and suitable areas for wild bees, and as a result, farmers will face a shortage of pollination from wild bees. We suggest that farmers in these areas be aware of the effects of climate change on agricultural production and consider the use of managed bees in the future.

• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.35-48
• /
• 2021

With the advent of the Fourth Industrial Revolution, startups are leading the proliferation of logistics in life services in countries across the world. Logistics in life startups aim to differentiate themselves for traditional logistics companies by offering customized services that penetrate niche logistics market and enhance customer convenience and satisfaction. Through the development of mobile applications(apps) and platform a variety of life-enhancing services are becoming increasingly available to customers, such as on-demand, online-to-offline, convenience, reverse logistics, as well as last-mile delivery. In particular, logistics in life services are expanding into areas that include food delivery, home moving, cargo transport, laundry delivery, car washing, and car repair. In order for the logistics in life startups to succeed, they needs to offer highly usable apps to increase customer satisfaction and loyalty. Due to the nature of mobile phones, different evaluation criteria than those for websits should be used to determine the usability of apps. The purpose of this study is to evaluate the usability of representative Korean logistics in life apps through usability testing, discuss implications and offer improvement recommendations. Finally, the best Korean logistics app is compared with a top ranked app on Google Play for benchmarking purposes.