• The Korean Journal of Ecology
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• 제26권1호
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• pp.34-38
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• 2003

본고에서는 1993년 지정 해제된 천연기념물 제4호인 통의동 백송의 나이(당시 630살로 추정)와 직경 생장 유형을 분석하였다. 그 결과 이 나무의 나이는 1993년 당시 약 300살로 추정되는데, 원래 추정한 나이는 매우 과대 추정한 나이라고 할 수 있다. 이 나무는 주변의 토양수분 상태에 따라서 그 생육의 정도가 상당히 크게 영향을 받아왔다. 특히 1910년부터 약 30년동안 저하된 생장이 지속되었기 때문에 이 나무의 수세는 매우 쇠약해졌고, 이러한 지속적인 생장의 저하가 궁극적으로 이 수목이 죽게 되는데 가장 중요한 원인이 되었던 것으로 판단된다. 이러한 지속적인 생장의 저하가 1910년부터 4년간 지속된 서울지방의 가뭄에 의해서 초래된 것인지는 분명하지는 않으나, 이러한 가뭄도 수목 생장의 쇠퇴를 초래한 여러 가지 환경요인중의 하나가 된다는 것은 그리 어렵지 않게 추정할 수 있다. 이 연구를 통해서 우리나라 천연기념물로 지정된 나이가 오래된 나무인 노거수를 잘 관리해야 할 문화 재청이 고려를 해야할 관리상의 문제점에 대한 사항을 고찰하였다.

• Journal of Korean Society for Atmospheric Environment
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• 제10권E호
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• pp.371-386
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• 1994

본 연구소는 최근 대기오염과 산성비 때문에 남산의 소나무가 죽어간다는 일부 학자들의 주장의 진위를 실증적으로 검정하기 위하여 남산에 생육하는 소나무의 생장변화를 정밀분석하고 그것에 대한 생태학적인 해석을 시도함과 아울러, 현재 상태의 대기오염이 소나무의 생육에 미칠 수 있는 영향을 추론하고자 시도되었다. 남산의 3개 지점에서 40그루 나무의 나이테를 조사한 바, 대다수의 남산소나무들은 최근 10년동안에 지금까지 자라온 평균생장량에 비하여 더욱 빠른 생장을 보여주었고 그동안 솔잎혹파리나 아까시나무 등과 같이 생물적인 요인에 의하여 생장의 장해를 받아온 기록을 많이 볼 수 있었다. 더욱이 나무가 생장하는데 가장 중요한 인자의 하나인 토양수분요인이 수목의 생장에 미치는 영향을 조사해 보았을 때 남산위에 분포하는 나무들은 가뭄현상에 대하여 매우 민감하게 그 생육이 조절되는 생장유형을 보여 주었다. 다양한 환경오염 요인들에 대하여 면밀한 검토없이 제기된 일부 학자들의 상기 주장은 설득력을 갖지 못할 뿐만 아니라 매우 성급한 것인 바, 본 연구를 통하여 필자는 남산에 있는 소나무를 대상으로 대기오염의 피해를 논하는 것은 적절하지 못하다는 것을 밝혔다. 특히 현재단계에 있어서 서울 중심지역인 남산에 있어서 대기오염물질과 강우산도와 같은 환경요인은 장기적으로 만성적인 피해를 줄 수도 있는 것으로 추정할 수 있다. 이러한 결과는 수목의 나이테에 대한 집중적 조사와 다양한 환경요인의 변화양상에 관한 연구를 통하여 제시할 수 있었던 바, 추후 남산내 다른 지점의 소나무 뿐 만 아니라 신갈나무와 아카시아나무와 같은 다른 수종의 생장 및 환경오염물질의 부하와 생태계내에서 그들이 변화하는 동태를 포함한 더욱 광범위한 생태계 생태학적 차원에서의 연구가 시행되어야 할 필요가 있다.

• ETRI Journal
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• 제26권6호
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• pp.575-582
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• 2004

Fully-depleted silicon-on-insulator (FD-SOI) devices with a 15 nm SOI layer thickness and 60 nm gate lengths for analog applications have been investigated. The Si selective epitaxial growth (SEG) process was well optimized. Both the single- raised (SR) and double-raised (DR) source/drain (S/D) processes have been studied to reduce parasitic series resistance and improve device performance. For the DR S/D process, the saturation currents of both NMOS and PMOS are improved by 8 and 18%, respectively, compared with the SR S/D process. The self-heating effect is evaluated for both body contact and body floating SOI devices. The body contact transistor shows a reduced self-heating ratio, compared with the body floating transistor. The static noise margin of an SOI device with a $1.1\;{\mu}m^2$ 6T-SRAM cell is 190 mV, and the ring oscillator speed is improved by 25 % compared with bulk devices. The DR S/D process shows a higher open loop voltage gain than the SR S/D process. A 15 nm ultra-thin body (UTB) SOI device with a DR S/D process shows the same level of noise characteristics at both the body contact and body floating transistors. Also, we observed that noise characteristics of a 15 nm UTB SOI device are comparable to those of bulk Si devices.

• 대한조선학회논문집
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• 제47권1호
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• pp.67-75
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• 2010

Submarine and deep sea diving structures are generally designed based on their ultimate strength. Fatigue strength at welded joint must be also taken into account because working stress is increased due to the increasing of diving depth and using high yield steel. The pressure hulls of submarine are subjected to fluctuating compressive loading. But in addition to the calculated stresses, high residual tensile stresses at welded part have to be considered. The state of stress level of pressure hull is tensile at surface and compressive at deep diving depth. This paper presents the results of an experimental investigation on the crack initiation and growth at the weld toe of T welded joints of HY-100 steel plate under constant amplitude loading. It is also investigated the phenomenon of the fatigue failure and test methods. Fatigue tests have been using real scaled local structural models of full penetration T-welded joint, which is a part of the cylindrical shell structures reinforced by ring stiffeners. Several load ratios under constant amplitude loading are considered in the tests. Crack initiation and growth characteristics are examined based on the beach marks of the cracked section of the test specimens. A design stress-life curve including the design formula is suggested according to tested data.

• 한국환경생태학회지
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• 제14권1호
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• pp.46-56
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• 2000

경주 황성공원의 식생구조를 파악하여 생태적 가치를 알아보고, 바람직한 관리방안을 제시하기 위하여 공원 내에 $10m{\times}10m$의 조사구 20개를 설치하고, 군집구조조사를 실시하였다. 군집을 분리하기 위하여 TWINSPAN과 DCA를 이용하였으며, DCA분석결과 소나무군집(A), 소나무군집(B), 참나무류-소나무군집, 아까시나무군집, 그리고 신갈나무군집의 5개로 분리되었다. 종다양도 분석에서 20개 조사구에 걸쳐 목본수종이 총29종 출현하였으나 종조성은 단순하게 나타났다. 각 조사구당 평균출현종수는 $5.32{\pm}2.9$종이었고, 흉고직 경급별 분석에서 소나무는 주로 DBH 27~47cm계급에 분포하였다. 연륜 및 생장분석결과 역사적, 생태적으로 가치가 있는 소나무림이 최근 들어 생장이 둔화되고 있었다. 이상의 조사결과를 바탕으로 관리제언이 제시되었다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권4호
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• pp.1343-1348
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• 2015

Human UHRF1 (ubiquitin-like PHD and RING finger domain-containing 1) has been reported to be over-expressed in many cancers, but its role in ovarian cancer remains elusive. Here, we determined whether knockdown of UHRF1 by lentivirus-mediated shRNA could inhibit ovarian cancer cell growth. Lentivirus-mediated short hairpin RNAs (lv-shRNAs-UHRF1) were designed to trigger the gene silencing RNA interference (RNAi) pathway. The efficiency of lentivirus-mediated shRNA infection into HO-8910 and HO-8910 PM cells was determined using fluorescence microscopy to observe lentivirus-mediated GFP expression and was confirmed to be over 80 percent. UHRF1 expression in infected HO-8910 and HO-8910 PM was evaluated by real-time PCR and Western blot analysis. The Cell Counting Kit-8 (CCK-8) assay was used to measure cell viability; flow cytometry and Hoechst 33342 assay was applied to measure cell cycle arrest and apoptosis. Cell invasion was assessed using transwell chambers. Our results demonstrated that the loss of UHRF1 promoted HO-8910 and HO-8910 PM cell apoptosis, while inhibiting cell proliferation. In addition, UHRF1 knockdown significantly inhibited the invasion of human ovarian cancer cells. In the present study, we also showed that depleting HO-8910 cells of UHRF1 caused activation of the DNA damage response pathway, with the cell cycle arrested in G2/M-phase. The DNA damage response in cells depleted of UHRF1 was illustrated by phosphorylation of CHK (checkpoint kinase) 2 on Thr68, phosphorylation of CDC25 (cell division control 25) on Ser 216 and phosphorylation of CDK1 (cyclin-dependent kinase 1) on Tyr 15.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1331-1335
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• 2004

Angiogenesis is essential for the growth and persistence of solid tumors. Their metastases, anti-angiogenesis could lead to the suppression of tumor growth. One of the main strategies of cancer treatment is developing molecules of anti-angiogenic activity. In this study, two angiogenic inhibitors, Ang3 (KLFDF) and Ang4 (XLFDF) derived from KLYDY, which is the sequence of angiostatin active sites kringle 5, were designed and synthesized. Previously we reported the activities and structures of two inhibitors, Ang1 (KLYDY) and Ang2 (KLWDF). In order to investigate the effect of Phe substitution, Ang3 was designed with a sequence of KLFDF. In order to reduce conformational flexibility of side chain in Lys, Ang4 was designed with a sequence of XLFDF, where X has amino substituted phenyl ring. Solution structures of those inhibitors were investigated using NMR spectroscopy and their activities as angiogenesis inhibitors were studied. Ang1 and Ang2 show angiogenic activities, while Ang3 and Ang4 have no activities and have extended structures compared to Ang1 and Ang2. Therefore, Phe rings do not have effective hydrophobic interactions with other aromatic residues in Ang3 and Ang4. The representative structure of Ang2 has a stable intramolecular hydrogen bond. Therefore, intramolecular hydrogen bonding might be more important in stabilizing the structure than the hydrophobic interactions in these inhibitors. More rigid structure, which can be expected to have higher activities and better match with the receptor bound conformations, can be obtained with a constrained cyclic structure. Further peptidomimetic approaches should be tried to develop angiogenesis inhibitors.

• 한국수산과학회지
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• 제35권6호
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• pp.686-695
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• 2002

Samples of Corbicula ( Corbicula) japonica Prime of Namdae Stream in Gangnung were collected from November 2000 to October 2001. Age of C. (C.) japonica was determined from the rings on the shell, The shell length of the samples ranged from 8 mm to 38 mm. The ring on the shell was formed once a year in March. Von Bertalanffy's growth parameters were estimated using a nonlinear regression method, asyinptotie shell length ($L_{\omega}$) was 48,98 mm, K was 0.20421year, theoretical age at 0 shell length $(t_0)$ was 0.3169 year, and asymptotic total weight ($W_{\omega}$) was 41.37 g. The formula of allomeky between shell length (L, mm) and total weight (W, g) of the brackish water clam was W=3.42$\times$10^{-4}L^{3}. The annual survival rate was estimated at 0.3799, instantaneous coefficient of natural mortality was 0.5007/year, and instantaneous coefficient of fishing mortality was 0.46721year. The age at first capture was estimated at 2.1593 year using shell length compositions of the brackish water clam, The current yield-per-recruit at 0.4672/year of fishing mortality was 0.6595 g. F_0.1 was estimated at 0.1865/year, Acceptable biological catch was estimated at 14.4 metric ton.

• Molecules and Cells
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• 제38권1호
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• pp.75-80
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• 2015

Osteoclasts are unique cells responsible for the resorption of bone matrix. MicroRNAs (miRNAs) are involved in the regulation of a wide range of physiological processes. Here, we examined the role of miR-26a in RANKL-induced osteoclastogenesis. The expression of miR-26a was upregulated by RANKL at the late stage of osteoclastogenesis. Ectopic expression of an miR-26a mimic in osteoclast precursor cells attenuated osteoclast formation, actin-ring formation, and bone resorption by suppressing the expression of connective tissue growth factor/CCN family 2 (CTGF/CCN2), which can promote osteoclast formation via upregulation of dendritic cell-specific transmembrane protein (DC-STAMP). On the other hand, overexpression of miR-26a inhibitor enhanced RANKL-induced osteoclast formation and function as well as CTGF expression. In addition, the inhibitory effect of miR-26a on osteoclast formation and function was prevented by treatment with recombinant CTGF. Collectively, our results suggest that miR-26a modulates osteoclast formation and function through the regulation of CTGF.

• Natural Product Sciences
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• 제25권1호
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• pp.38-43
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• 2019

Microbial wound infection prolonged the hospitalization and increase the cost for wound management. Silver is commonly used as antimicrobial wound dressing. However, it causes several adverse side effects. Hence, this study was aimed to evaluate the antimicrobial efficiency of Swietenia macrophylla seed extract on clinical wound pathogens. Besides, the bioactive constituents of the seed extract were also determined. S. macrophylla seeds were extracted with methanol by maceration method. The seed extract inhibited 5 test bacteria and 1 yeast on disc diffusion assay. The antibacterial activity was broad spectrum, as the extract inhibited both Gram positive and Gram negative bacteria. On kill curve analysis, the antibacterial activity of the seed extract was concentration-dependent, the increase of extract concentration resulted in more reduction of bacterial growth. The extract also caused 99.9% growth reduction of Bacillus subtilis relative to control. A total of 21 compounds were detected in gas chromatography- mass spectrometry analysis. The predominant compounds present in the extract were oleic acid (18.56%) and linoleic acid (17.72%). In conclusion, the methanolic extract of S. macrophylla seeds exhibited significant antimicrobial activity on clinical wound pathogens. Further investigations should be conducted to purify other bioactive compounds from the seeds of S. macrophylla.