• 한국해양공학회지
• /
• 제34권5호
• /
• pp.285-293
• /
• 2020

This study evaluated the Hook-up installation of an offshore site construction process, which is the final step in an offshore site installation process. During Hook-up installation, the offshore structure can have a detrimental effect on the work stability due to low-frequency motion. Moreover, economic costs can be incurred by the increase in available days of a tugboat. Therefore, this study developed a numerical analysis program to assess the dynamic behavior of mooring systems during hook-up installation to analyze the generally performed installation process and determine when the tugboat should be released. In this program, the behavior of an offshore structure was calculated using Cummin's time-domain motion equation, and the mooring system was calculated by Lumped mass method (LMM). In addition, a tugboat algorithm for hook-up installation was developed to apply the Hook-up procedure. The model used in the calculations was the barge type assuming FPSO (Floating production storage and off-loading) and has a taut mooring system connected to 16 mooring lines. The results of the simulation were verified by comparing with both MOSES, which is a commercial program, and a calculation method for restoring coefficient matrix, which was introduced by Patel and Lynch (1982). Finally, the offset of the structure according to the number of tugboats was calculated using the hook-up simulation, and the significant value was used to represent the calculation result.

• 대한원격탐사학회지
• /
• 제21권1호
• /
• pp.73-81
• /
• 2005

We construct improved geocentric digital elevation model (DEM), estimate tidal dynamics and ice stream velocity over Sulzberger Ice Shelf, West Antarctica employing differential interferograms from 12 ERS tandem mission Synthetic Aperture Radar (SAR) images acquired in austral fall of 1996. Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry profiles acquired in the same season as the SAR scenes in 2004 are used as ground control points (GCPs) for Interferometric SAR (InSAR) DEM generation. 20 additional ICESat profiles acquired in 2003-2004 are then used to assess the accuracy of the DEM. The vertical accuracy of the OEM is estimated by comparing elevations with laser altimetry data from ICESat. The mean height difference between all ICESat data and DEM is -0.57m with a standard deviation of 5.88m. We demonstrate that ICESat elevations can be successfully used as GCPs to improve the accuracy of an InSAR derived DEM. In addition, the magnitude and the direction of tidal changes estimated from interferogram are compared with those predicted tidal differences from four ocean tide models. Tidal deformation measured in InSAR is -16.7cm and it agrees well within 3cm with predicted ones from tide models. Lastly, ice surface velocity is estimated by combining speckle matching technique and InSAR line-of-sight measurement. This study shows that the maximum speed and mean speed are 509 m/yr and 131 m/yr, respectively. Our results can be useful for the mass balance study in this area and sea level change.

• 약학회지
• /
• 제48권3호
• /
• pp.189-196
• /
• 2004

Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) playa key role in tumor invasion and metastasis. As an inhibitor of MMP-2, TIMP-2 is known to block both the invasive and metastatic behavior of cancer cells, and decrease tumor growth activity. We performed this study to investigate the effects of TIMP-2 over-expression induced by retroviral mediated gene transfer in vitro and in vivo. The human colon cancer cell line SW480 was transfected with the retroviral vector encoding TIMP-2. The effects of TIMP-2 over-expression were analyzed by invasion assay and gelatinase activity test in colon cancer cells and tumorigencity in nude mice. In evaluation of the transfection efficiency of the retroviral vector encoding TIMP-2 in colon cancer cells, we confirmed up-regulation of TIMP-2 expression dependent on the time of cell culture. In addition, inhibition of MMP-2 expression in SW480/TIMP-2 was shown by gelatin zymography. In the in vitro invasion assay SW480/TIMP-2 inhibited the invasiveness on matrigel coated with collagen. To determine whether TIMP-2 can modulate in vivo tumorigenicity and metastasis, SW480/TIMP-2 cells were injected subcutaneously in nude mice. The tumor mass formation of SW480/TIMP-2 cells in nude mice was markedly decreased compared to nontransfected cancer cells. These results showed that colon cancer cells transfected with the retroviral vector encoding TIMP-2 inhibits the invasiveness in vitro and tumorigenicity in vivo.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 추계학술대회 논문집
• /
• pp.66-72
• /
• 2008

본 연구에서는 대심도 지하역사에서 화재가 발생할 시 급/배기 팬의 동작 유무에 따른 승강장에서의 열 및 연기의 거시적인 거동을 화재시뮬레이션을 통하여 분석하였다. 시뮬레이션 분석결과를 토대로 현재 설치된 급/배기 팬에 대한 제연/배연능력에 대하여 고찰하였다. 본 연구의 대상은 숭실대 입구 역사(7호선, 도시철도공사운영)이며, 숭실대 역사의 승강장은 길이 165m, 폭 23.5m, 깊이 47m 이다. 본 연구에서 전산수치해석을 위한 모델은 선로부 지하터널를 감안하여 전후 각 100m를 추가하였다. 따라서 모델링의 크기는 길이 365m, 폭23.5m, 깊이 47m 이다. 격자는 육면체 정렬격자계를 사용하였으며, 격자의 수는 대략 10,000,000 개가 사용되었다. 빠른 수치전산처리를 위하여, 병렬처리기법을 적용하였다. 본 전산수치해석에 사용된 CPU자원에 Intel 3.0GHZ Dual CPU 6개(core 12개)가 사용되었다.

• 설비공학논문집
• /
• 제12권1호
• /
• pp.50-58
• /
• 2000

Experiments were carried out to obtain the effects of nozzle configuration and jet to jet spacing on the heat transfer characteristics of single line of circular water jets impinging on a constant heat flux plane surface. The nozzle configurations are Cone type, Reverse cone type and Vertical circular type, and the nozzle arrays are single jet(nozzle dia. 8 mm), 1 row of 3 jets and 1 row of 5 jets. Jet velocities ranging from 3m/s to 8m/s were investigated for the nozzle to target plate spacing of 80 mm. For the Cone and Reverse cone type nozzle arrays, the average Nusselt number of 1 row of 5 jets was larger than that of 1 row of 3 jets at Re$_{D}$<45000, but that of 1 row of 3 jets was larger than that of 1 row of 5 jets at $Reo\le45000$. For the Vertical circular type nozzle, however, the average Nusselt number of 1 row of 3 jets was larger than that of 1 row of 5 jets at all jet velocities. In the condition of fixed mass flow rates, the maximum heat transfer augmentation was obtained for 1 row of 5 jets and was over 2 times larger than that of the single jet for all nozzle configurations. The nozzle configurations that produce the maximum average Nusselt number are as follows: For 1 row of 3 jets, the Vertical circular type at $Reo\le45000$ and the Reverse cone type at $Reo\le45000$. But, they are the Reverse cone type at Re$_{D}$<55000 and the Vertical circular type at$Reo\le55000$ for 1 row of 5 jets.

• 한국ITS학회 논문지
• /
• 제20권5호
• /
• pp.1-17
• /
• 2021

대부분의 도시철도 시스템은 승객의 탑승열차 및 탑승열차종을 정확히 알 수 없다. 다수의 선행연구에서는 교통카드데이터와 열차시각표를 매칭하여 탑승열차를 추정하였으나, 추정이 불가능한 승객 또한 다수 존재한다. 본 연구의 9호선 사례분석 결과 교통카드데이터-열차시각표 매칭만으로는 약 28% 승객의 탑승열차종을 추정할 수 없음을 확인할 수 있었다. 이에 교통카드데이터-열차시각표 매칭과 본 연구에서 정의한 통행시간 기반 혼합확률분포분석을 순차적으로 적용하여 급행운영 도시철도노선 승객의 탑승열차종을 추정하는 방법을 개발하였다. 분석 결과, 298개 OD pair에서 본 연구의 검증 기준을 만족하는 합리적인 급행이용/비이용 승객 분류기준점을 도출할 수 있었다.

• 한국응용과학기술학회지
• /
• 제35권4호
• /
• pp.1386-1392
• /
• 2018

시스플라틴은 지난 몇 십년간 가장 많이 사용되고 있는 항암제 중 하나이다. 2가의 시스플라틴의 가장 큰 단점은 암세포 뿐만 아니라 정상세포도 공격하여 부작용을 나타낸다. 본 연구에서는 이러한 단점을 줄이기 위해 목표로 한 타겟을 공격하여 빠른 시간 내에 암세포를 죽일 수 있는 4가의 백금화합물 3과 4를 합성하였다. 합성된 $Pt(IV)-Bu_2$ 3 and $Pt(IV)-Val_2$ 4는 NMR과 질량분석기를 통하여 구조를 확인하였다. 합성된 Pt(IV) 화합물 3과 4는 위암세포주인 MCF-7을 대상으로 한 MTT assay를 통해 항암효과를 조사하였다. 그 결과 시스플라틴은 39%, $Pt(IV)-Bu_2$ 3와 $Pt(IV)-Val_2$ 4는 $50{\mu}M$ 농도에서 각각 54%와 84%의 세포사멸을 보였다.

• Natural Product Sciences
• /
• 제24권4호
• /
• pp.235-240
• /
• 2018

Betula platyphylla var. japonica (Betulaceae), also known as Asian white birch, is an endemic medicinal tree, the bark of which has been used in Chinese traditional medicine for the treatment of various inflammatory diseases. In our continuing search for bioactive compounds from Korean natural resources, a phytochemical investigation of the bark of B. platyphylla var. japonica led to the isolation of 7-oxo-${\beta}$-sitosterol (1) and soyacerebroside I (2) from its ethanol extract as main components by liquid chromatography (LC)/mass spectrometry (MS)-based analysis. The structures of isolates were identified by comparison of $^1H$ and $^{13}C$ nuclear magnetic resonance spectroscopic data and physical data with the previously reported values and LC/MS analyses. To the best of our knowledge, this is the first study to demonstrate that the isolated compounds, 7-oxo-${\beta}$-sitosterol and soyacerebroside I, were isolated in B. platyphylla var. japonica. We examined the effects of the isolates on the regulation of adipocytes and osteoblast differentiation. These isolates (1 and 2) produced fewer lipid droplets compared to the untreated negative control in Oil Red O staining of the mouse mesenchymal stem cell line without altering the amount of alkaline phosphatase staining. The results demonstrated that both compounds showed marginal inhibitory effects on adipocyte differentiation but did not affect osteoblast differentiation.

• Geomechanics and Engineering
• /
• 제16권6호
• /
• pp.643-654
• /
• 2018

Tunnel excavation leads to a disturbance on the initial stress balance of surrounding soils, which causes convergences around the tunnel and settlements at the ground surface. Considering the effective impact of settlements on the structures at the surface, it is necessary to estimate them, especially in urban areas. In the present study, ground settlements due to the excavation of East-West Line 7 of the Tehran Metro (EWL7) and the Abuzar tunnels are evaluated and the effect of the lateral earth pressure coefficient ($K_0$) on their extension is investigated. The excavation of the tunnels was performed by TBMs (Tunnel Boring Machines). The coefficient of lateral earth pressure ($K_0$) is one of the most important geotechnical parameters for tunnel design and is greatly influenced by the geological characteristics of the surrounding soil mass along the tunnel route. The real (in-situ) settlements of the ground surface were measured experimentally using leveling methods along the studied tunnels and the results were compared with evaluated settlements obtained from both semi-empirical and numerical methods (using the finite difference software FLAC3D). The comparisons permitted to show that the adopted numerical models can effectively be used to predict settlements induced by a tunnel excavation. Then a numerical parametric study was conducted to show the influence of the $K_0$ values on the ground settlements. Numerical investigations also showed that the shapes of settlement trough of the studied tunnels, in a transverse section, are not similar because of their different diameters and depths of the tunnels.

• Biomolecules & Therapeutics
• /
• 제27권2호
• /
• pp.193-200
• /
• 2019

Ceramide metabolism is known to be an essential etiology for various diseases, such as atopic dermatitis and Gaucher disease. Glucosylceramide synthase (GCS) is a key enzyme for the synthesis of glucosylceramide (GlcCer), which is a main ceramide metabolism pathway in mammalian cells. In this article, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine GCS activity using synthetic non-natural sphingolipid C8-ceramide as a substrate. The reaction products, C8-GlcCer for GCS, could be separated on a C18 column by reverse-phase high-performance liquid chromatography (HPLC). Quantification was conducted using the multiple reaction monitoring (MRM) mode to monitor the precursor-to-product ion transitions of m/z $588.6{\rightarrow}264.4$ for C8-GlcCer at positive ionization mode. The calibration curve was established over the range of 0.625-160 ng/mL, and the correlation coefficient was larger than 0.999. This method was successfully applied to detect GCS in the human hepatocellular carcinoma cell line (HepG2 cells) and mouse peripheral blood mononuclear cells. We also evaluated the inhibition degree of a known GCS inhibitor 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) on GCS enzymatic activity and proved that this method could be successfully applied to GCS inhibitor screening of preventive and therapeutic drugs for ceramide metabolism diseases, such as atopic dermatitis and Gaucher disease.