• 천문학회지
• /
• 제30권1호
• /
• pp.95-106
• /
• 1997

We investigate the velocity distribution of dark matter in the disk of a galaxy like the Milky Way at the solar radius. Using N-body simulations with the total mass and z-component of angular momentum conserved, we calculate the response of a dissipationless dark matter galactic halo during the dissipational collapse of the baryonic matter in spiral galaxy formation. The initial distribution of dark matter and baryonic particles is assumed to be a homogeneous mixture based on a King model. The baryonic matter is assumed to contract, forming the final luminous components of the galaxy, namely the disk and, in some cases, a bulge and central point. Both slow and fast growth of the luminous components are considered. We find that the velocity distribution of dark matter particles in a reference frame rotating slowly about the galaxy center in the plane of the disk is similar to a Maxwellian, but it is somewhat boxier, being flatter at the peak and truncated in the tails of the distribution. We tabulate parameters for the best-fitting Maxwellian and modified-Maxwellian distributions. There is no significant difference between slow collapse and fast collapse for all these results. We were unable to detect any effect of disk formation on the z-dependence of the dark matter density distribution.

• 한국통신학회논문지
• /
• 제28권6C호
• /
• pp.561-569
• /
• 2003

본 논문에서는 Alamouti［1］, Tarokh［14］, Xia［11］에 의해 도입된 직교 시공간 부호를 포함한 임의의 선형 직교 시공간 블록 부호에 대해, 느린 레일라이 페이딩 채널(slow Rayleigh fading channel)의 쌍간 오율(pairwise error probability)의 정확한 표현이 2개의 전송된 부호어 행렬(codeword matrices) 사이의 부호어 심볼 거리(codeword symbol distance)가 아니라, 2개의 메시지 벡터(messgae vector) 사이의 메시지 심볼 거리(message symbol distance)의 식으로 유도된다. 1차원 성분의 심볼 오율을 이용하여, 선형 직교 시공간 부호의 심볼 오율의 정확한 폐형의 표현이 QPSK, 16-QAM, 64-QAM과 256-QAM에 대해 유도된다.

• 대한구순구개열학회지
• /
• 제13권2호
• /
• pp.85-92
• /
• 2010

Vascular malformations (VMs) in the head and neck region are present at birth and grow commensurately with the child, they can result in significant cosmetic problems for the patient, and some may lead to even serious life threatening hemorrhage. Although the molecular mechanisms underlying the formation of these VMs remain unclear, lesions are known to result from abnormal development and morphogenesis. Histologically, there are no evidence of cellular proliferation, but rather progressive dilatation of abnormal channels, which VMs are designated to their prominent channel types such as capillary, venous, lymphatic, arterial, and combined malformations. VMs with an arterial component are rheologically fast-flow, whereas capillary, lymphatic, and venous components are slow-flow. In this article, we review the clinical presentations, diagnosis, and management of VMs of facial regions with author's embolization and surgical treatment cases.

• Journal of Advanced Marine Engineering and Technology
• /
• 제34권2호
• /
• pp.325-331
• /
• 2010

본 논문에서는 주기적 접지구조(PPGS)를 가지는 소형 단파장의 미앤더 선로를 GaAs MMIC(Monolithic Microwave Integrated Circuit) 상에 구현하였다. PPGS구조를 이용한 미앤더 선로는 기존의 미앤더 선로에 존재하던 용량 $C_a$와 함께 추가적인 용량 $C_b$를 가짐으로써 전체적인 용량이 커지게 되어, 단파장 특성을 보여주었다. 기존의 미앤더 선로는 주기적 구조가 아닌데 반해 PPGS 구조의 미앤더 선로는 주기적 구조이므로 $\beta$값이 큰 slow-wave가 존재하며, 이로 인해 종래의 미앤더 선로에 비해 선로 상에서 훨씬 더 큰 위상변화량을 보여준다. 본 논문에서는 상기 미앤더 선로의 특성을 실험적으로 고찰하여 PPGS 구조의 미앤더 선로를 병렬 인덕터로 사용할 경우, 기존 미앤더 선로를 사용할 때 보다 높은 인덕턴스 값을 가지므로 동일한 길이의 기존 선로보다 큰 인덕턴스 값을 가지는 정합 소자로써 사용할 수 있음을 확인하였다.

• 한국식품영양학회지
• /
• 제30권4호
• /
• pp.823-829
• /
• 2017

To increase the shelf-life of strawberry, samples were treated with two gel packs containing slow-released chlorine dioxide ($ClO_2$) gas at 3~5 ppm for 6 days at room temperature and the changes in the major chemical components (ascorbic acid, polyphenols, flavonoids and anthocyanin) contents and antioxidative activities (DPPH, ABTS radical scavenging and metal chelating activity) were investigated. The content of ascorbic acid of control was 40.38 mg% and contained 35.67~44.75 mg% during 6 days. There was no tendency to increase or decrease during storage period. The contents of ascorbic acid of control and 3~5 ppm $ClO_2$ gas treated samples were not significantly different during storage period. The content of polyphenol compounds of initial stage was 111.23 mg% and contained 117.78~132.40 mg% during 6 days. The contents of polyphenol compounds of 3~5 ppm $ClO_2$ gas treated samples were 103.51~130.25 mg%. There were no significant different between them during storage. The flavonoids and anthocyanin contents were not different from the control during storage period regardless of 3~5 ppm $ClO_2$ gas treatment. Furthermore, antioxidative activities were not different among the control and $ClO_2$ gas treatments during storage.

• 농업과학연구
• /
• 제5권2호
• /
• pp.56-67
• /
• 1978

본(本) 실험(實驗)은 대두(大豆)의 성숙중(成熟中) 종실(種實)의 발육(發育)과 단백질(蛋白質) 및 그 구성분(構成分)의 변화(變化)에 관한 고저단백질(高低蛋白質) 품종간(品種間)의 생리적(生理的) 차이를 밝히고자 고단백품종(高蛋白品種) 서해(西海)20호(號), 중단백품종(中蛋白品種) 광교(光敎) 및 저단백품종(低蛋白品種) Shelbv를 공시(供試)하여 종실(種實)의 발육상황(發育狀況), 단백질(蛋白質) 및 지방함량(脂肪含量) 변화(變化), disc polyacrylamide gel 전기영동법(電氣泳動法)에 의한 단백질구성분(蛋白質構成分)의 조성변화(組成變化) 등을 조사(調査)하였던 바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 대두(大豆) 종실(種實)은 대체(大體)로 개화후(開化後) 22일(日)까지 완만(緩慢)히 그 이후(以後) 20~30일간(日間) 직선적(直線的)으로 급속(急速)히, 그후 5~15일간(日間) 서서히 건물중(乾物中)이 증가(增加)되어 최고(最高)에 달하며, 개화후(開化後) 12일(日)부터 27일(日)까지 단백질함량(蛋白質含量)은 급속(急速)히 감소(減少)되는 반면에 지방함량(脂肪含量)은 급격(急激)히 증가(增加)되고 그 후부터 개화후(開化後) 40~47일(日)까지는 단백질(蛋白質)과 지방함량(脂肪含量) 모두 서서히 증가(增加)된 후 성숙기(成熟期)까지 큰 변화(變化)가 없었다. 2. 고단백품종(高蛋白品種) 서해(西海)20호(號)는 광교(光敎) 및 Shelby에 비해 전(全) 성숙기간(成熟期間)에 대한 비율(比率)로 보아 성숙초기(成熟初期)의 단백질(蛋白質) 함량(含量) 감소기간(減少期間)이 짧고 감소율(減少率)도 적었으며 그후 단백질함량(蛋白質含量) 증가기간(增加期間)이 길고 증가율(增加率)도 큰 특성(特性)을 보였으나, 지방(脂肪) 축적(蓄積)은 일찍 정지(停止)되었다. 3. 저단백(低蛋白) 고지방품종(高脂肪品種) Shelby는 서해(西海)20호(號) 및 광교(光敎)에 비해 전(全) 성숙기간(成熟期間)에 대한 단백질함량(蛋白質含量) 감소기간(減少期間)이 길고 증가기간(增加期間)은 짧았으며, 지방함량(脂肪含量)의 증가기간(增加期間)이 특히 길었다. 4. 종실(種實)의 성숙과정중(成熟過程中) 단백질구성분(蛋白質構成分)의 변화양상(變化樣相)은 품종간(品種間) 차(差)가 뚜렷하였고, 완숙종실(完熟種實)의 단백질구성분(蛋白質構成分)들이 모두 출현(出現)하는 시기(時期)는 종실(種實)의 단백질함량(蛋白質含量) 감소(減少)가 끝난 시기(時期)와 대체(大體)로 일치(一致)되었으며, 상대이동도(相對移動度)가 가장 작은 단백질(蛋白質)(a'=Rm 0.03)이 개화후(開花後) 17일(日)까지는 존재(存在)하였으나 그 이후(以後)에는 없었다. 5. 고단백품종(高蛋白品種) 서해(西海)20호(號)는 광교(光敎) 및 Shelby에 비해 단백질구성분(蛋白質構成分) a($a_1+a_2+a_3$)의 조성비율(組成比率)이 성숙초기(成熟初期)에서부터 계속 높았고 개화후(開花後) 47일(日)까지 계속 증가(增加)되었으나, 광교(光敎)와 Shelby에서는 구성분(構成分) a의 조성비율(組成比率)이 개화후(開花後) 27일경(日頃) 이후(以後) 거의 변화(變化)되지 않았다.

• 드라이브 ㆍ 컨트롤
• /
• 제16권4호
• /
• pp.1-8
• /
• 2019

The HPM (High-speed Power Matching) system is an electro-hydraulic control system. It directly controls the swash plate of the pump by selecting four-loop logic based on joystick signals, pump flow, and pressure signal to improve the efficiency and controllability of construction machines. In the NFC (Negative Flow Control) system, a typical pump control system using conventional open center type MCV, the loss is continuously generated by flow through the center bypass line even when the excavator is not in operation. Also, due to the slow response of the pump that indirectly controls the flow rate using the pressure regulator, peak pressure occurs at the start or stop of the operation. Conversely, the HPM system uses an MCV without center-by-pass flow path and the swash plate of a pump for the HPM is controlled by a high-speed proportional flow control valve. As a result, the HPM system minimizes energy loss in standby state of the excavator and enables peak pressure control through rapid electro-hydraulic control of a pump. In this paper, the concept of the HPM system algorithm is introduced and the hydraulic system efficiency is compared with the NFC system using the excavator SAT (System Analysis Tool).

• Bulletin of the Korean Chemical Society
• /
• 제32권2호
• /
• pp.583-589
• /
• 2011

Fluorescence correlation spectroscopy (FCS) is a sophisticated and an accurate analytical technique used to study the diffusion of molecules in a solution at the single-molecule level. FCS is strongly affected by many factors such as the stability of the excitation power, photochemical processes, mismatch between the refractive indices, and variations in the cover glass thickness. We have studied FCS near the surface of a cover glass by using rhodamine 123 as a fluorescent probe and have observed that the surface has a strong influence on the measurements. The temporal autocorrelation of FCS decays with two characteristic times when the confocal detection volume is positioned near the surface of the cover glass. As the position of the detection volume is moved away from the surface, the FCS autocorrelation becomes one-component decaying; the characteristic time of the decay is the same as the faster-decaying component in the FCS autocorrelation near the surface. This observation suggests that the faster component can be attributed to the free diffusion of the probe molecules in the solution, while the slow component has its origin from the interaction between the probe molecules and the surface. We have characterized the surface contribution to the FCS measurements near the surface by changing the position of the detection volume relative to the surface. The influence of the surface on the diffusion of the probe molecules was monitored by changing the chemical properties of the surface. The surface contribution to the temporal autocorrelation of the FCS strongly depends on the chemical nature of the surface. The hydrophobicity of the surface is a major factor determining the surface influence on the free diffusion of the probe molecules near the surface.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권8호
• /
• pp.3884-3910
• /
• 2016

Intrusion Detection System (IDS) in general considers a big amount of data that are highly redundant and irrelevant. This trait causes slow instruction, assessment procedures, high resource consumption and poor detection rate. Due to their expensive computational requirements during both training and detection, IDSs are mostly ineffective for real-time anomaly detection. This paper proposes a dimensionality reduction technique that is able to enhance the performance of IDSs up to constant time O(1) based on the Principle Component Analysis (PCA). Furthermore, the present study offers a feature selection approach for identifying major components in real time. The PCA algorithm transforms high-dimensional feature vectors into a low-dimensional feature space, which is used to determine the optimum volume of factors. The proposed approach was assessed using HTTP packet payload of ISCX 2012 IDS and DARPA 1999 dataset. The experimental outcome demonstrated that our proposed anomaly detection achieved promising results with 97% detection rate with 1.2% false positive rate for ISCX 2012 dataset and 100% detection rate with 0.06% false positive rate for DARPA 1999 dataset. Our proposed anomaly detection also achieved comparable performance in terms of computational complexity when compared to three state-of-the-art anomaly detection systems.

• 한국염색가공학회지
• /
• 제14권4호
• /
• pp.229-239
• /
• 2002

Colorants were extracted from the heartwood of sappan lin. with MeOH under reflux, and the concentrate or the powder of dye was prepared by low pressure concentration method using suitable organic solvent. Various components were isolated from sappan wood, and the chemical structure and mechanism of compound having the excellent antibacterial and deodorization properties were analyzed. The results obtained are as follows ; The seventeen components of sappan wood were seperated by HPLC chromatography, and the five components among them were existed more than 6% and the other components were existed lower than 0.6%. The resolving powers of the non-polar solvent and polar solvent systems were evaluated by their ability to resolve the samples. It showed that chloroform-methanol-water(800:150:10) system has the best resolving power. Although the seperation rate is very slow, polyamide C-100 column chromatography gives a clear seperation of sappan wood. On the basis of the spectrometric data such as IR, UV, $GC-Mass,\;^1H-NMR,\;^{13}C-NMR\;and\;^1H-^{ 13}C-NMR$, the chemical structure of compound haying the excellent antibacterial and deodorization properties was established as brazilin containing the functional groups such as two quaternary carbon, one benzyl carbon, methylene contiguous to oxygen and methylene caused by oxygen atom.