해양온도차발전 Closed and Regeneration Cycle의 기본 정특성

차상원(Sang1Won Cha),김유택(You1Taek Kim),이영호(Young1Ho Lee) 한국유체기계학회 2011 한국유체기계학회 학술대회 논문집 Vol.2011 No.11

Development of a T-DMB Monitoring System

Kyung-Taek Lee1,Ki-Won Kwon,Yong-Suk Park,Sung-Jun Kim,Jong-Ho Paik 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

With the start of T-DMB service, diverse multimedia broadcasting services became available in the high-speed mobile environment. In addition to high-quality digital radio (audio) and television (video), diverse data services, such as Dynamic Label Segment (DLS), JPEG Slideshow (SLS), Broadcast Web Site (BWS), Traffic and Travel Information (TTI), interactive service using Binary Format for Scenes (BIFS), and Visual Radio, are being serviced. Currently, there is an increase in demand in the market for T-DMB monitoring system that can support all the data service available. In this paper, we present T-DMB monitoring systems that can simultaneously decode 6 services of different format within the two ensemble, through suitable algorithms and multi-thread techniques.

기액 이상류시의 원심펌프특성에 관한 실험적 연구

김성윤,이상일,김유택,Kim, Sung-Yoon,Lee, Sang-Il,Kim, You-Taek 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.6

In a general centrifugal pump, if it is operated in a two-phase flow the activity of the impeller usually degrades and occasionally losses its function. However, the effect of break down of centrifugal pump due to entrained air has not been clarified yet. This paper shows the air-water two-phase flow characteristics of closed type and semi-open type impellers. In a sing1e-phase flow, closed-type impeller has higher efficiency and head. But in air-water two-phase flow semi-open type impeller's rates of decreases of efficiency and head are decreased.

제주도 지하수 질산염 농도의 시·공간적 변화 특성: 장기(1993-2015) 모니터링 자료의 평가

김호림(Ho-Rim Kim),오준섭(Junseop Oh),도현권(Hyun-Kwon Do),이경진(Kyung-Jin Lee),현익현(Ik-Hyun Hyun),오상실(Sang-Sil Oh),감상규(Sang-Kyu Kam),윤성택(Seong-Taek Yun) 대한자원환경지질학회 2018 자원환경지질 Vol.51 No.1

1993년부터 2015년까지 관측된 제주도 지하수 장기모니터링 관측정(N = 4,835)에서 수집된 지하수 수질자료(N = 21,568)를 기반으로 질산성질소의 시공간적 변동 특성을 평가하였다. 제주도 지하수의 질산성질소 농도의 중앙값은 2.5 mg/L로서 다른 국가나 대륙의 조사 결과에 비해 다소 높거나 유사한 것으로 나타났다. 또한 지하수 용도, 행정구역 및 고도 별로 유의한 차이를 보였다. 특히, 산간 지역에 비해 저지대 해안가에 위치한 농업 및 주거지역에서 농도가 높음을 확인하였다. Mann-Kendall 및 Sen’s slope 분석을 활용한 질산성질소 농도의 추세 분석 결과, 하류 저지 대에 비해 중산간지역에서의 질산성질소 농도 증가 경향이 뚜렷하였다. 제주도 내 토지 피복의 시계열 변화 특성과 결부 지어 보면, 중산간지역의 오염 증가 추세는 농업지역의 확장 등 인위적 활동 증가에 기인한 결과로 판단된다. 반면,기지정된 지하수자원특별관리구역에서는 전반적으로 질산성질소 농도의 감소 경향이 나타났는데, 이는 지하수 관리 측면에서 수질관리를 위한 적극적인 정책이 유효함을 시사한다. 본 연구에서는 제주도 지하수의 질산성질소 오염관리를 위한 적정 방안을 제안한다. The spatio-temporal variations of nitrate concentrations in groundwater of Jeju Island were evaluated by an analysis of time series groundwater quality data (N = 21,568) that were collected from regional groundwater monitoring (number of wells = 4,835) for up to 20 years between 1993 and 2015. The median concentration of NO 3 -N is 2.5 mg/L, which is slightly higher than those reported from regional surveys in other countries. Nitrate concentrations of groundwater in wells tend to significantly vary according to different water usage (of the well), administrative districts, and topographic elevations: nitrate level is higher in low-lying agricultural and residential areas than those in high mountainous areas. The Mann-Kendall trend test and Sen’s slope analysis show that nitrate concentration in mid-mountainous areas tends to increase, possibly due to the expansion of agricultural areas toward highland. On the other hand, nitrate concentrations in the Specially Designated Groundwater Quality Protection Zones show the temporally decreasing trend, which implies the efficiency of groundwater management actions in Jeju. Proper measures for sustainable groundwater quality management are suggested in this study.

A Dynamic Model of Humanoid Robots using the Analytical Method

Lee, Sang-Yong,Cho, Chang-Hyun,Choi, Mun-Taek,Kim, Mun-Sang,Kim, Jong-Won 한국정밀공학회 2010 International Journal of Precision Engineering and Vol.11 No.1

This paper presents a new approach to analyzing dynamic models of humanoid robots. This new approach is divided into an unconstrained system that applies the principle of Lagrangian dynamics and a constrained system that applies Gauss' principle. Constrained motion is important in the design and analysis of humanoid robots. In this paper, the central issue in the determination of the constrained system is considered to be the determination of this constraint factor. Using the fundamental equation described by the proposed approach, the constraint equation can easily be generated. Based upon the fundamental equation, the dynamic model of the humanoid robot is explained as divided by the sagittal and frontal planes. The suggested approach simplifies designing dynamic models of humanoid robots which will obey the constrained system whether or not they are constrained, holonomic, or open chain.

Receding horizon viability radius for stability of humanoid robot under external perturbation

Lee, Sang-Yong,Kim, Mun-Sang,Kim, Jong-Won,Choi, Mun-Taek 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.5

In this paper, a new approach that uses the rate of change of the angular momentum about the center of mass (COM) to improve the balance of a humanoid robot is proposed. This approach is motivated by how humans balance themselves when standing, walking, and running by making use of their upper body and swinging legs. Human movements such as lunging forward or backward and rotating arms make use of angular momentum to maintain balance. As the external perturbation increases, a human instinctively decides when and where to take a step to avoid a fall. In the same manner, a humanoid robot subjected to an external perturbation can determine whether to remain standing or to take a step with a swinging leg to maintain balance using RHVR conditions obtained from the proposed linear inverted dumbbell model. The rotation of a dumbbell model with mass inertia is an easy expression of the angular momentum of an upper body, arms, and legs. A zero-moment point (ZMP) outside the support polygon indicates an unbalanced gait and cannot represent a physical point related to the sole of the robot foot, which is defined as pseudo-ZMP (PZMP) in this paper. PZMP located outside the support area provides useful information for balancing the gait. PZMP from the foot edge provides a measure of the unbalanced moment that tends to rotate the humanoid robot around the supporting foot and causes it to fall. It is shown that PZMP is determined by the Gauss's principle within mechanical constraints of the rate of change of angular momentum about COM. In fact, the actual angular acceleration about COM is determined by the Gauss's principle. Additionally, RHVRs is defined, that is, viability regions to keep the balance that indicate the essential range of stability implemented to a real system. RHVRs are divided into the real ZMP (RZMP), PZMP and stepping PZMP (SPZMP). Hence, the regions of RHVR and the actual angular acceleration about COM determine which of the three control strategies is used.

How to avoid complications of distraction osteogenesis for first brachymetatarsia

Lee, Keun-Bae,Yang, Hyun-Kee,Chung, Jae-Yoon,Moon, Eun-Sun,Jung, Sung-Taek Informa Healthcare 2009 Acta orthopaedica Vol.80 No.2

<P><B>Background and purpose</B> Distraction osteogenesis may be used for the treatment of brachymetatarsia. However, few reports have been published on first metatarsal lengthening by this method. We evaluated the complications of distraction osteogenesis for first brachymetatarsia and here we provide a solution.</P><P><B>Patients and methods</B> 16 patients (27 feet) underwent distraction osteogenesis for first brachymetatarsia. Mean age at time of surgery was 20 (12–34) years and mean duration of postoperative follow-up was 5 (2–13) years. A unilateral external fixator was fixed at the medial aspect of the metatarsus. The distraction axis was parallel to the plantar surface of the foot in the sagittal plane and to the second metatarsal axis in the transversal plane.</P><P><B>Results</B> First metatarsal length expressed as a proportion of second metatarsal length was 60% (55–64). Average degree of metatarsal lengthening was 42% (34–54), and the average lengthening index was 64 (39–93) days/cm. The most common complication was stiffness of the metatarsophalangeal joint (12 feet). Deformities that included cavus foot and hallux valgus occurred in 3 feet each, and callus fractures occurred in 3 feet. The other complications were pin breakage and pin tract infection in 2 feet each.</P><P><B>Interpretation</B> Distraction osteogenesis for first brachymetatarsia can give satisfactory cosmetic and functional results. However, several complications are commonly encountered. This report on complications and their solutions may help those attempting distraction osteogenesis for first brachymetatarsia.</P>

Marine-Derived Secondary Metabolite, Griseusrazin A, Suppresses Inflammation through Heme Oxygenase-1 Induction in Activated RAW264.7 Macrophages

Lee, Dong-Sung,Yoon, Chi-Su,Jung, Yong-Taek,Yoon, Jung-Hoon,Kim, Youn-Chul,Oh, Hyuncheol American Chemical Society and American Society of 2016 Journal of natural products Vol.79 No.4

<P>A new secondary metabolite, named griseusrazin A (1), was isolated from the marine-derived bacterium Streptomyces griseus subsp. griseus. The structure of the compound was determined by analysis of spectroscopic data including MS, COSY, HSQC, HMBC, and N-15-RMBC data. Griseusrazin A (1) inhibited the production of inflammatory mediators, such as prostaglandin E-2 and nitric oxide, which was mediated through the suppression of the expression of cyclooxygenase-2 (COX-2) and t inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The production of pro-inflammatory cytokines, such as interleukin IL-1 beta, and tumor necrosis factor (TNF)-alpha, in the LPS-stimulated cells was also effectively blocked by griseusrazin A (1). Furthermore, this anti-inflammatory activity of 1 was linked to its inhibitory effects against the nuclear translocation of NF-kappa B p50 and p65, as wells as NF-kappa B binding activity. In the further study to elucidate the anti-inflammatory mechanism, 1 was shown to induce heme oxygenase-1 (HO-1) expression through the enhancement of nuclear translocation of nuclear factor E2-related factor 2. Furthermore, the anti-inflammatory activity of 1 in the LPS-stimulated cells was partially reversed by an HO inhibitor, tin protoporphyrin. These results indicate that the anti-inflammatory effect of 1 is associated with Nrf2-mediated HO-1 expression.</P>

Inhibition of Rac and Rac-linked functions by 8-oxo-2'-deoxyguanosine in murine macrophages.

Lee, Sun-Hye,Taek Han, Sang,Choi, Seong-Won,Sung, Seung-Yong,You, Ho-Jin,Ye, Sang-Kyu,Chung, Myung-Hee Harwood Academic ; Distributed by STBS Ltd 2009 Free radical research Vol.43 No.1

<P>Rac is a protein involved in the various functions of macrophages (Mphi), including the production of reactive oxygen species (ROS), phagocytosis, chemotaxis and the secretion of cytokines (such as gamma-INF). This study tested the effects of nucleosides containing 8-oxoguanine(8-hydroxyguanine) such as 8-oxo-2'-guanosine (8-oxoG) or 8-oxo-2'-deoxyguanosine (8-oxodG), on Rac and the above-listed Rac-associated functions of Mphi using mouse peritoneal Mphi (MpMphi). It is reported that 8-oxodG was able to effectively inhibit Rac and the Rac-associated functions of MpMphi. Compared to 8-oxodG, 8-oxoG showed negligible effects. Furthermore, normal nucleosides such as deoxyguanosine (dG), guanosine (G) and adenosine (A) did not exert any effects. These results suggest that 8-oxodG could be used as a potential tool to modulate the functions of Mphi that are intimately related to various pathological processes.</P>

Composition dependence of band gap energy of GaAsN alloys

Taek Sung Kim,C. -H. Hong,C. S. Park,E. -K. Suh,H. J. Lee,J. Y. Park,T. V. Cuong 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.2

The composition dependence of the band-gap energy of GaAs$_{1-x}$N$_x$ layers on GaAs substrates is studied by using photocurrent measurements and high-resolution X-ray diffraction. The GaAs$_{1-x}$N$_x$ alloys were grown using metalorganic chemical vapor deposition. The photocurrent spectra show clear near-band-edge peaks at 77 and 297 K, and the peak energies drastically decrease with increasing nitrogen composition due to band-gap bowing in the GaAs$_{1-x}$N$_x$ alloy. This result indicates that the bowing parameter reaches 25.39 eV for very low nitrogen incorporation ($x$ = 0.31 \%), and decreases with increasing nitrogen composition. An empirical double exponential composition dependence of the bowing parameter is presented.