• 제목/요약/키워드: Mexico

검색결과 638건 처리시간 0.036초

Analysis of Subwavelength Metal Hole Array Structure for the Enhancement of Quantum Dot Infrared Photodetectors

  • 하재두;황정우;강상우;노삼규;이상준;김종수
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
    • /
    • pp.334-334
    • /
    • 2013
  • In the past decade, the infrared detectors based on intersubband transition in quantum dots (QDs) have attracted much attention due to lower dark currents and increased lifetimes, which are in turn due a three-dimensional confinement and a reduction of scattering, respectively. In parallel, focal plane array development for infrared imaging has proceeded from the first to third generations (linear arrays, 2D arrays for staring systems, and large format with enhanced capabilities, respectively). For a step further towards the next generation of FPAs, it is envisioned that a two-dimensional metal hole array (2D-MHA) structures will improve the FPA structure by enhancing the coupling to photodetectors via local field engineering, and will enable wavelength filtering. In regard to the improved performance at certain wavelengths, it is worth pointing out the structural difference between previous 2D-MHA integrated front-illuminated single pixel devices and back-illuminated devices. Apart from the pixel linear dimension, it is a distinct difference that there is a metal cladding (composed of a number of metals for ohmic contact and the read-out integrated circuit hybridization) in the FPA between the heavily doped gallium arsenide used as the contact layer and the ROIC; on the contrary, the front-illuminated single pixel device consists of two heavily doped contact layers separated by the QD-absorber on a semi-infinite GaAs substrate. This paper is focused on analyzing the impact of a two dimensional metal hole array structure integrated to the back-illuminated quantum dots-in-a-well (DWELL) infrared photodetectors. The metal hole array consisting of subwavelength-circular holes penetrating gold layer (2DAu-CHA) provides the enhanced responsivity of DWELL infrared photodetector at certain wavelengths. The performance of 2D-Au-CHA is investigated by calculating the absorption of active layer in the DWELL structure using a finite integration technique. Simulation results show the enhanced electric fields (thereby increasing the absorption in the active layer) resulting from a surface plasmon, a guided mode, and Fabry-Perot resonances. Simulation method accomplished in this paper provides a generalized approach to optimize the design of any type of couplers integrated to infrared photodetectors.

  • PDF

시용 유기물을 달리한 토양에서 미생물 군락의 효소활성과 기능적 다양성의 계절적 변화 (Seasonal Dynamics of Enzymetic Activities and Functional Diversity in Soils under Different Organic Managements)

  • 박기춘
    • 한국토양비료학회지
    • /
    • 제42권4호
    • /
    • pp.307-316
    • /
    • 2009
  • 토양 개량을 위해 시용하는 유기물은 종류에 따라서 토양미생물 활성과 다양성에 미치는 영향을 다르며 그 효과는 계절적인 영향을 크게 받는다. 도시 가로수 폐기물 퇴비, 가금류 분뇨, 귀리와 레드 클로버의 피복작물이 토양 효소활성과 토양 미생물의 생리적 군락(CLPP) 특성에 미치는 영향을 미국 미주리 주의 사양토에서 조사하였다. 이들 토양 조사 항목들의 계절적 변화 패턴을 조사하기 위해서 2년간 봄부터 가을까지 토양을 매년 5회 채취하였다. 나무 폐기물 퇴비는 시용 3달 후부터 탈수소효소의 활성을 증가시키기 시작하였다. fluorescein diacetate (FDA) 수화도는 첫 해의 9월부터 증가하기 시작했으나 그 이후 변화가 심하였다. 탈수수효소의 활성은 FDA 소화도에 비하여 토양 유기물의 량이나 특성에 더 직접적으로 반응하였다. 반면에 FDA 수화도나 CLPP는 일반적으로 유기물의 구성 성분에 반응하였고, 효소활성과 CLPP 모두 계절에 따른 변화가 심하였다. 계절에 따른 변화는 유기물과 토양 수분함량의 차이에 기인한 것으로 보였다. 도시 가로수 폐기물 퇴비는 일반적인 토양 미생물 활성을 증가시키는데 효과적이었고 녹비는 토양 미생물 군락의 다양성을 변화시키는데 효과적이었다. 그리고 토양 미생물 활성과 다양성은 계절적 변화가 심하고 그 정도는 시용하는 유기물의 종류에 따라서 차이가 있으므로 토양의 미생물 특성을 조사할 때에는 작물의 재배기간 동안 여러 번 실시할 필요가 있다.

고립성 폐결절상을 보인 콕시디오이데스진균증 1예 (A Case of Coccidioidomycosis Manifested as Solitary Pulmonary Nodule)

  • 양현숙;이재천;임채만;이상도;고윤석;김우성;김동순;김원동;손광현;심태선
    • Tuberculosis and Respiratory Diseases
    • /
    • 제46권2호
    • /
    • pp.266-272
    • /
    • 1999
  • 콕시디오이데스진균증 토착 지역인 미국 애리조나 피닉스 지역을 여행한 과거력이 있는 국내 거주 75세 여자 환자에서 무증상의 고립성 폐결절로 악성종양을 의심하여 폐절제술을 시행한 결과 콕시디오이도마로 진단된 1예를 국내에서 처음 경험하였기에 보고 하는 바이다.

  • PDF

Observation of the Cosmic Near-Infrared Background with the CIBER rocket

  • 김민규;;이형목;;;;;;;;;이대희;;;;;남욱원
    • 천문학회보
    • /
    • 제37권1호
    • /
    • pp.42-42
    • /
    • 2012
  • The First stars (Pop.III stars) in the universe are expected to be formed between the recombination era at z - 1100 and the most distant quasar (z - 8). They have never been directly detected due to its faintness so far, but can be observed as a background radiation at around 1${\mu}m$ which is called the Cosmic Near-Infrared Background (CNB). Main part of the CNB is thought to be redshifted Lyman-alpha from gas clouds surrounding the Pop.III stars. Until now, the COBE (COsmic Background Explorer) and the IRTS (Infrared Telescope in Space) observed excess emission over the background due to galaxies. To confirm the COBE and the IRTS results and pursue more observational evidences, we carried out the sounding rocket experiment named the Cosmic Infrared Background ExpeRiment (CIBER). The CIBER is successfully launched on July 10, 2010 at White Sands Missile Range, New Mexico, USA. It consists of three kinds of instruments. We report the results obtained by LRS (Low Resolution Spectrometer) which is developed to fill the uncovered spectrum around 1${\mu}m$. LRS is a refractive telescope of 5.5 cm aperture with spectral resolution of 20 - 30 and wavelength coverage of 0.7 to 2.0${\mu}m$. After subtracting foreground components (zodiacal light, integrated star light and diffuse galactic light) from the sky brightness of observed five fields, there remained significant residual emission (even for the lower limit case) consistent with the IRTS and the COBE results. In addition, there exists a clear gap at 0.7 - 0.8${\mu}m$ in the CNB spectrum over the background due to galaxies according to recent results (Matsuoka et al. 2011; Mattila et al. 2011). The origin of the excess emission could be ascribed to the Pop.III stars with its active era of z = 7 - 10.

  • PDF

실세계 상황에서 수학적 모델링 과제설정 효과 (The Effects of Tasks Setting for Mathematical Modelling in the Complex Real Situation)

  • 신현성;이명화
    • 한국학교수학회논문집
    • /
    • 제14권4호
    • /
    • pp.423-442
    • /
    • 2011
  • 연구의 목적은 ICME(2008,Mexico) 모델링 TSG21에서 논의한 모델일의 두 과제 설정 MMa, MeA이 학교수학에 효율적으로 적용이 될 수 있는지를 알아보는데 있다. 이 실험에서 수학과 교육과정에 적용할 수 있는 몇 가지 중요한 점을 발견했는데, 첫째는 MMa집단이 통제집단 IPS에 모델링 문항에서 성취도에 우의미한 차이를 보였고, 정보처리 문항에서도 좋은 성취수준을 보였다. 다시 말하면 모델링 MMa, MeA 교육이 가능하게 현행 학교 문제 해결 또는 개념 학습에 포함이 되고 더욱 발전 되는 시스템을 가질 수 있다. 둘째는 실험집단의 학생들이 생성한 모델링 처음 3단계 상황분석, 수학질문 구성, 모델설정에서 독특한 발견전략을 사용하였고 후반 2단계에서도 전통적 IPS 문제해결과 좋은 연결성을 보였다. 또, 실험집단 MMa, MeA 학생들이 개념적 시스템의 구성과정을 잘 이해했으며 Lesh & Sriraman(2005a, 2005b)의 개념적 시스템의 구성을 뒷받침 해 주었다. 셋째는 과제설정 MMa, MeA 간에 모델링의 사고행동인 수학적 상황 센스를 만들기(S), 창조하기(C), 확장하기(E), 재정의하기(RF)가 교실에서 활발하게 일어났다는 점이다. 따라서 Pollak등이 제언한 모델링 활동은 현행 IPS 활동과 의미 있게 교류 될 수 있다.

  • PDF

비만 어린이와 청소년들의 체지방 평가를 위한 electronic pedometer 의 정확성 분석 (Accuracy of Electronic Pedometers to Assess Body Fatness in Obese Children and Youth)

  • 김도연
    • 생명과학회지
    • /
    • 제19권10호
    • /
    • pp.1368-1373
    • /
    • 2009
  • 본 연구는 미국 유타주에 거주하는 10-15세 어린이와 청소년들의 허리둘레가 electronic pedometer (전자 보수계)의 타당성과 신뢰성에 미치는 영향을 분석하기 위하여 비만집단 10명(HWC, BMI $28.91\pm3.07$)과 일반집단 10명 (LWC, BMI $18.05\pm1.55$)으로 총 20명(14 Hispanic and 6 Caucasian)의 어린이와 청소년들을 대상으로 실시하였다. Electronic pedometer 의 신뢰성을 측정하기 위하여 각 어린이는 Yamax SW-701 electronic pedometer 를 허리에 차고 15계단 오르기와 15계단 내리기를 3 sets 실시한 결과, HWC 집단이 LWC 집단보다 더 많은 보수를 기록했으나 오르기와 내르기 시행의 주 효과는 유의한 차이가 없었고, 또 두 집단간의 상호작용에도 유의한 차이가 없었다. 보수를 측정하여 pedometer의 타당성에 허리둘레가 미치는 영향을 분석하기 위하여 각자의 보행 속도에 따라 400 m를 걷게 한 결과 주 효과는 두 집단 간에 유의한 차이가 있었으나 counting technique (hand-counted vs. pedometer counted)의 주 효과는 유의한 차이가 없었으며, 또 400 m 걷기의 시기와 group별 시기의 상호작용도 유의한 차이가 없었다. 이러한 결과는 pedometer가 walking steps 측정에 HWC 집단과 LWC 집단에 동일하게 타당도가 있음을 나타내고 있다. 추후의 연구에서는 어린이들의 walking speed, pedometer tilt angle, leg length, 및 stride length 등을 고려한 연구가 필요하다고 사료된다.

말기의료에 관한 미국 법제의 연구 - 말기의료결정 제도를 중심으로 (Legislative Approaches to Terminal Care Issue in the U.S.A. - Acts on Terminal Health-Care Decision)

  • 석희태
    • 의료법학
    • /
    • 제14권1호
    • /
    • pp.355-401
    • /
    • 2013
  • The first legislation for terminal health-care decision was California's Natural Death Act (NDA) of 1976 that permitted any adult person to execute a directive directing the withholding or withdrawal of life-sustaining procedures. Advance directive legislation has subsequently progressed on a state-by-state basis. By 1992, all 50 states, as well as the District of Columbia, had passed legislation to legalize some form of advance directive. This state legislation, however, has resulted in an often fragmented, incomplete, and sometimes inconsistent set of rules. Statutes enacted within a state often conflict and conflicts between statutes of different states are common. In an increasingly mobile society where an advance health-care directive given in one state must frequently be implemented in another, there is a need for greater uniformity. In 1993, the Uniform Law Commissioners approved the Uniform Health-Care Decisions Act (UHCDA) in order to bring order to the existing chaos. Unfortunately, the Commissioners waited too long to act. By the time the UHCDA was approved, nearly all states had passed legislation governing advance directives. Consequently, the UHCDA has achieved only a limited success, picking up but one or two enactments a year. The UHCDA is currently in effect in around 10 states: Alabama, Alaska, California, Delaware, Hawaii, Kansas, Maine, Mississippi, New Mexico, Tennessee, Wyoming. In these states the previous laws related to the subjects have been all repealed. The overall objective of the UHCDA is to encourage the making and enforcement of advance health care directives including living will or individual instruction, power of health-care attorney and to provide a means for making health care decisions for those who have failed to plan. The U. S. House of Representatives in 1991 enacted the Patient Self-Determination Act (PSDA). The Act stipulates that all hospitals receiving Medicaid or Medicare reimbursement must ascertain whether patients have or wish to have advance directives. The Patient Self- Determination Act does not create or legalize advance directives; rather it validates their existence in each of the states. Now in America, terminal health-care decision or advance directive for health care is common and universal system. The problem, however, is how to let more people use these good tools to make their lives more beautiful and honorable.

  • PDF

Effect of stress during slaughter on carcass characteristics and meat quality in tropical beef cattle

  • Carrasco-Garcia, Apolo A.;Pardio-Sedas, Violeta T.;Leon-Banda, Gloria G.;Ahuja-Aguirre, Concepcion;Paredes-Ramos, Pedro;Hernandez-Cruz, Bertha C.;Murillo, Vicente Vega
    • Asian-Australasian Journal of Animal Sciences
    • /
    • 제33권10호
    • /
    • pp.1656-1665
    • /
    • 2020
  • Objective: This study aimed to determine the effects of stress during slaughter of beef cattle on physiological parameters, carcass, and meat quality at a Federal Inspection Type slaughterhouse located in the southeast of Mexico. Methods: A total of 448 carcasses of male Zebu×European steers with an average age of 36 months were included. Carcass assessment of presence of bruises and bruise characteristics was carried out on each half-carcass. Blood variable indicators of stress (packed cell volume, neutrophil to lymphocyte ratio, glucose, cortisol concentration) and meat quality parameters (pH, color, shear force, drip loss) were evaluated. Results: Of the 448 carcasses evaluated, 81% of the carcasses showed at least one bruise; one bruise was detected in 36.6% and two bruises in 27.0% of animals. Of the 775 bruises found, 69.2% of the bruises were grade 1 in region 3. Of the 448 carcasses studied, 69.6% showed hyperglycemia (6.91 mmol/L); 44.3% and 22.7% showed high (74.7 ng/mL) and extremely high (108.8 ng/mL) cortisol levels, respectively, indicative of inadequate handling of animals during preslaughter and slaughter. Of the carcasses evaluated, 90.4% had a pH ≥5.8 with an average of pH 6.3. In both pH groups, meat samples showed L values >37.0 (81.6%) and a shear force >54.3 N; meat pH≥5.8 group showed a drip loss of 2.5%. These findings were indicative of dark, firm, and dry (DFD) meat. According to principal component analysis, grades 1 and 2 bruises in region 3 and grade 1 bruises in region 5 were highly associated with cortisol, drip loss, and color parameters b and h and were negatively associated with L, a, and C. Conclusion: The bruises probably caused by stress-inducing situations triggered DFD meat. Appropriate changes in handling routines in operating conditions should be made to minimize stress to animals during the slaughter process to improve animal welfare and meat quality.

Motives, Strategies and Patterns of Foreign Direct Investment : The Case of Japanese and Korean Firms

  • Park, Kang-H.;Lim, Yong-Taek
    • 통상정보연구
    • /
    • 제7권4호
    • /
    • pp.387-407
    • /
    • 2005
  • This paper is to study globalization motives and strategies of Japanese and Korean industries by analyzing the causes and patterns of foreign direct investment (FDI) of the firms of the two countries during the 1980s and 1990s. First we develop a FDI function from the profit maximizing model of firms. Then we use regression analysis to determine internally driving-out factors and externally-inducing factors. Japanese FDI strategy has gone through three different stages; from natural resource-seeking investment in the 1950s and 1960s to market-expansion investment in the 1970s and 1980s and to a combination of cost-reducing (low-cost labor-seeking) investment and market-penetrating investment in the 1990s. On the other hand, Korean FDI behavior has gone through four different stages; from the learning stage with small investments in the 1970s, to natural resource-seeking investment in the early and mid 1980s, to the growth stage in the late 1980s and the early 1990s, to the maturity stage of the mid and late 1990s. The last two stages were characterized by a combination of cost-reducing investment and market-seeking investment. As a late comer, Korea began its FDI two decades later than Japan, but caught up the patterns of Japanese FDI by the mid 1990s and is in a competing position with Japan. Our findings show that both Japanese FDI and Korean FDI in Asia and other developing countries tendto be in labor-intensive sectors where their firms are losing their comparative advantages at home. The main motive for FDI into these regions is low-cost resource seeking. On the other hand, both Japanese FDI and Korean FDI in the U.S. and Europe tend to be knowledge-intensive sectors where Japanese and Korean firms attempt to internalize transaction and information costs by globalizing its production. The main motive for FDI into these regions is market-seeking. Firms in both countries have increased their investments in Mexico and Western and Eastern Europe in order to penetrate large economic blocs such as the EU and NAFTA area. Korean firms are more aggressive in expanding into new and untested markets than are their counterpart in Japan. Evidence of this can be seen in the scarcity of Japanese FDI and abundance of Korean FDI in Eastern Europe and China.

  • PDF

국내 비철금속 제련시설에서의 납 동위원소 배출특성 연구 (Characterization of lead isotope emission profiles in non-ferrous smelters in South Korea)

  • 박진주;김기준;박진수;유석민;박광수;석광설;신형선;송금주;김영희
    • 분석과학
    • /
    • 제26권5호
    • /
    • pp.333-339
    • /
    • 2013
  • 납 동위원소 분석은 국지적 및 지구적 납 오염 특성 해석을 위한 유용한 기법으로 널리 활용되어왔다. 본 연구는 국내 환경 중 납 오염원을 추적하기 위해 주요 배출원별 납 동위원소 인벤토리 구축사업의 일환으로 수행되었다. 특히 비철금속 제련시설은 가장 중요한 인위적 납 오염원으로 알려져 있으며, 본 연구에서는 국내에서 가동 중인 아연 (2 개 시설), 납 및 구리 제련시설에서의 납 동위원소의 유입 및 배출특성을 조사하였다. 각 제련시설에서 사용 중인 정광, 슬러지 및 폐수, 배출가스, 부산물로 생산되는 황산 및 제련된 금속제품 중의 납 농도와 납 동위원소 조성을 조사하였다. 아연 제련시설에서의 아연광석의 납 동위원소 분포는 1.179~1.198의 높은 $^{206}Pb/^{207}Pb$ 값을, 아연 제련시설에서 배출되는 배출가스, 제품, 폐기물 등은 1.105~1.147의 낮은 $^{206}Pb/^{207}Pb$ 값을 나타냈다. 국내 수입되는 아연광석은 주로 호주 및 페루 등이 주요 산지로서, 아연 제련시설에서 배출되는 물질들의 납 동위원소 분포는 중남미산 광석 및 호주산 광석의 납 동위원소 비율이 혼합된 것으로 추정되었다. 납 제련시설에서 배출되는 납 동위원소 패턴은 호주산 광석 및 중남미산 광석의 혼합 형태를 보이며, 구리 제련시설은 중남미 지역의 광석패턴을 따르는 것으로 추정되었다.