• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.1
• /
• pp.99-104
• /
• 2013

In this paper, we developed a fully integrated downconverter MMIC (monolithic microwave integrated circuit) including Lange coupler and output active balun for millimeter wave applications. Concretely, ${\lambda}$/4 transmission line was added to Lange coupler for size reduction of RF/LO input, and mixed RF/LO signals were applied to gate of the FET of mixer. Active balun was used at output port for a coupling of out-of-phase IF output signals. According to measured results, the proposed downconverter MMIC showed good RF performances. For example, the downconverter MMIC showed an LO leakage power of -25 dBc at IF output port, and a RF-LO isolation of 18 dB. Therefore, off-chip components such as LO rejection filters were not required for a normal operation of the proposed downconverter MMIC. The proposed downconverter MMIC showed a conversion gain of 10.3 dB at RF frequency of 63 GHz. The size of the downconverter MMIC including all active and passive components was $2.2{\times}1.4mm^2$.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2003.11a
• /
• pp.309-310
• /
• 2003

입자상물질에 대한 연구는 광역적인 대기 오염정도의 평가 및 오염물질의 이동에 대한 유용한 정보를 제공해 주므로 이와 같은 오염원의 크기에 대한 배경농도를 파악하는 것이 무엇보다 중요하다. 또한 입자상물질은 대기중에서 기류를 타고 이동할 수 있기 때문에 오염농도 변화는 지역적인 영향을 받는 대도시 지역보다 오염원으로부터 격리된 청정지역에서의 측정이 필요하다(신혜정 등, 2002). 본 연구에서는 국내 배경농도 측정지점 중 하나인 강화에서 2000년부터 2002년까지 측정한 입자상 물질의 농도 특성을 파악하고자 한다. (중략)

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.4
• /
• pp.203-212
• /
• 2005

Anthropogenic emissions of greenhouse gases, particularly carbon dioxide($CO_2$) which arises mainly as wastes from the fossil fuel burning processes, are causing global warming. The effects of global warming become increasingly felt all over the world including sea level rise and extreme weather. The more direct consequences of the elevated atmospheric $CO_2$ on the ocean is the acidification of the surface ocean which brings a far reaching adverse impact on the life at sea and probably on the whole ecosystem of the planet. Improvement in energy efficiency and use of alternative energy sources are being made to reduce $CO_2$ emissions. However, a rapid transition to alternatives seems unachievable within a few decades due to the constraints on the associated technology and socio-economic factors in the world, since fossil fuels make up approximately 85% of the world's commercial energy demands. It has now been recognized that capture and geological sequestration of $CO_2$ could significantly reduce its emissions from fossil fuel utilization and therefore provides the means to rapidly achieve large reductions in $CO_2$ emissions(excerpts from London Convention, LC/SG 28, 2005). In Korea, well-developed sedimentary basins are spread over the vast continental shelf and slope regions, whereas, the land is densely populated and limited in area. Consequently, the offshore area is preferred to the land for the sites for geological sequestration. The utilization of the offshore area, however, may be subject to international agreements including London Convention. In this paper, the recent trends in technologies and regulations for $CO_2$ capture and geological sequestration are described to encourage its applications in Korea.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.1
• /
• pp.39-45
• /
• 2005

In the situation which Russia's ratification of the Kyoto protocol at February,2004, ANNEX I nations must reduce GHG(Green House Gas) discharge rate from 2008 by 2012 to the reduction level at 1990. We introduce the CO₂ ocean sequestration that is one of promising method for getting the stable CO₂ concentration in the atmosphere. There are four categories : ocean transportation technique, ocean initial dissolution technique, ocean deep current evaluation technique, and ocean biological evaluation technique. In this paper, we carried out the fundamental numerical study on the ocean initial dissolution technique, when the Liquidized CO₂ is emitted at the deep ocean, It is very important to the dissolution rate of movable CO₂ interface because it Is directly impact to the ocean organism. In order to investigate the relation of the interface movement and rate of the dissolution, we develope CR(Computational Fluid Dynamics) code that was constructed by the finite volume method based on the unstructured mesh, and a droplet's boundary surface can move and one direction dissolution from disperse phase into continuous phase adopted as its physics be. This study clarifies hydrodynamic relation between solubility and movement of the droplet through the verification of the Cm code.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.10
• /
• pp.31-39
• /
• 2004

This paper illustrates the noise characteristics under chip's core operations according to types of packages and modules for DDR DRAM For analyzing this, the impedance profiles and power noises are analyzed with DRAM chips having commercial TSOP package and commercial FBGA package on TSOP-based DIMM and FBGA-based DIMH In controversy with common concepts, we find that the noise-isolation characteristics of FBGA package are more weak and sensitive on transferred noises than those of the TSOP package. In addition, the simulated results show that the decoupling capacitor locations of modules are more important to control the self and transfer noise characteristics than the lead inductance of the packages. Therefore, satisfying the target spec of the noise suppression and isolation can be achieved through the design of power distribution systems only with considering not only the package types but also the whole module system.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2004.06a
• /
• pp.242-242
• /
• 2004

원자력발전소의 운전과정에서 계획적 혹은 비계획적으로 방출되는 미량의 입자상 방사성 물질들은 대부분 원전 부지내 토양에 침적되게 된다. 이러한 과정 속에서 오염토양이 발생하게 되면 수거되어 단순 격리관리하고 있는 실정이지만 앞으로 원전의 해체과정 등으로 인한 오염토양이 상당량 발생할 것으로 예상되기 때문에 적절한 제염을 통하여 폐기물량을 최소화시킬 필요가 있다. 이를 위해 오염토양 제염공정으로 물을 이용한 토양세척법을 선정하여 제염장치를 제작하였으며 실증시험을 수행하였다.(중략)

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2000.11a
• /
• pp.324-327
• /
• 2000

본 논문은 차세대 이동 통신인 IMT-2000(International Mobile Telecommunication-2000)용 기지국에 장착될 사용되어 질 이중 편파 다이버시티 안테나를 개발하는데 있다. 내용은 이중 편파 다이버시티를 이용한 안테나의 대역폭과 port간 격리도 및 방사 패턴을 설계와 제작을 통해 알아보았고, 안테나 후면에 전력 증폭기를 장착시키기 위하여 EIRP(Effective Isotropic Radiated Power)를 중심으로 송신 출력을 계산하고 이런 계산식을 바탕으로 전력 증폭기를 안테나 후면에 장착하여 실제 공간상에서 안테나를 통해 방사되는 출력 전력을 실험을 통해 알아보았다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.10a
• /
• pp.346-347
• /
• 2016

인프라로써의 전산자원은 사용자간에 공동 활용될 때 비용 효율을 얻을 수 있다. 이것은 web, was, dbms 중심의 기존 정보시스템 뿐 만 아니라 빅 데이터 등 분산처리가 요구되는 분야에서도 마찬가지이다. 분산처리 시스템에서 보안상 안전하게 전산 리소스를 공유하기 위한 요소를 살펴보고 사용자별로 격리된 클러스터를 제공하는 분산처리 공유 플랫폼을 구축하여 확인해 보았다.

• Journal of Chest Surgery
• /
• v.36 no.5
• /
• pp.356-362
• /
• 2003

Background: Intralobar and extralobar pulmonary sequestrations have been considered as congenital lesions that occur at different stages of embryonic life. However, most cases of intralobar pulmonary sequestration (IPS) seem to have an acquired origin, as they are absent in infants and associated anomalies are relatively, uncommon among them. Material and Method: The cases of 25 patients who were diagnosed as IPS after surgical resection from December, 1985 to July, 2002 were included in this study. The medical records wire retrospectively reviewed and the clinical characteristics were age at operation; gender; symptoms at presentation; presence of congenital anomalies; combined diseases; preoperative studies and diagnosis; location of the lesion; method of surgical resection; origin, size and numbers of aberrant artery; histopathological findings; and postoperative complications. Result: There were 17 (68%) female patients and 8 (32%) male patients, their ages ranged from 1 to 57 and mean value was 23 years old. Though 14 patients (56%) complained of respiratory symptoms such as pneumonia and recurrent respiratory infections, a large number of patients (44%) were asymptomatic or had chest pain only when the lesion was discovered. Only 8 patients (32%) were diagnosed as pulmonary sequestration preoperatively and 8 (32%) were suspected as mediastinal or lung tumor, 5 (20%) were congenital or acquired cystic lung disease, and 4 (16%) were lung abscess or bronchiectasis, respectively. The majority of aberrant arteries (86.4%) confirmed during the operation were originated from thoracic aorta and 2 were thoracic and abdominal aorta, 1 was abdominal aorta, respectively. The younger patients (less than 10 years old) had more other congenital anomalies (30% vs 6.7%) but the proportion of congenital IPS was not significantly different (10% vs 6.7%, p>0.05) compared with elder patients. Histopathologically, almost all lesions showed chronic inflammation, cystic changes and similar pleural adhesions regardless of age. Conclusion: The large portion of the patients with IPS (44%) was clinically asymptomatic or presented non-respiratory symptoms at diagnosis and likely to be diagnosed as mediastinal or lung tumor especially in elder patients. Though the younger patients had more other congenital anomalies, most cases of IPS proved to be acquired lesions in terms of the histopathlogical findings and the proportion of congenital evidences.

• Journal of Chest Surgery
• /
• v.34 no.3
• /
• pp.235-239
• /
• 2001

배경: 폐격리증, 선천성 낭성 유선종 기형, 기관지 낭종 선천성 엽기종 및 낭성 기관지 확장증 등의 폐에 발생하는 선청성 낭성 질환은 않으며 유사한 발생학적 및 임상적 양사을 가진다. 대상 및 방법: 1972년부터 1999년까지 본원 흉부외과에서 선청성 낭성 폐질환으로 수술받은 46명의 환자를 대상으로 병상 기록을 통한 임상상, 치료 및 병리소견을 검토하였다. 결과: 환자의 평균 연령은 16.2세 였고 남녀비는 17:29였다. 주 증상은 감염에 의한 발령이 11례, 호흡곤란이 10례 그리고 흉통과 가래 등이였고, 증상이 없었던 경우가 13례 였다. 질환은 폐격리증이 13례, 선청성 낭성 유선종 기형이 12례, 기관지성낭종이 12례, 낭성 기관지 확장증이 5례 그리고 선천성 엽기종이 4례였다. 수술은 단순 절계 8례, 폐구역 절제술 6례, 폐엽 절제술 31례 그리고 전폐 전제술 1례를 시행하였고 수술 사망은 폐엽 절제술은 시행한 7세된 기관지 낭종 환자로 수술직후 발생한 뇌경색으로 1례에서 발생하였으며 술후 합병증으로는 폐렴 4례와 지속적 공기누출과 농흉이 각 1례씩 이었다. 결론; 선청성 낭성 폐질환을 가진 환자들은 진단 즉시 수술하여 좋은 결과를 얻었다.