• 한국전자파학회논문지
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• 제24권8호
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• pp.798-804
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• 2013

본 논문에서는 고주파 회로 모델링을 이용하여 전기자동차의 LDC로부터 방출되는 전도성 전자파 잡음을 시스템-레벨에서 분석하였다. 관련 전도 방출의 주요 원인은 LDC에서 사용하는 펄스폭 변조 방식의 100 kHz 스위칭 동작에 기인하며, 이러한 전도 방출은 공통-임피던스 결합 및 유도성 결합을 통해 AM/FM 주파수 대역에서의 무선주파수 간섭을 유발한다. 이러한 문제를 분석하기 위해 LDC를 구성하고 있는 MOSFET과 고압 커패시터, 고전압 케이블과 버스 바에 대한 기본 회로는 물론, 각 부분에서 존재하는 기생 성분 및 비선형 특성을 해석하여 LDC 전체를 포함한 시스템-레벨의 고주파 등가회로 모델을 제안하였다. 이러한 모델을 이용하여 시뮬레이션과 측정을 비교하여 유사성을 검증하였다. 향후 이러한 접근 방법이 전기자동차의 전자파 적합성 설계에 효과적으로 사용될 수 있을 것으로 기대한다.

• 산업기술연구
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• 제40권1호
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• pp.13-18
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• 2020

Lithium-ion batteries have a small volume, light weight and high energy density, maximizing the utilization of mobile devices. It is widely used for various purposes such as electric bicycles and scooters (e-Mobility), mass energy storage (ESS), and electric and hybrid vehicles. To date, lithium-ion batteries have grown to focus on increasing energy density and reducing production costs in line with the required capacity. However, the research and development level of lithium-ion batteries seems to have reached the limit in terms of energy density. In addition, the charging time is an important factor for using lithium-ion batteries. Therefore, it was urgent to develop a high-speed charger to shorten the charging time. In this thesis, a discharger was fabricated to evaluate the capacity and characteristics of Li-ion battery pack which can be used for e-mobility. To achieve this, a smart discharger is designed with a combination of active load, current sensor, and temperature sensor. To carry out this thesis, an active load switching using sensor control circuit, signal processing circuit, and FET was designed and manufactured as hardware with the characteristics of active discharger. And as software for controlling the hardware of the active discharger, a Raspberry Pi control device and a touch screen program were designed. The developed discharger is designed to change the 600W capacity battery in the form of active load.

• 마이크로전자및패키징학회지
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• 제21권3호
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• pp.7-17
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• 2014

Power electronics modules are semiconductor components that are widely used in airplanes, trains, automobiles, and energy generation and conversion facilities. In particular, insulated gate bipolar transistors(IGBT) have been widely utilized in high power and fast switching applications for power management including power supplies, uninterruptible power systems, and AC/DC converters. In these days, IGBT are the predominant power semiconductors for high current applications in electrical and hybrid vehicles application. In these application environments, the physical conditions are often severe with strong electric currents, high voltage, high temperature, high humidity, and vibrations. Therefore, IGBT module packages involves a number of challenges for the design engineer in terms of reliability. Thermal and thermal-mechanical management are critical for power electronics modules. The failure mechanisms that limit the number of power cycles are caused by the coefficient of thermal expansion mismatch between the materials used in the IGBT modules. All interfaces in the module could be locations for potential failures. Therefore, a proper thermal design where the temperature does not exceed an allowable limit of the devices has been a key factor in developing IGBT modules. In this paper, we discussed the effects of various package materials on heat dissipation and thermal management, as well as recent technology of the new package materials.

• International Journal of Automotive Technology
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• 제4권2호
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• pp.65-75
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• 2003

A HEV evaluation program, funded by ADEME, was carried out by a group of Laboratories of different specialties in order to evaluate and compare consumption, emission and component technologies of the three first HEVs put on the market (Toyota Prius, Nissan Tino and Honda Insight). This paper presents the results obtained until now. These results show good consumption and emission performance of the tested vehicles compared to conventional ones. The energy management seems to be globally the same for the three vehicles excepting for cold stans where the Insight allows a very earlier stop of the engine compared to the Tino and especially to the Prius. A mapping of the engine consumption of the Prius and the Insight was performed in order to furnish data for the simulation models. The Permanent Magnet motors of the Prius and Tino have different number of pair poles and then different emf at a given speed. The low emf values of the Prius allow operation at high speed with less field weakening control than for the Tino. The inverters of the Prius and the Tino, controlled by a PWM at respectively 5 kHz and 7 kHz switching frequency, are made of IGBTs with high commutation performances.

• 센서학회지
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• 제5권1호
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• pp.43-50
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• 1996

본 논문은 $1.5{\mu}m$ n-well CMOS 공정 기술에 의해 제조된 다중 바이오텔레미트리 시스템의 동작 특성을 기술하였다. 이 시스템은 체내에 삽입된 서로 다른 센서로부터 계측한 생체 정보를 무선으로 전송하여 외부에서 수신하는 것으로 8개의 피측정체로부터 선택된 7개의 생체 신호를 연속적으로 체외로 전송 한다. FM송신기와 센서 인터페이스 회로를 제외한 체내 삽입 시스템은 $4{\times}4mm^{2}$의 크기로 집적화 하였고, 집적 화한 IC는 $3{\times}3{\times}2.5cm$의 하이브리드 패키지에 수용하였다. 이 시스템의 특징은 8개의 피측정체중에서 임의의 피측정체를 선택할 수 있을 뿐 아니라, 외부 시스템의 커맨드 신호와 선택 신호에 의해 체내 삽입된 전원의 ON/OFF가 가능하다. 이와 같은 전원의 간헐적 동작으로 커맨드 수신기 자체의 소비 전력도 줄일 수 있다. 현재 국내에서 개발되고 있는 각종센서를 이 시스템과 결합해서 삽입하면 혈압 ECG, EMG, 체온 등의 생체정보를 측정하고 분석하는데 매우 편리할 것으로 기대한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.77.1-77.1
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• 2013

Atomic layer deposition (ALD) is known for its self-limiting reaction, which offers atomic-level controllability of the growth of thin films for a wide range of applications. The self-limiting mechanism leads to very useful properties, such as excellent uniformity over a large area and superior conformality on complex structures. These unique features of ALD provide promising opportunities for future electronics. Although the ALD of Al2O3 film (using trimethyl-aluminum and water as a metal precursor and oxygen source, respectively) can be regarded as a representative example of an ideal ALD based on the completely self-limiting reaction, there are many cases deviating from the ideal ALD reaction in recently developed ALD processes. The nonconventional aspects of the ALD reactions may strongly influence the various properties of the functional materials grown by ALD, and the lack of comprehension of these aspects has made ALD difficult to control. In this respect, several dominant factors that complicate ALD reactions, including the types of metal precursors, non-metal precursors (oxygen sources or reducing agents), and substrates, will be discussed in this presentation. Several functional materials for future electronics, such as higher-k dielectrics (TiO2, SrTiO3) for DRAM application, and resistive switching materials (NiO) for RRAM application, will be addressed in this talk. Unwanted supply of oxygen atoms from the substrate or other component oxide to the incoming precursors during the precursor pulse step, and outward diffusion of substrate atoms to the growing film surface even during the steady-state growth influenced the growth, crystal structure, and properties of the various films.

• 한국대기환경학회지
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• 제33권6호
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• pp.570-582
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• 2017

In recent years, national and local government's air quality management and climate change adaptation policy has been significantly strengthened. The measures in the two policies may be in a relationship of trade-off or synergy to each other. Greenhouse gases and air pollutants are mostly emitted from the same sources of using considerable amounts of fossil fuels. Co-benefits, in which either measure has a positive effect on the other, may be maximized by reducing the social costs and by consolidating the objectives of the various policies. In this study, the co-benefits were examined by empirically analyzing the effects of air pollutants and greenhouse gas emission reduction, social cost, and cost effectiveness between the two policies. Of the total 80 projects, the next 12 projects generated co-benefits. They are 1) extend restriction area of solid fuel use, 2) expand subsidy of low-$NO_x$ burner, 3) supply hybrid-vehicles, 4) supply electric-vehicles, 5) supply hydrogen fuel cell vehicles, 6) engine retrofit, 7) scrappage of old car, 8) low emission zone, 9) transportation demand management, 10) supply land-based electric of ship, 11) switching anthracite to clean fuel in private sector, 12) expand regional combined-energy supply. The benefits of air pollutants and greenhouse gas-related measures were an annual average of KRW 2,705.4 billion. The social benefits of the transportation demand management were the highest at an annual average of KRW 890.7 billion, and followed by scrappage of old cars and expand regional combined-energy supply. When the social benefits and the annual investment budgets are compared, the cost effectiveness ratio is estimated to be about 3.8. Overall, the reduction of air pollutants caused by the air quality management policy of Gyeonggi-do resulted in an annual average of KRW 4,790.2 billion. In the point sources management sector, the added value of $CO_2$ reduction increased by 4.8% to KRW 1,062.8 billion, while the mobile sources management sector increased by 3.6% to KRW 3,414.1 billion. If social benefits from $CO_2$ reduction are added, the annual average will increase by 7.2% to KRW 5,135.4 billion. The urban and energy management sectors have shown that social benefits increase more than twice as much as the benefits of $CO_2$ reduction. This result implies that more intensive promotion of these measures are needed. This study has significance in that it presents the results of the empirical analysis of the co-benefits generated between the similar policies in the air quality management and the climate change policy which are currently being promoted in Gyeonggi-do. This study suggested that the method of analyzing the policy effect among the main policies in the climate atmospheric policy is established and the effectiveness and priority of the major policies can be evaluated through the policy correlation analysis based on the co-benefits. It is expected that it could be a basis for evaluation the efficiency of the climate change adaptation and air quality management policies implemented by the national and local governments in the future.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.183-184
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• 2013

Two main MBE growth techniques have been used: plasma-assisted MBE (PA-MBE), which utilizes a rf plasma to supply active nitrogen, and ammonia MBE, in which nitrogen is supplied by pyrolysis of NH3 on the sample surface during growth. PA-MBE is typically performed under metal-rich growth conditions, which results in the formation of gallium droplets on the sample surface and a narrow range of conditions for optimal growth. In contrast, high-quality GaN films can be grown by ammonia MBE under an excess nitrogen flux, which in principle should result in improved device uniformity due to the elimination of droplets and wider range of stable growth conditions. A drawback of ammonia MBE, on the other hand, is a serious memory effect of NH3 condensed on the cryo-panels and the vicinity of heaters, which ruins the control of critical growth stages, i.e. the native oxide desorption and the surface reconstruction, and the accurate control of V/III ratio, especially in the initial stage of seed layer growth. In this paper, we demonstrate that the reliable and reproducible growth of GaN on Si (110) substrates is successfully achieved by combining two MBE growth technologies using rf plasma and ammonia and setting a proper growth protocol. Samples were grown in a MBE system equipped with both a nitrogen rf plasma source (SVT) and an ammonia source. The ammonia gas purity was ＞99.9999% and further purified by using a getter filter. The custom-made injector designed to focus the ammonia flux onto the substrate was used for the gas delivery, while aluminum and gallium were provided via conventional effusion cells. The growth sequence to minimize the residual ammonia and subsequent memory effects is the following: (1) Native oxides are desorbed at $750^{\circ}C$ (Fig. (a) for [$1^-10$] and [001] azimuth) (2) 40 nm thick AlN is first grown using nitrogen rf plasma source at $900^{\circ}C$ nder the optimized condition to maintain the layer by layer growth of AlN buffer layer and slightly Al-rich condition. (Fig. (b)) (3) After switching to ammonia source, GaN growth is initiated with different V/III ratio and temperature conditions. A streaky RHEED pattern with an appearance of a weak ($2{\times}2$) reconstruction characteristic of Ga-polarity is observed all along the growth of subsequent GaN layer under optimized conditions. (Fig. (c)) The structural properties as well as dislocation densities as a function of growth conditions have been investigated using symmetrical and asymmetrical x-ray rocking curves. The electrical characteristics as a function of buffer and GaN layer growth conditions as well as the growth sequence will be also discussed. Figure: (a) RHEED pattern after oxide desorption (b) after 40 nm thick AlN growth using nitrogen rf plasma source and (c) after 600 nm thick GaN growth using ammonia source for (upper) [110] and (lower) [001] azimuth.

• 생명과학회지
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• 제33권8호
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• pp.639-650
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• 2023

가열담배(heated tobacco products, HTPs) 에어로졸 내 유해 성분들의 수준은 담배 연기와 비교해 현저히 낮은 것으로 보고되었지만, HTPs 사용이 담배 흡연과 연관된 심혈관 위험을 완화할 수 있는지는 불분명하다. 현재 연구는 습관성 흡연자들을 대상으로 담배 흡연에서 HTPs 사용으로의 단기간 전환이 심장 자율신경조절(cardiac autonomic regulation, CAR)에 미치는 영향을 탐색하기 위한 목적으로 수행되었다. 건강한 20대 남성 흡연자 7명은 5일 동안 담배 흡연(cigaette smoking, CS), 3가지 서로 다른 HTPs 사용(IQOS use, IQ; lil SOLID use, LS; lil HYBID use, LH) 혹은 흡연 중단(non-smoking, NS)으로 구성된 개방표지, 무작위 교차설계 시험을 완료했다. 각 세션은 1주의 세척 기간으로 분리되었으며, 세션당 할당된 제품 사용 전과 사용 후 24, 48, 72, 96 및 120시간에서 생체 이물[CO (carbon monoxide) and COHb (carboxyhemoglobin)], 혈류역학적 변인(systolic and diastolic blood pressure) 및 CAR 조절을 반영하는 HRV (heart rate variability) 지표들의 수준이 평가되었다. 호기 CO 및 COHb 수준은 NS에서만 통계적으로 유의하게 감소했다. 모든 세션 내 혈류역학적 변인에서 통계적 변화는 없었다. 그러나r HRV 스펙트럼 분석에서 lnHF (log-transformed high frequency, lnHF)는 NS를 포함한 IQ와 LS에서 유의하게 증가하였으며, HFnu (normalized HF)는 NS와 LH에서 통계적으로 증가하였다. lnHF와 HFnu는 각각 세션 간 시간에 따른 유의한 상호작용효과를 나타냈다. 현재 연구는 습관성 흡연자들에게서 HTPs 사용으로의 단기간 전환이 담배 흡연에 의한 심장 미주신경 긴장도 저하를 개선하여 CAR에 영향을 미칠 수 있음을 시사한다.

• 한국버섯학회지
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• 제2권3호
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• pp.115-126
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• 2004

원형질체 융합에 의한 화합성 및 불화합성 종간 체세포 잡종을 얻었다. 화합성 종간인 Pleurotus ostreatus와 P. florida의 융합체는 이질핵체(heterokaryon)를 형성하였고, 불화합성 종간인 P. cornucopiae + P. florida, P. ostreatus + Ganoderma applanatum, P. florida + Ganoderma lucidum, 그리고 P. ostreatus + Flammulina velutipes는 합핵체(synkaryon)를 형성하였다. 이질이핵체는 동일한 양상의 자실체를 형성하는데 비해 합핵체는 유사분열상의 꺽쇠연결체 형성, 한쪽 친과 유사한 자실체 형성, 비정상적 유전형질 분리 및 유전자재조합 현상을 나타내었다. 화합성 및 불화합성 계통간 융합체의 RAPD 분석결과 화합성 종간 융합체는 동일한 DNA 패턴을 나타내었고, 불화합성 종간 융합체는 한쪽 친과 유사한 DNA 양상이면서 비양친 DNA 밴드도 형성하였다. 합핵체의 패턴은 microgenome insertion type과 macrogenome insertion type으로 구분되었다. 합핵체의 자실체 발생은 융합 모균주 양친의 자가임성에 의존하는데 이는 느타리의 동형핵체 자가임성과 유사한 양상이었고, 교배형 전환과 관련이 있는 것으로 사료된다. 여기서는 이러한 관점에서 논할 것이다.