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Transition metal dichalcogenides (TMDs) are layered two-dimensional (2D) semiconductors and have received significant attention for their potential application in field effect transistors (FETs), owing to their inherent characteristics. Among the various reported 2D TMD materials, monolayer (ML) molybdenum disulfide (MoS2) is being considered as a promising channel material for the fabrication of future transistors with gate lengths as small as ∼1 nm. In this work, we present chemical vapor deposition-grown triangular ML MoS2 with a lateral size of ∼22 μm and surface coverage of ∼47%, as well as a PMMA-based wet transfer process for depositing the as-grown triangular ML MoS2 flakes onto a SiO2 (∼100 nm)/p++-Si substrate. Additionally, we demonstrate the fabrication of an n-type MoS2-based FET device and study its electrical characteristics as a function of the gate voltage. Our FET device shows an excellent on/off ratio of ∼106, an off-state leakage current of less than 10– 12 A, and a field effect mobility of ∼10.4 cm2/Vs at 300 K.

We experimentally investigate the cross-plane figure of merit (ZT) for an Al2O3/ZnO (AO/ZnO) superlattice film by measuring cross-plane electrical and thermal conductivity and Seebeck coefficient using the 3-ω method and an in-house Seebeck coefficient measurement system recently developed for 300–500 K and examine how ZT factors depend on the AO layer inside the AO/ZnO superlattice film using measured thermoelectric properties. The AO/ZnO superlattice film exhibited maximum power factor of ∼276.2 μW/m K2 with low thermal conductivity (∼0.31 W/m K), producing ZT ≥ 0.45 at 500 K, which is approximately 2,650% improvement compared with an undoped ZnO film (∼0.017). The enhanced ZT performance of the AO/ZnO superlattice film can be explained by enhanced phonon scattering at the interface and minority carrier blocking at the interfacial barrier due to the AO layer, suggesting that the interfacial AO layer is important to enhance ZT in oxide-based films. These results open new applications for micro- or nanosc...

We report on the electrical properties of natural p-type GeSe nanoflakes, which were mechanically exfoliated from GeSe single crystals by the polydimethylsiloxane (PDMS) stamp method, using a back-gate field effect transistor (FET) measured in a vacuum probe station at room temperature. In this study, we used two contact metals, including Au and Cr metals, as the Ohmic contacts to the GeSe nanoflake FETs, resulting in an Ohmic behavior with the Au contacts, with a total resistance of 5.5 × 106 Ω. We also found that the 40-nm-thick GeSe nanoflake FET exhibits clear p-type semiconductor behavior with a field-effect mobility of ∼1.0 × 10–3 cm2/(V · s) and a current on/off ratio of ∼104 at room temperature.

BACKGROUND The purpose of this study was to compare the outcome of carbapenem versus non-carbapenem antimicrobial therapy for pediatric urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae. MATERIALS AND METHODS From 2006 to 2011, 42 episodes of UTI caused by ESBL-producing Enterobacteriaceae were diagnosed at Seoul National University Children's Hospital. Patients were grouped according to the antimicrobials they received into a carbapenem group and a non-carbapenem group. Medical records were retrospectively reviewed to assess treatment outcome, time to defervescence after initiation of treatment, and relapse rate. RESULTS There were 36 children with 42 episodes of UTI caused by ESBL-producing Enterobacteriaceae. Twenty-seven cases (64%) had an underlying urologic disease, 28 (67%) cases were caused by Escherichia coli, and 14 (33%) cases were caused by Klebsiella pneumoniae. Four (10%) cases were treated with carbapenem, 23 cases (55%) were treated with non-carbapenem, and 15 (36%) cases were treated by switching from a carbapenem to a non-carbapenem and vice versa. There was no treatment failure at the time of antimicrobial discontinuation. Between the carbapenem and the non-carbapenem treatment groups, there were no significant differences in bacterial etiology (P = 0.59), time to defervescence after the initiation of antimicrobials (P = 0.28), and relapse rate (P = 0.50). In vitro susceptibility to non-carbapenem antimicrobials did not affect the time to defervescence after the initiation of antimicrobial treatment, and the relapse rate in the non-carbapenem group. CONCLUSIONS This study found no significant difference in the treatment outcome between pediatric patients treated with carbapenem and those treated with non-carbapenem antimicrobials for UTI caused by ESBL-producing Enterobacteriaceae. Therefore, the initially administered non-carbapenem can be maintained in UTI patients showing clinical improvement.

This study simulated the operation of a steam injected gas turbine combined heat and power (CHP) system. A full off-design analysis was carried out to examine the change in the turbine blade temperature caused by steam injection. The prediction of turbine blade temperature was performed for the operating modes suggested in the previous study where the limitation of compressor surge margin reduction was analyzed in the steam injected gas turbine. It was found that both the fully injected and partially injected operations suggested in the previous study would cause the blade temperature to exceed that of the pure CHP operation and the under-firing operation would provide too low blade temperature. An optimal operation was proposed where both the turbine inlet temperature and the injection amount were modulated to keep both the reference turbine blade temperature and the minimum compressor surge margin. The modulation was intended to maintain a stable compressor operation and turbine life. It was shown that the optimal operation would provide a larger power output than the under-firing operation and a higher efficiency than the original partially injected operation.

This study simulated the effect of steam injection on the performance and operation of a gas turbine combined heat and power (CHP) system. A commercial simple cycle gas turbine was analyzed. A full off-design analysis was carried out to investigate the variations in not only engine performance but also the operating characteristics of the compressor caused by steam injection. Variation in engine performance and operation characteristics according to various operation modes were examined. First, the impact of full steam injection was investigated. Then, operations aiming to guarantee a minimum compressor surge margin, such as under-firing and partial steam injection, were investigated. The former and latter were turned out to be relatively superior to each other in terms of power and efficiency, respectively. †† 1. 서 론 일반적으로 수백MW의 전력을 생산할 수 있는 대형 가스터빈에 비하여 수MW의 소형 가스터빈은 주로 자가발전을 포함한 분산 발전에 사용된다. 특히, 전력 공급이 원활하지 못한 지역이나 발전 요금이 고가인 피크부하 시간대에는 기존에 공급되는 전력 외에 소형 가스터빈으로 전력을 생산하여서 전력 수급을 용이하게 할 수도 있다. 또한 최근 가스터빈 열병합 발전을 이용한 Community Energy System(CES)이 각광을 받고 있는데, 역시 소형 가스터빈의 좋은 응용 분야이다

MW-class gas turbines are suitable for distributed generation systems such as community energy systems(CES). Recently, biogas is acknowledged as an alternative energy source, and its use in gas turbines is expected to increase. Steam injection is an effective way to improve performance of gas turbines. This study intended to examine the influence of injecting steam and using biogas as the fuel on the operation and performance a gas turbine combined heat and power (CHP) system. A commercial gas turbine of 6 MW class was used for this study. The primary concern of this study is a comparative analysis of system performance in a wide biogas composition range. In addition, the effect of steam temperature and injected steam rate on gas turbine and CHP performance was investigated.

RFID, a core technology that can be used to create a ubiquitous society, is a non-contact recognition system in which a small chip attached to various types of products transmits and processes information regarding the product and the surrounding environment via wireless communication. As a wireless recognition technology, RFID consumes little power, is small, and allows one to communicate in virtually any environment. It is thus expected to be very convenient. However, due to these characteristics of RFID systems, it may also pose a serious threat to privacy. A number of studies are currently being conducted to address this problem. Most of these studies use secure communication channels between a database and a reader, and insecure communication channels between a reader and a tag. However, this paper proposes a secure authentication protocol to provide information to an authorized entity by applying recognition technology in an insecure communication channel even for the communication between the database and the reader.

RFID system is core technology that construct ubiquitous environment for replacement of barcode technology. Use ratio of RFID system rapidly increase because the technology has many good points such as identification speed, storage space, convenience etc. But low-cost tag operates easily by query of reader, so the system happened user privacy violent problem by tag information exposure. The system studied many ways for security application, but operation capability of low-cost tag is about gates, but only gates allocated security part. So it is difficult to apply security to the system. Therefore, this scheme uses dividing 64 bits and reduces arithmetic, so proposed scheme provide mutual authentication that can apply to low-cost RFID system. Existing methods divide by 4 and used 96 bits. However, that reduces 32 bits length for lightweight and reduced from communication number of times of 7 times to 5 times. Also, because offer security by random number than existing scheme that generate two random numbers, that is more efficient. However, uses hash function for integrity that was not offered by XOR arithmetic and added extension of proposed scheme. Extended scheme is not offered efficiency than methods that use XOR arithmetic, but identification distance is mode that is proposed secure so that can use in for RFID system.

The RFID system, a core technology used in building a ubiquitous environment utilizing radio frequency identification, is an alternative to bar-codes. The RFID system has become very popular, with various strengths such as recognition speed and non-touch method. However, there are some problems remaining as the low- cost tag can be operated through query, which leads to information exposure and privacy encroachment. Various approaches have been used to increase security of the system, but the low-cost tag, which has about 5 K-10 K gate capabilities, can only allocate 250-3 K gate to security. Therefore, the current study will provide a reciprocal authentication solution that can be used with low-cost RFID systems, by separating 64 bit keys and minimizing calculations. Existing systems divided a 96 bit key into 4 parts. However, the proposed system reduces the key to 32 bits, and reduces the communications down to 5 from 7. Also, one additional random number is added to the existing two numbers to increase security. To improve the previous system, which only provided XOR calculations, an additional hash function was added. The added procedure does not increase effectiveness, compared to the XOR calculation, but does provide more security to the RFID system, which can be used in remote distances.

With the development in IT technology and with the growing demands of users, a ubiquitous environment is being made. Ubiquitous stands for a convenient environment in which users can get information and services through networks with devices that can communicate. This ubiquitous environment requires device technology, and Radio Frequency IDentification(RFID) is a good example. RFID, a technology that identifies radio frequency, was developed to substitute bar-codes and has various strengths, such as high recognition rates, quick recognition speed, and large storage. Because of these strengths, it is being used in various fields such as the public, distribution, and financial sectors; but it has a weakness in privacy, as readers operating within the same frequency bandwidth can be easily tagged. By acquiring information from the tag, unauthorized people can assess into the personal information of users. The current study, therefore, provides a secure and effective protection method, which can guarantee anonymity towards users with tags.

It has been estimated that 'RFID' technology would be playing an important role in the incoming ubiquitous environment. But, the communication between tag and reader in RFID system has been conducted by wireless communication of radio frequency so that the information on identification could be eavesdropped by the third party maliciously. Such eavesdropped information could be also used as basic information in attaching others; in this regard, it could impair the privacy of its users and the users have avoided using 'RFID.' Therefore, many studies have been performed and the output of Tag has been varied by means of updating the ID in order to solve such a problem. Though, the ID synchronization between database and tag should be done in the ID update process. Therefore, in this paper, we propose a RFID authentication protocol which offers synchronization.

The RFID system is a core technology used in building a ubiquitous environment, and is considered an alternative to bar-code identification. The RFID system has become very popular, with various strengths such as fast recognition speed and non-touch detection. However, there are some problems remaining, as the low-cost tag can operate through queries, leading to information exposure and privacy encroachment. Various approaches have been used to increase the security of the system, but the low-cost tag, which has about 5K-10K gates, can only allocate 250-3K gates to security. Therefore, the current study provides a reciprocal authentication solution that can be used with low-cost RFID systems, by splitting 64 bit keys and minimizing calculations. Existing systems divided a 96 bit key into 4 parts. However, the proposed system reduces the key to 32 bits, and reduces communications from 7 down to. 5. To increase security, one additional random number is added to the two existing numbers. The previous system only provided XOR calculations, however in the proposed system an additional hash function was added. The added procedure does not increase effectiveness in terms of the XOR calculation, but provides more security to the RFID system, for better use over remote distances.

RFID, a core technology that can be used to create a ubiquitous society, is a non-contact recognition system in which a small chip attached to various types of a product transmits and processes information regarding the product and the surrounding environment via wireless frequency. As a wireless recognition technology, RFID consumes little power, is small, and allows one to communicate in virtually any environment. It is thus expected to offer much convenience. Due to these characteristics of the RFID system, however, it may also pose a serious threat to privacy. A number of studies are currently being conducted to address this problem. Most of these studies use secure communication channels between a database and a reader, and insecure communication channels between a reader and a tag. This paper, however, proposes a secure authentication protocol to provide information to an authorized entity by applying the recognition technology in the insecure communication channel even for the communication between the database and the reader.

Recently, much research has been actively conducted for a new kind of network environment ubiquitous computing. This paper will define the essential technology called ad hoc network and the smart-Tag technology required by a ubiquitous environment. This paper proposes a PRF and a public key scheme based on a secure hash function. The proposed scheme is a secure authentication protocol for complementing the weak security points of the conventional scheme. In particular, the scheme using the PRF makes it possible to renew MITMA and ID using random numbers while the scheme using the public key can perform a secure authentication scheme using a pair of keys which are shared in the reader in advance.

목적: 본 연구는 소아 환자들에서 voriconazole 치료적 약물 농도 모니터링의 임상적 의의를 분석하고자 하였다. 방법: 2010년 7월부터 2012년 6월까지 서울대학교병원에 입원한 18세 이하의 소아 환자들 중, 침습성 진균감염증에 대해 voriconazole 치료를 받은 증례를 후향적 의무기록 분석을 통해 분석하였다. 본 연구에 포함된 총 28명의 환자 중 14명이 약물 농도 모니터링을 받았으며, 143개의 혈중 농도 측정 값을 분석하였다. 모든 환자들에게서 치료 효과 및 독성 증상 발현 여부를 파악하였다. 결과: 143개의 혈중 농도 측정 값 중 53.1%에서 치료적 범위(1.0-5.5 mg/L) 내에 들었고, 같은 용법으로 치료받았더라도 높은 혈중 농도 변동성(high variability)을 보였다. 약물 농도 모니터링을 받았던 군(TDM 군)과 받지 않았던 군(non-TDM 군)에서 각각 14명 중 9명(64.3%)이 독성 증상을 나타냈는데, TDM 군에서 신경학적 증상(n=2, 14.3%) 및 간기능 장애(n=8, 57.1%)는 높은 voriconazole 혈중 농도(>5.5 mg/L)를 보인 환자들에게서 나타났다. 반면, 시각 장애는 혈중 농도가 치료적 범위 내에 있을 때 발현하였다(1.18 mg/L, 3.9 mg/L). TDM 군에서 non-TDM 군에 비하여 독성 증상으로 인하여 약물을 중단했던 빈도가 낮았다(0.0% vs. 18.2%, P =0.481). 치료 시작 6주 후 치료 효과를 분석해본 결과 TDM 군의 57.2%에서 치료에 대한 반응을 보였으나, non-TDM 군에서는 14.3%에서 치료 반응을 보였다(P =0.055). 최종 치료효과 분석에서는 TDM 군의 21.4%에서 치료 반응을 보였으나, non-TDM 군의 14.3%에서 치료 반응을 보였다(P =0.664). TDM 군에서 치료 시작 첫 6주 동안 혈중 약물 농도를 분석했을 때 67.0% 이상에서 치료적 범위 내에 들었으나, 치료 기간 전체를 봤을 때에는 45.5%에서 치료적 범위 내에 들었다. 결론: 소아에서 voriconazole 사용 시 치료적 약물 농도 모니터링을 통하여 치료 목표를 효과적으로 달성하고, 독성이 나타나는 것을 예방할 수 있다. 【Purpose: To determine the clinical significance of voriconazole therapeutic drug monitoring (TDM) in the pediatric population. Methods: Twenty-eight patients with invasive fungal infections administered with voriconazole from July 2010 to June 2012 were investigated retrospectively. Fourteen received TDM, and 143 trough concentrations were analyzed. All 28 patients were assessed for adverse events and treatment response six weeks into treatment, and at the end. Results: Out of 143 samples, 53.1% were within therapeutic range (1.0-5.5 mg/L). Patients administered with the same loading (6 mg/kg/dose) and maintenance (4 mg/kg/dose) dosages prior to initial TDM showed highly variable drug levels. Adverse events occurred in 9 of 14 patients (64.3%) in both the TDM and non-TDM group. In the TDM group, voriconazole-related encephalopathy (n=2, 14.3%) and aspartate aminotransferase (AST) or alanine aminotransferase (ALT) elevation (n=8, 57.1 %) occurred with serum levels in the toxic range (>5.5 mg/L), whereas blurred-vision (n=2, 14.3%) occurred within the therapeutic range (1.18 mg/L and 3.9 mg/L). The frequency of voriconazole discontinuation due to adverse events was lower in the TDM group (0.0% vs. 18.2%, P =0.481). Overall, 57.2% of the patients in the TDM group versus 14.3% in the non-TDM group showed clinical response after 6 weeks (P =0.055), whereas 21.4% in the TDM group versus 14.3% in the non-TDM group showed response at final outcome (P =0.664). In the TDM group, >67.0% of the serum levels were within therapeutic range for the first 6 weeks; however 45.5% were within therapeutic range for the entire duration. Conclusion: Routine TDM is recommended for optimizing the therapeutic effects of voriconazole.】

Results: The peak incidence of hMPV infection was observed in May, whereas for RSV infections in November and Decem- ber. hMPV infection occurred in older patients compared to RSV A and B infection (29.9±32.5 months vs. 13.6±15.4 months, P