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The synthesis of fluorine-18 labeled fluoroform with high molar activity has grown in importance for the development of fluorine-18 labeled aryl-CF3 radiopharmaceuticals that are useful as diagnostic radiotracers for the powerful technique of positron emission tomography (PET). We designed a strategy of synthesizing fluorine-18 labeled fluoroform from N1-difluoromethyl-N3-methyltriazolium triflate (1) via SN2 fluorination without stable fluorine isotope scrambling. Fluoroform was generated at rt in 10 min by fluorination of the triazolium precursor with TBAF (6 equiv.). We propose three routes (a), (b), and (c) for this fluorination. Quantum chemical calculations have been carried out to elucidate the mechanism of experimentally observed nucleophilic attack of fluoride at difluoromethyl group via route (a), not N3-methyl via route (b). 1H and 19F NMR studies using deuterium source have been performed to examine the competition between SN2 fluorination (route (a)) and the formation of difluorocarbene (route (c)). The observed superiority of SN2 pathway to formation of difluorocarbene in the reaction of the precursor using CsF in (CD3CN/(CD3)3COD (17.8 : 1)) gives the possibility of preparing the fluorine-18 labeled fluoroform in high molar activity.

We review crown ether-facilitated nucleophilic reactions using metal salts, presenting the studies using kinetic measurements and quantum chemical methods. We focus on the mechanistic features, specifically on the contact ion-pair (CIP) mechanism of metal salts for nucleophilic processes promoted by crown ethers and derivatives. Experimental verification of the CIP form of the metal salt CsF complexed with [18-Crown-6] by H-NMR spectroscopy is described. The use of chiral crown ethers and derivatives for enantioselective nucleophilic processes is also discussed.

We present a quantum chemical analysis of the

Quantum chemical analysis is presented, motivated by Grée and co-workers’ observation of salt effects [Adv. Synth. Catal. 2006, 348, 1149–1153] for SN2 fluorination of KF in ionic liquids (ILs). We examine the relative promoting capacity of KF in [bmim]PF6 vs. [bmim]Cl by comparing the activation barriers of the reaction in the two ILs. We also elucidate the origin of the experimentally observed additional rate acceleration in IL [bmim]PF6 achieved by adding KPF6. We find that the anion PF6− in the added salt acts as an extra Lewis base binding to the counter-cation K+ to alleviate the strong Coulomb attractive force on the nucleophile F−, decreasing the Gibbs free energy of activation as compared with that in its absence, which is in good agreement with experimental observations of rate enhancement. We also predict that using 2 eq. KF together with an eq. KPF6 would further activate SN2 fluorination

We present the intra- and inter-molecular organocatalysis of SN2 fluorination using CsF by crown ether to estimate the efficacy of the promoter and to elucidate the reaction mechanism. The yields of intramolecular SN2 fluorination of the veratrole substrates are measured to be very small (&lt, 1% in 12 h) in the absence of crown ether promoters, whereas the SN2 fluorination of the substrate possessing a crown ether unit proceeds to near completion (~99%) in 12 h. We also studied the efficacy of intermolecular rate acceleration by an independent promoter 18-crown-6 for comparison. We find that the fluorinating yield of a veratrole substrate (leaving group = −OMs) in the presence of 18-crown-6 follows the almost identical kinetic course as that of intramolecular SN2 fluorination, indicating the mechanistic similarity of intra- and inter-molecular organocatalysis of the crown ether for SN2 fluorination. The calculated relative Gibbs free energies of activation for these reactions, in which the crown ether units act as Lewis base promoters for SN2 fluorination, are in excellent agreement with the experimentally measured yields of fluorination. The role of the metal salt CsF is briefly discussed in terms of whether it reacts as a contact ion pair or as a “free” nucleophile F−.

The synthesis of fluorine-18 labeled fluoroform with high molar activity has grown in importance for the development of fluorine-18 labeled aryl-CF

This paper proposes a novel channel estimation technique for the offset quadrature amplitude modulation based filter bank multi-carrier (FBMC/OQAM) systems. Unlike the conventional approaches, the proposed pilot signals utilize their intrinsic interference for the channel estimation, and provide an improved power efficiency compared to the conventional auxiliary pilot method. However, due to the non-whiteness of the noise components at the output of the analysis filter banks, the power gain obtained by the proposed scheme cannot be maximized. To overcome this difficulty, we propose a semiblind channel estimation by grouping the pilot signals and imposing sign ambiguities to them. Theoretical analysis shows that the proposed semiblind channel estimation remarkably improves the power efficiency of its non-semiblind version. Finally, it is demonstrated that the near optimum detection performance is achieved by the proposed scheme at a reduced complexity.

An ATSC 3.0 physical layer frame consists of a bootstrap immediately followed by a preamble containing layer 1 control signaling and then one or more subframes carrying payload data. Subframes within a particular frame may be of the same or different types, with different subframe types being configured for different classes of receivers (e.g., mobile versus fixed). This paper focuses on the subframe structure, configuration, and contents, including subframe boundary symbols which carry additional pilots to assist with channel estimation at the receiver and cell multiplexing which maps physical layer pipe (PLP) payload data to physical layer resources within each subframe. Various methods for cell multiplexing multiple PLPs within a subframe are discussed and described, including time division multiplexing, frequency division multiplexing, time-frequency division multiplexing, and layered division multiplexing. Frequency interleaving, pilot insertion, and guard interval insertion are also covered, including a method of distributing extra samples to guard intervals in order to obtain frame lengths equal to an integer number of milliseconds.

The digital video broadcasting—second generation terrestrial (DVB-T2) standard has adopted a preamble called P1 symbol to achieve the fast time and frequency synchronization. The P1 symbol also carries basic transmission parameters of DVB-T2 system, such as fast Fourier transform size, guard interval size and transmission type—single input single output or multiple input single output, etc. In this paper, we propose an improved preamble which is modulated by a novel hybrid differential modulation scheme that can provide transmit diversity gain to achieve the same performance of coherent transmission. The proposed preamble has demonstrated a significantly improved signaling error rate performance over various channel conditions compared to the conventional P1 symbol in DVB-T2.

The recent wearable device’s applications concentrates on providing diverse services such as location based service, context aware service to the users. These various services are implemented by the interactions between the wearable device and the user. In the legacy system, the interaction requires certain explicit configuration from the user. If the user is unfamiliar with the IT technology, it will be impossible to get the wanted service. Therefore, a new autonomous communication concept among neighbor devices is essential for people who is unfamiliar with the IT technology. The implicit human computer interface enables the user to acquire the services, even though the user don’t know the IT technology. In this paper, we propose two BLE based protocols (B-LIDx protocol, B-PniP). B-LIDx protocol is the protocol for locationing the mobile device in indoor. B-PniP is a zero-configure opportunistic direct M2M communication protocol between neighbor devices to achieve the autonomous communication concept with zero-configuration. The protocol’s evaluations are performed by measuring the time for finding the location of a mobile device in actual environment and aligning the time spent in services using the B-PniP. 논문 14-39C-02-05 한국통신학회논문지(J-KICS) '14-02 Vol.39C No.02 http://dx.doi.org/10.7840/kics.2014.39C.2.151 151 ※본 연구는 미래창조과학부 및 한국산업기술평가관리원의 산업융합원천기술개발사업(SW.컴퓨팅)의 일환으로 수행되었습니다. [10041145, 자율군집을 지원하는 웰빙형 정보기기 내장 소프트웨어 플랫폼 개발] First Author : 경북대학교 전자공학부 실시간시스템 연구실, ohyoungho88@naver.com, 학생회원 ° Corresponding Author : 경북대학교 전자공학부 실시간시스템 연구실, sjkang@ee.knu.ac.kr, 종신회원 * 경북대학교 전자공학부 실시간시스템 연구실, faithlee3@hanmail.net 논문번호:KICS2013-11-495, 접수일자:2013년 11월 15일, 심사일자:2014년 1월 14일, 최종논문접수일자:2014년 1월 27일 한국통신학회논문지(J-KICS) '14-02 Vol.39C No.02

We analyze the effects of protecting group(s) on the efficiency of aromatic 18F-labeling of guanidine-containing radiopharmaceuticals by quantum chemical methods. We elucidate the origin of experimental observations: The fully protected N,N’,N’’,N’’-tetrakis-Boc guanidine group exhibits remarkably enhanced reactivity and improved selectivity in contrast to both N,N’-bis-Boc protected guanidine and its isomer in the absence of hydrogen bonding with fluoride ion. We find that this very intriguing observation of reaction rates highly depending on the position of protection by –Boc is due to the effects of strong Coulombic interactions among the ionic species, which allow an optimal position (just above the electropositive carbon and the leaving group) of F− in the reaction involving the fully protected N,N’,N’’,N’’-tetrakis-Boc guanidine group.

In this work, we develop a new pilot-aided channel estimation for filter bank multi-carrier (FBMC) systems. The proposed method is different from previous approaches in the sense that it uses the intrinsic interference rather than cancelling it. By doing so, we can obtain a virtual power boosting effect without increasing power budget. The estimation, detection, and peak-to-average power ratio (PAPR) performance of the proposed scheme are demonstrated through the computer simulation.

The adoption of a composite beam system is regarded as a simple but effective solution because it improves the overall stiffness, strength and stability of the structure by welding shear studs. However, welding shear studs poses problems including electric shock and weld defects. Mechanical methods have emerged as an alternative to metallurgical methods for connecting the H-beam and shear connector. Four specimens were tested in order to compare the structural behavior of the proposed composite beams with that of the classical composite beam given the condition of horizontal loading. With the original composite beam (FCB-SB specimen) using stud bolts, hysteresis loops are stable, but its strength decreased with the crashing of the concrete slab around the column. The suggested composite beams using shear connectors also yielded stable hysteresis loops. Consequently, use of the suggested composite beams instead of the original composite beam are recommended.

본 논문의 연구 목표는 대학의 기술마케팅 성공에 영향을 미치는 요인에 대하여 실증 분석하였다. 이를 위해서 2006년부터 2008년까지 기술이전 실적이 있는 207개 대학의 실적을 9개 가설로 검증하였다. 가설검증을 위해 과학기술 인프라(연구비, SCIE 게재 논문 수), 특허관련 보상제도(출원, 등록), 특허 건수(출원, 등록), TLO 직원(기술이전 계약담당자 수, 산업체근무경력), 기술 이전 보상제도(연구자, 기여자) 및 인식(대학 경영층, 산업체)이 기술이전 성과인 기술료 수입금액 창출에 영향을 미치는 지에 대하여 구조 방정식 모형을 이용하여 분석하였으며 본 연구의 분석 결과를 요약하면 다음과 같다. 첫째, 대학의 과학기술 분야 연구비가 많을 수로 연구 역량이 높으며 특허 건수 확보에 정(+)의 영향을 미치는 것으로 나타났다. 둘째, 대학에서 시행하는 출원 및 등록 특허에 대한 연구자들의 보상제도는 연구자들의 연구 성과물을 특허로 출원하는데 동기를 부여하고 있는 것으로 판단된다. 셋째, 대학의 특허 보유건수가 증가하면 기술이전 대상이 많아지므로 기술이전 성과에 정(+)의 영향을 미치며 기술이전 전문 인력(기술거래사, 기업기술가치평가사, 변리사 등) 수도 늘어나야 하는 것으로 나타났다. 넷째, 대학 보유 특허 수의 증가로 기술이전이 확대되면 기술료 수익의 증가에 따라 연구자와 기여자의 보상이 늘어나게 된다. 본 연구에서는 대학에서 기술이전 성과에 영향을 주는 요인을 구조방정식 모형으로 분석하여 실증적으로 검증을 하였다는데 의의를 가질 수 있으며, 특히 현재 기술이전 활동을 활발히 하고 있는 대학들에게 밀접한 영향을 미치고 있는 요인에 대하여 정부의 산학협력 실태조사에 제출된 공식적인 자료에 대한 분석이 체계적으로 이루어졌다는 것이 선행연구들과의 차별성이라 할 수 있을 것이다. 【This research aims to empirically analyze the factors that affect the success of technology marketing by Korean universities. The total of 207 universities which successfully made technology transfers from 2006 to 2008 was examined to test the nine hypotheses. For the purpose of testing the hypotheses, technology infrastructure (research costs and the number of SCIE papers), the compensation system for the patents (application and registration), the number of patents (application and registration), TLO staff (the number of people in charge of technology transfer and the job experience in industries), the compensation system for technology transfers (researchers and contributors), and attitudes of university management and industries were analyzed with structural equation methods to figure out their effects on the revenues of technology transfer. The results of this research are summarized as follows. First, technology infrastructures of universities were found to have positive effects on securing patents. As the university research costs in the field of science and technology are increases, the research capabilities are enhanced and this a larger number of researchers are conducted. Second, this research shows that compensation systems for patent application and registration in universities have motivated researchers to take out patents for the outputs of their research. Third, the number of patents universities possess was found to have a positive effect on technology transfer. An increase in the number of patents universities possess implies an increase in the diversity and excellence of the target technologies for transfer. Fourth, the number of patents universities possess turned out to have a positive effect on TLO staff. The number of experts in charge of technology transfer including technology dealers, valuation analysis and patent attorneys should be increased as target technologies for transfer increase according to the increase of patents possessed. Because the technologies are transferee from universities to businesses, businesses (job) experience of TLO staff in industries are also important. This research is meaningful because it has identified the factors affecting the results of technology transfer by employing structural equation methods. In particular, an official governmental survey data for the academic-industrial cooperation were analyzed systematically in terms of technology infrastructure, compensation systems related to patents, the number of patents, TLO staff, compensation systems for technology transfer, and attitudes of university management and industries. All these facts might could differentiate this study from the previous studies.】

We present calculations for S N 2/E2 reactions in protic solvents (t-butyl alcohol, ethylene glycol). We focus on the role of the hydroxyl (-OH) groups in determining the S N 2/E2 rate constants. We predict that the ion pair E2 mechanism is more favorable than the naked ion E2 reaction in ethylene glycol. E2 barriers are calculated to be much larger (∼ 9 kcal/mol) than S N 2 reaction barriers in protic solvents, in agreement with the experimental observation [Kim, D. W. et al. J. Am. Chem. Soc. 2006, 128, 16394] of no E2 products in the reaction of CsF in t-butyl alcohol.

We present calculations for the mechanism of S(N)2 reactions in ethylene glycol, focusing on the role of two protic functional groups (-OH) in the solvent molecule. We find that some hydroxyl groups act as Lewis base to interact with the cation, whereas others affect the reaction as Lewis acid to the nucleophile. We predict that the nucleophile (F-) reacts as an ion pair rather than as a solvent-separated ion when metal cation (Cs+) is used as a counterion. The overall influence of ethylene glycol manifests itself as the reaction barrier (E(double dagger) = 20.0, G(353K)(double dagger) = 21.5 kcal/mol) that is a bit smaller than that in tert-butyl alcohol, which proved to be a very efficient solvent for S(N)2 reactions [Kim, D. W., et al. J. Am. Chem. Soc. 2006, 128, 16394]. We therefore show that a small protic solvent such as ethylene glycol may be as efficient as a bulky alcohol for S(N)2 reactions.

We calculate and compare the effects of aprotic vs protic solvent on the rate of SN2 reaction [F- + C3H7OMs--> C3H7F + OMs-]. We find that aprotic solvent acetonitrile is more efficient than a small protic solvent such as methanol. Bulky protic solvent (tert-butyl alcohol) is predicted to be quite efficient, giving the rate constant that is similar to that in CH3CN. Our calculated relative activation barriers of the SN2 reaction in methanol, tert-butyl alcohol, and CH3CN are in good agreement with experimental observations.

The decoding structure of up-to-date ATSC DTV receivers is well optimized, and it seems that 14.6 dB is the unbreakable minimum SNR in the AWGN channel. But the SNR satisfying the Shannon capacity of DTV receivers is 11.76 dB, So, the SNR gab between the 14.6 dB and the 11.76 dB is about 2.8 dB. In order to approach the Shannon capacity we propose a recursive trellis decoder which uses reliable feedback data obtained by an RS decoder. The performance enhancement of about 0.8 dB can be achieved in case of the AWGN channel.

In order to use limited frequency resources efficiently, a single frequency network using digital on-channel repeater(DOCR) has been studied and would be implemented. The DOCR generates strong pre-ghosts to ATSC DTV receivers. The forward filter of equalizer in ATSC DTV receivers compensates the distortion made by pre-ghosts. This process induces noise enhancement and colored noise, thereby results in the performance degradation. In this paper we propose to use a dual-feedback equalizer to combat strong pre-ghosts. The proposed equalizer has two feedback filters. One is the decision feedback filter and the other is non-decision feedback filter. The additional non-decision feedback filter decreases the noise by whitening the noise and preventing the generation of colored noise in pre-ghost channel. Thus the equalization technique of dual-feedback structure has performance enhancement in pre-ghost channel in comparison with conventional decision feedback equalizer(DFE). By simulation we analyzed the performance enhancements of DTV receiver using dual-feedback equalization structure.

In this paper, we propose an improved preamble scheme utilizing a novel hybrid differential modulation, which can provide both the spatial multiplexing and the transmit diversity gain. The proposed preamble scheme has demonstrated a significantly improved signaling error rate (SER) performance in various channel conditions as compared to the conventional P1 symbol scheme in DVB-T2 standard. Specifically, as much as 4dB SNR gains are observed in static TU-6 and DVB-NGH outdoor channels with and without 20 Hz Doppler shift presented, respectively.

In this paper we propose a hybrid Zadoff-Chu (ZC) based pilot sequence suitable for OFDM broadcast systems. While maintaining the same scattered pilot structure and the same power level as in DVB-T2, we replace the phase values by a ZC combined sequence. This combined sequence can either carry information bits through a repetition of small ZC patterns, or serve just as a very robust fine time domain synchronization mechanism. We present the design methodology for different OFDM systems, the possible ZC patterns sequences valid for signaling and provide a recommended structure for DVB-T2 like systems. Simulation results show that, without degrading the pilot channel estimation, an additional time domain synchronization more robust than P1 of DVB-T2 is achieved in each OFDM symbol. The proposed structure can be used as a design basis for future broadcast systems to build on, where a separate preamble will no longer be needed, thus, reducing the frame overhead.

The majority of acromioclavicular ioint injuries resuit from direct trauma to the shoulder. The magnitude of applied force determines the degree of injury. This article presents a modified Weaver-Dunn procedure consisting of lateral clavicle resection and reduction, coracoclavicular fixation with suture or surgical tape, and coracoacromial ligament transfer for the treatment of these injuries.

This paper presents symbol timing-offset compensation techniques to improve the reception performance of ATSC DTV receivers. Short and long echoes could induce timing-offset in the symbol timing recovery circuit. The timing-offset shifts sampling instant and causes the performance degradation of the equalizer. When many echoes exist, the optimal sampling instant is the point at which the main-path has a peak value. With a simple correlation technique, we find the optimal sampling instant and compensate the timing-offset with poly-phase filter. Simulation results show that the proposed timing-offset compensation techniques could give considerable enhancements in terms of symbol error rates.