• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.110-124
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• 1993

A Nonlinear model-based Hybrid Controller (NHC) is developed which consists of the adaptive proportional-integral-feedforward (PIF) gains and variable structure controller. The controller has the robustness against modeling uncertainty and is applied to the trajectory tracking control of single-input, single-output nonlinear systems. The essence of the scheme is to divide the control into four different terms. Namely, the adaptive P-I-F gains and variable structure controller are used to accomplish the specific control actions by each terms. The robustness of the controller is guaranteed by the feedback of estimated uncertainty and the performance specification given by the adaptation of PIF gains using the second method of Lyapunov. The variable structure controller is incorporated to regulate the initial peak of the tracking error during the parameter adaptation is not settled yet. The newly developed NHC method is applied to the power tracking control of a nuclear reactor and the simulation results show great improvement in tracking performance compared with the conventional model-based control methods.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.628-634
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• 1999

The orientational binding of ${\omega}$-phenylakylammonium ions to the sodium dodecyl (SDS) micellar interface has been studied from $^{1}H\;NMR$ chemical shift data. The NMR resonaces of the methylene protons of SDS and aromatic protons embedded into the micellar interior have shown the upfield shift. The aromatic induced chemical shifts of the alkyl chain methylene protons of SDS demonstrate the deep penetration into the palisade layer by these organic salts. Alkylammonium groups have been considered to be oriented toward outside of the micellar interface. Aromatic rings have been thought to be oriented toward the micellar core. The depth of penetration by organic salts has been observed to increase with the length of alkyl chain.

• Satellite Communications and Space Industry
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• v.4 no.1
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• pp.81-85
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• 1996

통신기술과 뉴미디어의 발굴로 개인 생활이 편리해지고 지구 전체가 동일 정보영역으로 묶여 하나의 생활권을 형성하는 지구촌 시대가 열리고 있다. 국내에서도 제 1세대 무궁화위성 1.2호의 발사를 계기로 위성시대가 개막되었으며, 인공위성 개발 열기가 한층 고조되고 있다. 그러나 현재 세계적으로 사용하고 있는 위성궤도는 대부분 정지궤도이며, 정지궤도는 한정된 궤도 영역과 위성의 수요증가 때문에 이미 포화상태에 이르러 향후 개발의 한계에 이르게 되었다. 그리고 90년대 초반부터 미국을 중심으로 세계적 규모의 저궤도 위성통신이 제안되기 시작하여 현재 다수의 시스템이 개발되고 있다. 저궤도 위성산업은 이동통신의 세계화와 대중화 추세에 따라 특히 경량 통신위성 시스템을 중심으로 구 수요가 급증할 것으로 예상되고 있으며 이를 통해 통신서비스를 제공하는 국제적 저궤도 위성사업도 활발히 추진되고 있어 앞으로 상업성이 매우 높은 중점 육성대상분야로 평가되고 있다. 현대전자에서 저궤도 위성사업 글로벌스타에 사용될 인공위성을 2005년까지 26기를 제작하여 쏘아 올리겠다고 선언하면서부터 국내의 우주개발 경쟁은 한층 가열되고 있다. 현대전자 산업전자연구소장이자 위성사업단장이신 이명기 전무님으로부터 야심찬 위성사업의 마스터 플랜과 추진현황, 전망 등에 대하여 들어보았다. 사업의 전망을 힘주어 역설하시는 모습이 위성사업에 대한 열정과 도적적 각오를 엿볼 수 있었으며 성공사업으로의 확신을 읽게 하였다.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.36-40
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• 2001

A series of new 2-N-benzyl-5-phenoxy-3-isothiazolone derivatives were synthesized and their in vitro antifungal activities against resistant Phytophthora capsici (RPC) & sensitive Phytophthora capsici (SPC) with metalaxyl fungicide have been measured. In addition, influence of substituted 5-phenoxy group on the -antifungal activities ($pI_{50}$) and the reactivity of substrates were investigated. From the results, reactivity of none substituted substrate showed tendency displaying orbital-controlled reaction. The substituents on the 5-phenoxy ring showed selective fungicidal activity between SPC and RPC. Especially, the 4-fluoro substituent, 6 in the RPC and 4-nitro substituent, 3 in SPC exhibited strongly selective antifungal activity among them. The activities on the SPC would depend largely on the optimal molar refractivity ($MR_{(opt.)}=7.37cm^3/mol$) whereas the activities on the RPC would depend largely on the optimal highest occupied molecular orbital energy ($HOMO_{(opt.)}=-9.2137e.v.$) and weak electron donating (${\sigma}<0$) group. And Free-Wilson analyses revealed that the antifungal activity against RPC depends on the methoxy and bromo-substituent and all of the substituents contribute to antifungal activities against SPC.

• Clean Technology
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• v.20 no.4
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• pp.359-366
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• 2014

Attrition characteristics of PKM1-SU particles, $CO_2$ absorbents for pre-combustion $CO_2$ capture process, and FCC particles, catalytic particles for hydro cracking of crude oil, were investigated at high temperature and high pressure conditions. Particle attrition tests were executed at various kinds of temperature ($0-400^{\circ}C$) and pressure (0-20 bar) conditions in a cylinder type bubbling fluidized bed with 15.1 cm diameter, 120 cm height and 1 mm orifice-sparger tube. Attrited particles before and after tests were analyzed by BET, optical microscopy, and particle size analyzer. Effects of bed material height (solid inventory) and steam injection were also verified by using ASTM D5757-95, conventional attrition test method.

• Convergence Security Journal
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• v.24 no.3
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• pp.219-229
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• 2024

The application of 4th Industrial Revolution technologies in the defense sector is accelerating, leading to the rapid incorporation of information and communication technologies (ICT) into military systems. The biggest threat to these ICT-based military systems is an electromagnetic pulse (EMP) attack, which can result from nuclear explosions or EMP bombs. North Korea's ongoing nuclear advancements and EMP bomb capabilities pose a critical threat, necessitating South Korea's preparedness for such attacks to ensure the effective operation of its ICT-based military systems. Despite this urgency, the South Korean military currently lacks comprehensive standards for EMP protection, relying only on the design criteria for EMP protection facilities for buildings. This gap highlights the absence of sufficient legal and regulatory measures and the lack of focused research to develop EMP protection performance standards for safeguarding military systems. Therefore, this paper aims to analyze existing EMP protection performance standards and relevant laws and regulations. It proposes improvements and establishes necessary standards to enhance the EMP resilience of military facilities and equipment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.6
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• pp.519-525
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• 1994

This experiment was conducted to investigate the effects of sowing date and cutting time on feed value of rye in paddy field at Yesan from Oct. 1990 to June 1991. The field experiment was sown 5 times at 10 day intervals from Oct. 5. The content of crude protein, digestible protein, total digestible nutrient(TDN), minerals(P, K, Ca, Mg), and energy(ENE, NEL, NEM, NEG) were decreased due to earlier sowing, while the content of acid detergent fiber (ADF) and neutral detergent fiber(NDF) increased. On the other hand, the yields per unit area for crude and digestible protein, TDN, minerals, and energy increased due to earlier sowing, but there was no significant difference among the plots sown on Oct. 5 through Oct. 25. The highest yield of crude protein was shown at late flowering stage, digestible protein and net energy gain (NEG) at heading stage and TDN at milk stage respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.1-8
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• 2005

An experimental investigation of a microthruster that uses hydrogen peroxide as a monopropellant is described. The study comprises of preparation method of silver as a catalyst and performance evaluation of a mesoscale reactor. Reduction of silver in $H_2\;at\;500^{\circ}C$ resulted in the best reactivity of all the treatment method tested. A mesoscale reactor was built to find the optimum configuration for full decomposition of propellant. The catalyst bed was made of a glass wafer substrate sputtered with silver and had a length of 20 mm. We measured the conversion rate with varying feed rate of $H_2O_2$ and preheating temperature. With the feed rate of $H_2O_2$, the space time within the reactor varies as well. For the bed length of 20 mm, space time more than 480 s was required for full conversion.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.383-393
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• 2000

In shared memory multiprocessor systems, false sharing occurs when several independent data objects, not shared but accessed by different processors, are allocated to the same coherency unit of memory. False sharing is one of the major factors that may degrade the performance of memory coherency protocols. This paper presents a new shared memory allocation scheme to reduce false sharing of parallel applications where master processor controls allocation of all the shared objects. Our scheme allocates the objects to temporary address space for the moment, and actually places each object in the address space of processor that first accesses the object later. Its goal is to allocate independent objects that may have different access patterns to different pages. We use execution-driven simulation of real parallel applications to evaluate the effectiveness of our scheme. Experimental results show that by using our scheme a considerable amount of false sharing faults can be reduced with low overhead.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.76-80
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• 1983

In order to investigate the effect of boron and phosphorus for reduction of cold injury of rice, this experiment was undertaken by pot trial. Two levels of phosphorus and 6 levels of boron were applied once at the three stages such as tillering, panicle formation and meiosis stage. Cold water was irrigated to maintain cool temperature ranging 15 to $18^{\circ}C$ from panicle formation stage. It was shown a tendency that three to seven days of early heading were resulted by the 3, 5 and 10kg of boron application per 10 are. The ripening ratio and physiological root activity was rather slightly increased in the above boron levels.