• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1106-1111
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• 2006

To improve warpage, delamination and the chemical reaction between 2 different co-fired materials, the bonding behavior with common glass was studied. As shown in the previous paper, the phenomenon of the infiltration is different with the composition of the glass. In particular, in the case of low temperature melting glass, infiltration is experimented in this study. GA-1 glass is infiltrated among $BaTiO_3$ particles below $800^{\circ}C$ and is made by glass/ceramic composite. Until the laminate is fired under $850^{\circ}C$, provskite phase is observed. Although in the case of GA-12 glass, the temperature of the glass infiltration is lower than it of GA-l glass, the perovskite phase already disappears at $800^{\circ}C$. As a result, GA-1 and GA-12 glasses are infiltrated among particles at low temperature, however, the chemical reactivity of the glass/ceramic and sintering temperature should be considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권12호
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• pp.2392-2402
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• 2011

In order to protect some important information communicated through an insecure network, a common hidden key must be used. One can produce the common hidden key using key agreement protocols; and this helps to have high security in modern data networks. Today, the designers of public key cryptography protocols try to set the public identity of a system's users (like their email addresses) as their public key. This not only makes a cryptographic protocol more efficient but also decreases its cost. These protocols are called "identity-based". In this article, an identity-based multiple key agreement scheme will be presented; this scheme uses the challenge-response method to do the verification. While the number of random values produced in our scheme is the same as other schemes, the number of keys generated in this scheme is much more than what many other key agreement schemes produce,. Therefore, we will have less computational complexities campered with other schems. In this paper, we consider the security of our scheme and consequently, we will show that it satisfies many security conditions such as strong security.

• 전력전자학회논문지
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• 제23권5호
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• pp.336-344
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• 2018

This study proposes a new PWM method for leakage current reduction and neutral point (NP) current control in three-phase three-level converter employed in bipolar DC distribution systems. The proposed PWM method uses medium vectors only when there is no need to control the NP current. Thus, common mode voltages are held constant to realize zero leakage current. Some space vectors that produce low-frequency common mode voltages are employed to minimize leakage currents when the average NP current needs to be a positive or negative value. The proposed space vector PWM is implemented based on barycentric coordinate. The validity of the proposed PWM method is verified by simulations and experiments.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2238-2249
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• 2020

In a seismic PSA, dependency among seismic failures of components has not been explicitly modeled in the fault tree or event tree. This dependency is separately identified and assigned with numbers that range from zero to unity that reflect the level of the mutual correlation among seismic failures. Because of complexity and difficulty in calculating combination probabilities of correlated seismic failures in complex seismic event tree and fault tree, there has been a great need of development to explicitly model seismic correlation in terms of seismic common cause failures (CCFs). If seismic correlations are converted into seismic CCFs, it is possible to calculate an accurate value of a top event probability or frequency of a complex seismic fault tree by using the same procedure as for internal, fire, and flooding PSA. This study first proposes a methodology to explicitly model seismic dependency by converting correlated seismic failures into seismic CCFs. As a result, this methodology will allow systems analysts to quantify seismic risk as what they have done with the CCF method in internal, fire, and flooding PSA.

• 한국주거학회논문집
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• 제24권1호
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• pp.1-10
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• 2013

Number of children cared by child care centers has getting up almost half of the from zero to five year age group in korea. Home care children' activities are reported more active and natural than those of center care children. So this study seek the design guidelines for the residential core model of child care centers as second home in korea. The residential core model by Anita Lui Olds was selected and ten domestic center cases were surveyed for guidelines. Firstly, daily-residential core model is learning by daily life at home, and is equiped with cooking kitchenet and group activity area in group room. Secondly, play-residental core model is learning by playing by self, and is equiped with acting, eating and reading common area clustering two or three group room. Thirdly, eco-residental core model is learning by eco-friendly activities, and is equiped with companying, cooperating and sharing area. Fourthly, project-residental core model is learning by project by self, and is equiped with drawing, experimenting and presenting common area. Fifthly, the space of residential core model is organized with three or four group room and clustering living or common area. The larger the center is, the more the cluster is vertically. Facility area and outdoor playground per child is about 7 and $3m^2$.

• Journal of Chest Surgery
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• 제19권3호
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• pp.443-448
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• 1986

Aortic dissection is a serious disease that mortality does not approach to zero despite of medical and surgical improvement. Recently two cases of aortic dissection were treated with good results by the two other methods. Case 1 [57-Y-0-Male]; Chief complaint was chest pain radiating to the back. Preoperatively he was controlled by Minipress, dichlotride, & sodium nitroprusside. Aortography showed DeBakey Type III aortic dissection extending from just below the Lt. subclavian artery to the proximal portion of the origin of the renal artery. Through the midline long incision Flow reversal & Thrombo-exclusion method was used, and bypass course was proximal anastomosis at the ascending aorta - through the Rt. thoracic cavity - midportion of the diaphragm - posterior to the liver, stomach, & pancreas - distal anastomosis at the abdominal aorta proximal to its bifurcation. Bypass graft was preclotted 20 mm Dacron Woven Graft, and the aortic arch between the Lt. subclavian artery & Lt. common carotid artery was divided and meticulously sutured. Control aortogram which was done at 4th postoperative month revealed obstruction of the false lumen by thrombosis, and complications were not noticed. Case 2 [53-Y-0-Male]; Chief complaint was chest pain radiating to the abdomen. DeBakey Type III aortic dissection which was similar to the case 1 was detected by the aortography, and involvement of the Lt. subclavian & common carotid arteries was suspicious. Through the Lt. posterolateral thoracotomy the Ringed Intraluminal Sutureless Graft, No. 22 mm, was inserted from just below the Lt. common carotid artery to the midportion of the descending thoracic aorta under total circulation arrest using a F-F bypass, and the Lt. subclavian artery was ligated. Postoperatively hospital course was uneventful with antihypertensive drugs, and any specific complications were not noticed.

• 대한전자공학회논문지
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• 제25권5호
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• pp.528-535
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• 1988

This paper presents a constructing theory of variable arithmetic operation systems for computing multiplications and multiplicative inverse in GF(2**m) based on a modulo operation of degree on elements in Galois fields. The proposed multiplier is composed of a zero element control part, input element conversion part, inversion circuit, and output element conversion part. These systems can reduce reasonable circuit areas due to the common use of input/output element converison parts, and the PLA and module structure provice a variable property capable of convertible uses as arithmetic operation systems over different finite fields. This type of designs gives simple, regular, expandable, and concurrent properties suitable for VLSI implementation. Expecially, the multiplicative inverse circuit proposed here is expected to offer a characteristics of the high operation speed than conventional method.

• 전기학회논문지P
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• 제61권3호
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• pp.111-115
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• 2012

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensor. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. In this paper, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, in stead of detecting the zero crossing point of the nonexcited motor back electromagnetic force for the average motor terminal to neutral voltage, the commutation signal are extracted directly from the specific average line to line voltage with low-pass filter, adder and comparators circuit. In contrast to conventional methods, the neutral voltage is not need; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. The effectiveness of the proposed method is verified through simulation results.

• 항공우주기술
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• 제13권2호
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• pp.167-176
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• 2014

유로의 개폐를 위해 사용되는 파이로밸브는 가볍고 신뢰성이 높은 장점을 가진다. 미국에서는 하이드라진 추진제를 사용하는 일부 위성 유실의 원인을 착화기 연소 가스의 누설로 판단하였고, 블로우바이라 불리는 이러한 누설 문제를 방지하기 위하여 억지끼워맞춤을 하는 피스톤을 개발하고 추가적인 설계변경을 통하여 신뢰성을 향상하였다. 여기서는 미국에서 수행된 파이로밸브 연구에 대한 문헌조사를 AIAA Paper 위주로 수행하였다. 또한 파이로밸브의 일반적인 문제점과 개선방향, 성능비교평가 사례 등을 다루었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.501-506
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• 1993

An efficient solution algorithm of the optimal load distribution problem with joint torque constraints is presented. Multiple robot system where each robot is rigidly grasping a common object is considered. The optimality criteria used is the sum of weighted norm of the joint torque vectors. The maximum and minimum bounds of each joint torque in arbitrary form are considered as constraints, and the solution that reduces the internal force to zero is obtained. The optimal load distribution problem is formulated as a quadratic optimization problem in R, where I is the number of robots. The general solution can be obtained using any efficient numerial method for quadratic programming, and for dual robot case, the optimal solution is given in a simple analytical form.