Earticle

The purpose of this study was to evaluate the structural safety in the Korea Model Greenhouse(1997) to apply the rational and feasible design loads based on the Korea Building Code(2005). It was performed the development of structural system of glass greenhouse using the light weight H section to be new structural system applying to the glass greenhouse. The results of this study were as follows; (1) It was confirmed that the Korea Model Greenhouse(1997) was not guaranteed the structural safety to the new design load. Thus, the Korea Model Greenhouse(1997) had to be modified to adjust the new provisions. (2) In the structural system using the light weight H section, the ALT1 system was the most economic. And if the bay space was 6m, the structural system of light weight H section had the competitive power comparing with the Korea Model Greenhouse(1997).

This paper provides a theoretical rationale for the observed structure of boards, the size and the allocation of board members to monitoring committee (or outside director) and advising committee (or inside director). Also, this paper addresses a new question, a relationship between the quality of a CEO and the board structure. In my model, (1) the monitoring is to …nd precise information for the quality of a CEO, (2) the impact of advising by boards increases with the quality of a CEO (complementarity), and (3) there is "size (capital)-skill complementarity" on the role of a CEO. My model suggests that the size of boards increases with the size of a …rm. The size of board is larger where the …rms face less uncertainty if the uncertainty decreases the informational gain by boards. Finally, when the CEO is expected to be good, the …rms with more uncertainty are more likely to have small boards. Given the size of boards, the …rms with more uncertainty and with talented CEOs allocate the more (less) directors to the advising (monitoring) committee. These predictions well explain the observed variations on boards.

Welding is a representative processing technology applied in many industrial sites due to its quality and convenience. In particular, fiber laser welding can be welded at a faster speed compared to arc welding, and there is an advantage in welding distortion, which is the most significant disadvantage of welding. In this study, the weldable thickness was predicted, and the optimal welding angle was estimated using simulations during the welding of the T-shape structure. The multi-layer heat source model proposed in the previous author's study was used, and the study was conducted using the proposed welding heat source under specific conditions of 4kw and 1.0m/min. As a result, it was predicted that high-quality welding would be possible when the thickness was 3mm or 4mm, and it was also confirmed that welding should be performed at an angle of 82.5° or more when welding a 3mm thick structure. As a follow-up study, we plan to build a welding heat source model under various conditions and conduct a study to derive welding conditions at various thicknesses.

PPS 소자가 삽입된 부분웰 구조의 N형 실리콘 제어 정류기(NSCR_PPS) 소자에서 정전기 보호 성능의 향상을 위한 CPS 이온주입 조건의 최적화에 대해 연구하였다. 종래의 NSCR 표준소자는 on-저항, 스냅백 홀딩 전압 및 열적 브레이크다운 전압이 너무 낮아 정전기 보호소자의 필요조건을 만족시키지 못해 적용이 어려웠으나, 본 연구에서 제안하는 CPS 이온주입과 부분웰 이온주입을 동시에 적용한 변형 설계된 소자의 경우 스냅백 홀딩 전압을 동작전압 이상으로 증가시킬 수 있는 향상된 정전기 보호성능을 나타내어 고전압 동작용 마이크로 칩의 정전기보호 소자로 적용 가능함을 확인하였다

The ESD(electrostatic discharge) protection performance of PPS(PMOS pass structure) embedded N-type silicon controlled rectifier(NSCR_PPS) device with different partial p-well(PPW) structure was discussed for high voltage I/O applications. A conventional NSCR_PPS standard device shows typical SCR-like characteristics with low on-resistance, low snapback holding voltage and low thermal breakdown voltage, which may cause latch-up problem during normal operation. However, our proposed NSCR_PPS devices with modified PPW_PGM(primary gate middle) and optimal CPS(counter pocket source) implant demonstrate the stable ESD protection performance with high latch-up immunity.

In drawing area, aiming at the problems of drawing breadth and angle cannot be adjusted individually and not convenient to carry, a kind of multi-functional folding drawing board is designed by us. The appearance of the multi-functional folding drawing board is kind of drawing board, some light materials like basswood and rigid plastics are used in main structure of the drawing board to make it light and convenient to carry. The main structure can be folded and it is suitable for A1 and A2 drawings. In the designing procedure, dip angle adjusted mechanism by worm wheel and gear, magnetic pull-in mechanism, leading rail, slide-way, drawer, tool library, paper bag and horn locks are applied based on modularity designing theory. Finite element analysis of key components of drawing board is analyzed.

In view of the bias of panel data model set can lead to misjudgment to the relationship between enterprise value and the capital structure, this article uses nonparametric method to study the relationship between them, adjusts variables in the model. The article evaluates the optimal capital structure of listed companies of the equipment manufacturing industry in our country Based on financial data from 2006 to 2013, analyzes from the Angle of enterprise value and agency cost respectively,. The results show that, The relationship between enterprise value and capital structure is inverted u-shaped, there exists a maximum asset-liability ratio in enterprise value. And the relationship between agency cost and capital structure present u-shaped roughly, there is a minimum asset-liability ratio in agency costs, there is a reasonable capital structure interval when asset-liability ratio is in range (32.87%, 58.21%).

Protein includes many substances, such as enzymes, hormones and antibodies that are necessary for the organisms. These proteins have different shapes and structures which distinct them from each other. By having unique structures, only proteins able to carried out their function efficiently. The importance of understanding protein structure has fueled the development of protein structure databases and prediction tools. The main objective of this research is to optimize local protein structure with Support Vector Machine (SVM) to predict protein secondary structure. Most of the related study used fixed segment length for secondary structure prediction and this might produce inaccurate results. In this research, dataset is segmented into different segment length of local protein structure. An optimal length of local protein structure is determined and the evaluation is carried out by comparing with the existing methods and initial prediction using native structure. Higher accuracy and true positive rate, low false positive rate are obtained which prove the effectiveness of this prediction method. A statistical method, t-test, is applied to validate the results of the prediction.

As for control systems, many researchers give optimal structures of the finite-word-length compensator. D. Williamson solved a fixed-point case against colored noise for the LQG problem. Recently, one of the authors derived an optimal filter against colored noise. And consequently, we apply the result to a twodegree-of-freedom control system in this paper. In addition the perturbation of the coefficients is considered. Furthermore, simulation results indicate this method gives better than other structures.

This study starts with a question on two related, unverified assumptions about the cognitive or psychological concept of coherence in discourse: the definition of textual coherence is so abstract and varied that it may be rated differently by language users with different language backgrounds, and that it does not explicitly reveal its overall shape on the surface of text. We conduct an experiment with three stages on 33 argumentative essays written by native and non-native speakers of English: ratings of coherence, distribution and organization of coherence proper Linking Adverbials (LAs). The results show that there is quite a consistent pattern in 10 international raters’ assessment on textual coherence of the essays. The difference in the pattern of arranging coherence proper LAs between the high and low group reveals the optimal arrangement of coherence proper LAs, which is assumed to work to the effect that maximizes the cognitive concept of coherence.

In the recent past, genetic algorithm (GA) and evolutionary optimization scheme have become increasingly popular for the design of electromagnetic (EM) devices. However, the conventional GA suffers from computational drawback and parameter dependency when applied to a computationally expensive problem, such as practical EM optimization design. To overcome these issues, a hybrid optimization scheme using GA in conjunction with Kriging is proposed. The algorithm is validated by using two mathematical problems and by optimizing rotor structure of interior permanent magnet synchronous machine.

하나의 reader가 tag의 군집에 둘러싸여 있는 별 형태의 RFID 망을 고려한다. 이러한 RFID 망에서 reader는 tag에 저장된 정보를 얻기 전에 tag의 응답 간 충돌을 중재하면서 tag를 인식하여야 한다. 이러한 목적으로 tag가 응답하도록 프레임마다 정적으로 일정 수의 슬롯을 마련해 주는 프레임화 및 슬롯화된 ALOHA에 기반한 tag 인식 방식을 제안한다. 제안 방식의 인식성능을 평가하기 위해 주요 성능 척도로 인식 완료 확률과 기대 인식 완료 시간을 선정한다. 이어서 이러한 성능 척도를 계량적으로 계산할 수 있는 방법을 제안한다. 특히 tag가 많지 않은 경우 성능 척도를 closed form으로 도출한다. 다음 인식 시간에 대한 제약 하에서 인식 완료 확률을 최대화하거나 기대 인식 완료 시간을 최소화하는 최적의 시간 구조를 찾는 문제를 구성한다. 마지막으로 이러한 문제를 풀어서 프레임 당 tag가 응답하기 위한 슬롯의 최적 수를 구한다. 계량적 결과로부터 tag가 응답하기 위한 슬롯의 유한한 최적 수가 존재함을 확인한다. 또한 인식 완료 확률을 최대화하는 최적 슬롯 수는 인식 시간에 대한 제약이 약해지면서 기대 인식 완료 시간을 최소화하는 최적의 슬롯 수로 접근하는 경향을 보임을 관찰한다.

Consider an RFID network configured as a star such that a single reader is surrounded by a crowd of tags. In the RFID network, prior to attaining the information stored at a tag, the reader must cognize the tags while arbitrating a collision among tags' responses. For this purpose, we present a tag cognizance scheme based on framed and slotted ALOHA, which statically provides a number of slots in each frame for the tags to respond. For the evaluation of the cognizance performance, we choose the cognizance completion probability and the expected cognizance completion time as key performance measures. Then, we present a method to numerically calculate the performance measures. Especially, for small numbers of tags, we derive them in a closed form. Next, we formulate a problem to find an optimal time structure which either maximizes the cognizance completion probability under a constraint on the cognizance time or minimizes the expected cognizance completion time. By solving the problem, we finally obtain an optimal number of slots per frame for the tags to respond. From numerical results, we confirm that there exist a finite optimal number of slots for the tags to respond. Also, we observe that the optimal number of slots maximizing the cognizance completion probability tends to approach to the optimal number of slots minimizing the expected cognizance completion time as the constraint on the cognizance time becomes loose.

This study focuses on investigating the existence of optimal capital structure for firms listed in KOSPI stock market by employing inter- and intra-industry analyses. To date, very little attention seems to be paid to this subject in modern finance, considering that a firm’s value is increases as it approaches its optimal level of financial leverage. Moreover, it attempts to identify one of the most relevant theories which significantly accounts for the existence of a firm’s optimal capital structure. Relevant theory such as Myers’ pecking order was contemplated to postulate a corresponding hypothesis. Concerning the empirical methodologies to test for a hypothesized existence of an optimal capital structure, analysis of variance and analysis of covariance models were separately utilized in the context of parametric and nonparametric statistical approaches. Results suggested that an optimal level of capital structure for KOSPI-listed firms at the intra-industry level does not exist. However, differences in leverage were pronounced among 24 sample industries, which may suggest that optimal levels of capital structure appear to exist in the Korean capital market at the inter-industry level.

In this paper, a design of an integral augmented nonlinear optimal variable structure system(INOVSS) is presented for the prescribed output control of uncertain MIMO systems under persistent disturbances. This algorithm basically concerns removing the problems of the reaching phase and combining with the nonlinear optimal control theory. By means of an integral nonlinear sliding surface, the reaching phase is completely removed. The ideal sliding dynamics of the integral nonlinear sliding surface is obtained in the form of the nonlinear state equation and is designed by using the nonlinear optimal control theory, which means the design of the integral nonlinear sliding surface and equivalent control input. The homogeneous $2{\upsilon}(\kappa)$ form is defined in order to easily select the $2{\upsilon}$ or even $(\kappa)-form$ higher order nonlinear terms in the suggested sliding surface. The corresponding nonlinear control input is designed in order to generate the sliding mode on the predetermined transformed new surface by means of diagonalization method. As a result, the whole sliding output from a given initial state to origin is completely guaranteed against persistent disturbances. The prediction/predetermination of output is enable. Moreover, the better performance by the nonlinear sliding surface than that of the linear sliding surface can be obtained. Through an illustrative example, the usefulness of the algorithm is shown.

본 연구는 불확실성이 존재하는 다이나믹 시스템을 고 강인성 및 성능 사전 결정 제어를 하기 위하여 적분 최적 가변구조 시스템을 설계한다. 제안된 제어기에서는 적분 슬라이딩 면을 이용 리칭 문제를 완전히 제거하여 시스템이 초기 값에서부터 바로 슬라이딩하여 외란과 불확실성에 무관하게 사전에 결정된 슬라이딩 면을 슬라이딩 모드 상태로 추종하므로 고 강인성 제어가 이루어진다. 적분 슬라이딩 면이 정의하는 이상 슬라이딩 동특성을 상태방정식 형으로 얻고, 고급 최적 제어 이론을 통하여 최적 의미로 설계한다. 이는 바로 슬라이딩 면과 등가 제어입력의 설계가 된다. 사전에 선정된 슬라이딩 면 위에 슬라이딩 모드를 발생할 제어입력을 설계하였다. 그 결과 외란과 불확정성에도 불구하고 주어진 초기 값에서부터 원점까지 전체 슬라이딩 출력이 완전하게 보장받는다. 더구나 기존의 최적 VSS에서는 설계 성능의 강인성을 보장받기 어려운데 반하여, 제안된 IOVSS에서는 실제 출력의 예측과 사전 결정이 가능하다. 예제를 들어 제안된 알고리듬의 성능을 검진한다.

In this paper, a design of an integral augmented optimal variable structure system(IOVSS) is presented for the prescribed output control of uncertain SISO systems under persistent disturbances. This algorithm aims at removing the problems of the reaching phase by incorporating advanced optimal control theory. By means of an integral sliding surface, the reaching phase is completely removed, and the integral sliding surface can be defined from a given initial state to origin without any reaching phase. The ideal sliding dynamics of the integral sliding surface is obtained in the form of the state equation and is designed in an optimal sense by targeting the design of the integral sliding surface and equivalent control input. The corresponding control input is selected in order to generate the sliding mode on the predetermined integral sliding surface. As a result, the whole sliding output from a given initial state to origin is completely guaranteed against persistent disturbances. Moreover the prediction/predetermination of output is enabled, which helps in improving the performance over previously implemented VSS's. Through an illustrative example, the usefulness of the algorithm is shown.

This paper investigates implications of the static tradeoff theory and the pecking order theory. The results suggest that firms adjust their debt levels according to target debt ratios as well as the pecking order. By combining the two theories, the research finds that firms are more likely to increase debt when they face financing needs as well as below-target debt level, while they are more likely to decrease debt level when they have surplus cash flows as well as above-target debt level. The pecking order is found to be a much more bindingforceforsmallfirms, supportingthehypothesisthatsmallfirmsaremorelikelytofollowthepecking order because o f the difficulty in accessing external financing sources due to asymmetric information. The research also finds that small firms are significantly slower than large firms in adjusting the debt level when the adjustment requires an increase in debt level according to the target adjustment model.

This paper proposes an optimum, problematic design for structural and control systems, taking a 3-D truss structure as an example. The structure is subjected to initial static loads and time-varying disturbances. The structure is controlled by a state feedback H$_{\infty}$ controller which suppress the effects of disturbances. The design variables are the cross sectional areas of truss members. The structural objective function is the structural weight. For the control objective, we consider two types of performance indices, The first function represents the effect of the initial loads. The second function is the norm of the feedback gain, These objective functions are in conflict with each other but are transformed into one control objective by the weighting method. The structural objectives is treated as the constraint, By introducing the second control objective which considers the magnitude of the feedback gain, we can create a design to model errors.

A controller of interconnected power systems is investigated using an optimal multidimensional variable structure control. The switching hyperplane of the variable structure stabilizer is obtained by minimizing a quadratic performance index in continuous-time. A special feature of the optimal multidimensional variable structure stabilizer is that, when it is operated in the so-called sliding mode, the system response becomes insensitive to changes in the plant parameters. A digital simulation is performed by a digital computer using the Advanced Continuous Simulation Language (ACSL) package, which shows that the dynamic performance of the power system in response to mechanical torque changes is improved when optimal multidimensional variable sturcture stabilizers are employed.