• The Korean Journal of Physiology and Pharmacology
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• 제17권6호
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• pp.499-503
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• 2013

This study tested the hypothesis that effects of the menstrual cycle on resting blood pressure carry over to dynamic exercise. Eleven healthy females were studied during the early (EP; low estrogen, low progesterone) and late follicular (LP; high estrogen, low progesterone) menstrual phases. Stroke volume (SV), heart rate (HR), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), and total vascular conductance (TVC) were assessed at rest and in response to mild and moderate cycling exercise during EP and LP. During EP, compared to LP, baseline SBP ($111{\pm}1$ vs. $103{\pm}2$ mmHg), DBP ($71{\pm}2$ vs. $65{\pm}2$ mmHg) and mean arterial pressure (MAP) ($84{\pm}2$ vs. $78{\pm}1$ mmHg) were higher and TVC ($47.0{\pm}1.5$ vs. $54.9{\pm}4.2$ ml/min/mmHg) was lower (p<0.05). During exercise, absolute values of SBP (Mild: $142{\pm}4$ vs. $127{\pm}5$ mmHg; Moderate: $157{\pm}4$ vs. $144{\pm}5$ mmHg) and MAP (Mild: $100{\pm}3$ vs. $91{\pm}3$ mmHg; Moderate: $110{\pm}3$ vs. $101{\pm}3$ mmHg) were also higher, while TVC was lower (Mild: $90.9{\pm}5.1$ vs. $105.4{\pm}5.2$ ml/min/mmHg; Moderate: $105.4{\pm}5.3$ vs. $123.9{\pm}8.1$ ml/min/mmHg) during EP (p<0.05). However, exercise-induced increases in SBP, MAP and TVC at both work intensities were similar between the two menstrual phases, even though norepinephrine concentrations were higher during LP. Results indicate that blood pressure during dynamic exercise fluctuates during the menstrual cycle. It is higher during EP than LP and appears to be due to additive effects of simultaneous increases in baseline blood pressure and reductions in baseline TVC.

• 한국전자파학회논문지
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• 제24권11호
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• pp.1055-1063
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• 2013

저 잡음 증폭기는 RF 수신단의 필수적인 요소이며, 다양한 무선시스템에서 사용하기 위하여 넓은 주파수 범위에서 동작하도록 요구된다. 전압 이득, 반사 손실, 잡음 지수, 선형성과 같은 중요한 성능지표들을 신중히 다루어서, 제안하는 LNA의 주요한 성능으로 역할을 하게끔 한다. Buffer 단에서 peaking 인덕터를 사용하며 전체적으로 cascade 구조로써 inductive shunt feedback을 LNA 입력 단에 성공적으로 적용하였다. 광대역 정합 주파수를 얻기 위한 설계식은 상대적으로 간단한 회로구성을 통해 도출된다. 입력 임피던스의 주파수 응답 분석을 위하여 pole과 zero를 광대역 응답을 실현하기 위한 특성으로 기술하였다. 입력 단에 게이트와 드레인 사이의 인덕터는 출력의 3차 고조파를 감소시킴으로 선형성을 크게 향상시킬 수 있다. 제안하는 회로를 $0.18{\mu}m$의 CMOS 공정으로 제작하였고, Pad를 포함한 광대역 LNA의 칩 면적은 $0.202mm^2$이다. 측정 결과는 1.5~13 GHz에서 입력손실은 -7 dB 이하이고, 전압 이득은 8 dB 이상이며, 잡음 지수는 6~9 dB 정도이다. 그리고 IIP3는 8 GHz에서 2.5 dBm이며, 1.8 V 전압에서 14 mA 전류를 소모한다.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.69-78
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• 2011

본 연구에서는 스마트 TMD를 효과적으로 제어할 수 있는 퍼지제어알고리즘을 개발하기 위하여 다목적 유전자알고리즘을 이용한 최적화기법을 제안하였다. 예제구조물로는 풍하중을 받는 76층 벤치마크건물을 선택하였다. 스마트 TMD를 구성하기 위하여 100kN 용량의 MR 감쇠기를 사용하였고, 스마트 TMD의 진동주기는 예제구조물의 1차모드 고유진동주기에 맞추어 조율되었다. MR 감쇠기의 감쇠력은 예제구조물의 풍응답을 최소화할 수 있도록 퍼지제어기를 통해서 조절된다. 퍼지제어기의 입력변수는 75층의 가속도 응답과 스마트 TMD의 변위응답으로 하였고, 출력변수는 MR 감쇠기로 전달되는 명령전압으로 하였다. 퍼지제어기의 최적화를 위하여 다목적 유전자알고리즘인 NSGA-II 기법이 사용되었고, 이때 75층의 가속도 응답과 스마트 TMD의 변위응답을 목적함수로 사용하였다. 최적화 결과, 구조물의 풍응답과 STMD의 변위응답을 동시에 적절히 제어할 수 있는 다수의 퍼지제어기를 얻을 수 있었다. 수치해석을 통해서 스마트 TMD의 성능이 수동 TMD에 비하여 월등히 뛰어남을 알 수 있었고 경우에 따라서는 샘플 능동 TMD보다 더 우수한 제어성능을 발휘하였다.

• 자동차안전학회지
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• 제8권1호
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• pp.31-37
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• 2016

The Child Occupant Safety Assessment was first introduced and carried out by Euro NCAP in 2003, with the goal of ensuring manufacturers to develop safe vehicles for passengers of all ages; the objective was to evaluate the safety and protection offered by different Child Restraint Systems (CRS) in the event of a crash. In 2013, the formerly used P child dummy series was replaced by newer and more biofidelic Q1.5 and Q3 child dummies, representing 1.5 and 3 year old children respectively. The frontal and side impact dynamic performances of the Q1.5 and Q3 were tested within all classes of vehicles assessed by Euro NCAP at the time. As an extension to that initiative, Q6 and Q10 child dummies were later developed representing children of 6 and 10 years old. Since the protection of larger children during vehicle crashes relies greatly on the interaction of vehicle restraint systems such as seat belt and the CRS, instrumented Q6 and Q10 dummies will be used to assess the protection offered in the event of front and side impact crashes. In this paper, we focused on injury criteria of Q6 and Q10 child dummies at 64 kph 40% offset frontal crash test. The whole procedure was designed with DFSS analysis. The full vehicle sled test results of both dummies were conducted with different restraint systems settled through previous sled test. It showed that several injury criteria and image data were collected as the result of the full vehicle sled test. Based on the results of these investigations, this paper describes which factor is most important and combination shows the best performance when evaluating rear seat occupant protection for Q6 and Q10 child dummies.

• 한국지리정보학회지
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• 제20권3호
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• pp.52-66
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• 2017

본 연구는 풍수해 피해예측지도 활용 고도화에 필요한 표준 메타데이터를 시범 설계하고, 이를 기반으로 표준메타정보관리 프로토타입 시스템 구축을 목적으로 하였다. 이를 위해, 국내 외 메타데이터 표준 현황 조사를 통해 가장 활용도가 높은 것으로 분석된 ISO/TC211 19115 국제표준을 기반으로 표준 메타데이터 설계 방향을 설정하였으며, 식별정보, 기준계정보, 배포정보 등 9개의 클래스로 구분하여 메타데이터를 시범 설계하였다. 또한, 본 연구에서 설계한 표준 메타데이터를 바탕으로 메타속성정보를 확인 및 다운로드할 수 있는 표준메타정보관리 프로토타입 시스템을 HTML 기반 JAVASCRIPT 언어로 구축하였다. 본 연구결과를 활용한다면, 표준화된 통합 풍수해 피해예측지도 데이터베이스 구축을 통해 향후 구축되는 피해예측지도의 품질유지가 가능해지며, 풍수해 피해예측 시스템 운영에 필요한 데이터 관리 및 제공 등을 통해 효율적인 재난대응에 활용가능할 것으로 사료된다.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• 통상정보연구
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• 제19권3호
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• pp.83-105
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• 2017

국내외 철강산업의 공급 구조가 변화하는 시기에 중국의 수출 증치세 환급 취소를 전후로 중국 정부의 정책에 즉각적인 영향을 받는 중국산 보통강 H형강, 중국산 보통강 열연강판, 중국산 보통강 후판의 대한국 수출 영향관계를 실증적으로 분석하였다. 중국의 수출 증치세 환급 취소 발표 전에는 중후판의 대한국 수출이 열연강판이나 H형강의 대한국 수출을 선도하는 것으로 나타났으나 발표 후에는 각 변수간 인과관계가 미비했다. 현대제철의 고로 건설로 인한 공급여력 확대와 수요산업의 경기 침체에 따른 철강수입 추세 변화, 중국의 보론강 편법 수출 등의 영향으로 국내 철강시장에 나타난 중국산 철강재의 상호 영향력은 많이 쇠퇴된 것으로 판단된다. 경쟁구조 변화 및 중국산 철강재의 지속적 유입으로 인한 국내 공급증가 위험을 극복하기 위하여 우리 철강산업은 철강재 규격 강화를 통한 국내 철강시장 보호 및 국내 수요가와의 긴밀한 협업을 진행하고 대외적으로 고부가가치화, 해외 고객사와의 중장기 밀착 관리, 수출시장 다변화를 지속적으로 실행해야 한다.

• 한국비블리아학회지
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• 제2권1호
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• pp.132-177
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• 1974

Toe public library may perform a social good only when its objectives are adequate to the community's needs. The present purpose of the public library in the Korean Library Act has no direct concern for our social needs from its very beginning because it was not created in response to our social needs but transplanted from American principles. It is, therefore. difficult to expect socially useful output of our public library programs under the present purpose which may be inadequate to our social tradition and needs. This study purposes to examine validity of the present purpose of the public library in the Korean Library Act, in the light of our community needs and our own library tradition. The methods employed to achieve the purpose of the study are (1) to survey needs of the library frequenters through questionnaire, and interviews with the public librarians in Seoul, (2) to gather the statistical data relevant to, and supporting, the hypothesis, and (3) to compare our social background with that of the United States of which the American purpose, a model for our present purpose, came out. The conclusion is as follows: A. The idea to induce people to pull themselves upward by providing for all the members of the community access to the world's best books shelved in the public library should be abandoned. The reasons are (1) that the idea is alien in our public library tradition, (2) that little demand of the community goes with the idea, and (3) that reading outside the library has come into wide practice, thanks to recent increase in individual income and that in publications. B. That the public library maintains fiction and other recreational reading materials is meaningless in the light of the community needs. These are the two explanations supporting the thesis. (1) The "uplift" theory has proved inoperative and people apparently do not progress from, light fiction to more respectable fare. (2) The conviction that fiction and other recreational reading materials keep the middling classes from the "vicious" entertainments maintaining order in the community by giving them a harmless source of recreation has lost its significance as the modern society provides a number of choices in recreation: television is an obvious example. C. The nature of the informational needs of the community has radically changed, so radically as to require substantial changes in the outlook, collections, and services of the public library, which is :slow in adopting itself to the new social surroundings in Korea. D. 92.2 per Cent of the present frequenters of the public library are high school and college students. Since the library is to meet the existing community needs it should turn its attention to the student group, and develop the means to serve it better, not the "theoretical group of specialists who do not come to "the public library. E. In revision of the purpose of the public library, priority of each objective should be given. The priorities in the last analysis are research and information. culture, recreation in that order.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1400-1418
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• 2020

In the development of commercial promotion, chatbot is known as one of significant skill by application of natural language processing (NLP). Conventional design methods are using bag-of-words model (BOW) alone based on Google database and other online corpus. For one thing, in the bag-of-words model, the vectors are Irrelevant to one another. Even though this method is friendly to discrete features, it is not conducive to the machine to understand continuous statements due to the loss of the connection between words in the encoded word vector. For other thing, existing methods are used to test in state-of-the-art online corpus but it is hard to apply in real applications such as telemarketing data. In this paper, we propose an improved chatbot design way using hybrid bag-of-words model and skip-gram model based on the real telemarketing data. Specifically, we first collect the real data in the telemarketing field and perform data cleaning and data classification on the constructed corpus. Second, the word representation is adopted hybrid bag-of-words model and skip-gram model. The skip-gram model maps synonyms in the vicinity of vector space. The correlation between words is expressed, so the amount of information contained in the word vector is increased, making up for the shortcomings caused by using bag-of-words model alone. Third, we use the term frequency-inverse document frequency (TF-IDF) weighting method to improve the weight of key words, then output the final word expression. At last, the answer is produced using hybrid retrieval model and generate model. The retrieval model can accurately answer questions in the field. The generate model can supplement the question of answering the open domain, in which the answer to the final reply is completed by long-short term memory (LSTM) training and prediction. Experimental results show which the hybrid word vector expression model can improve the accuracy of the response and the whole system can communicate with humans.

• 콘크리트학회지
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• 제10권6호
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• pp.149-159
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• 1998

프리스트레스트 콘크리트 박스 거더 교량의 장기거동의 정확한 예측은 시공중 및 완공후의 사용성 확보를 위해서 매우 중요하다. 이러한 장기거동은 콘크리트의 크리프와 건조수축등의 확률특성에 따라 크게 영향을 받는다. 따라서, 본 논문에서는 프리스트레스트 콘크리트 박스거더 교량에서의 크리프와 건조수축효과의 불확실성 및 민감도 해석에 관한 연구를 수행하였다. 콘크리트의 크리프와 건조수축효과의 불확실성은 입력이자의 변동성을 고려하여 산출한다. 불확실성 및 민감도 해석은 Latin Hypercube 샘플링 기법에 의해 수행하며, 각 샘플에 대하여 시간 의존적 구조해석을 하여 그 결과를 통계학적으로 분석한다. 본 연구에서는 각 입력인자의 구조해석 결과에 대한 민감도를 정량화 하기 위하여 3가지 즉, RCC, PRCC 와 SRCC 상관계수를 사용하여 민감도 해석을 수행하였다. 현재, 주로 교량설계시 사용되는 ACI모델, CEB-FIP모델과 도로교 표준시방서 모델의 민감도 분석을 수행한결과 크리프 모델 자체의 불확실성과 상대습도가 시간에 따른 변형에 가장 중요한 영향인자인 것으로 나타났다. 본 연구에서는 장기거동에 영향을 미치는 주요인자를 도출하는 합리적인 해석기법을 정립하였으며, 이로부터 좀 더 합리적인 모델정립에 유용한 토대가 될 것으로 사료된다.