• 한국조경학회지
• /
• 제40권2호
• /
• pp.15-23
• /
• 2012

본 연구는 우리나라 초고층 건축물 15개소를 선정하여 토지피복특성과 변화경향을 살펴보고자 하였다. 초고층 건축물 외부공간은 건폐지와 비건폐포장지가 차지하는 비중이 평균 79.7%로 높았으며, 상대적으로 녹지 및 수면이 차지하는 비중은 낮았다. 또한 대부분 지역은 지하개발이 이루어져 조사대상지 평균 생태면적률은 15.90%로 매우 낮은 수준이었다. 준공시기에 따른 피복유형 현황분석 결과, 시간이 지나면서 건폐율이 낮아지고 있었으며, 생태면적률이 증가하고 있었다. 반면, 가장 높은 비중을 차지하고 있는 비건폐포장지의 비율은 통계적으로 차이가 없었다. 초고층 건축물 외부공간의 생태적 기능 개선을 위해서는 포장공간을 줄이는 방안을 강구하는 것이 효과적인 것으로 판단된다.

• Earthquakes and Structures
• /
• 제18권6호
• /
• pp.691-707
• /
• 2020

One of the most important issues in structural systems is evaluation of the margin of safety in low and mid-rise buildings against the progressive collapse mechanism due to the earthquake loads. In this paper, modeling of collapse propagation in structural elements of RC frame buildings is evaluated by tracing down the collapse points in beam and column structural elements, one after another, under earthquake loads and the influence of column removal is investigated on how the collapse expansion in beam and column structural members. For this reason, progressive collapse phenomenon is studied in 3-story and 5-story intermediate moment resisting frame buildings due to the corner and edge column removal in presence of the earthquake loads. In this way, distribution and propagation of the collapse in progressive collapse mechanism is studied, from the first element of the structure to the collapse of a large part of the building with investigating and comparing the results of nonlinear time history analyses (NLTHA) in presence of two-component accelograms proposed by FEMA_P695. Evaluation of the results, including the statistical survey of the number and sequence of the collapsed points in process of the collapse distribution in structural system, show that the progressive collapse distribution are special and similar in low-rise and mid-rise RC buildings due to the simultaneous effects of the column removal and the earthquake loads and various patterns of the progressive collapse distribution are proposed and presented to predict the collapse propagation in structural elements of similar buildings. So, the results of collapse distribution patterns and comparing the values of collapse can be utilized to provide practical methods in codes and guidelines to enhance the structural resistance against the progressive collapse mechanism and eventually, the value of damage can be controlled and minimized in similar buildings.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2001년도 추계학술발표대회 개요집
• /
• pp.33-36
• /
• 2001

• 전자공학회논문지B
• /
• 제30B권12호
• /
• pp.87-97
• /
• 1993

To improve the limitation of fuzzy PI controller when is applied to systems of order higher than one, a fuzzy PI controller that fuzzily resets or amplifies the accumulated control input according to fuzzy rules defined on (error, change of error) space is proposed. The proposed controller structure was motivated by the characteristics of fuzzy PI controller that it generally gives unevitable large overshoot in trial of reducing rise time of response especially when a system of order higher than one is considered. Based on the observation that the undesirable characteristics of the fuzzy PI controller is caused by integrating control input excessively, even though the integrator is introduced to overcome steady state error, we propose a controller that clear out or doubles integrated control input in a fuzzy manner according to the situation to reduce rise time as well as overshoot. To show the usefulness of the proposed controller, it is applied to the systems that are difficult to stabilize or difficult to get satisfactory response by conventional fuzzy PI controllers.

• 음성과학
• /
• 제6권
• /
• pp.145-161
• /
• 1999

21 normal Korean native speakers participated as subjects to investigate the acoustic and aerodynamic study of Korean fricatives and affricates and to make good use of the results for the patients with articulation problems. Their productions of [sa], [s'a], [ca], [$c^{h}a$], [c'a], [asa], [as'a], [aca], [$ac^{h}a$], and [ac'a] were analyzed with CSL and AP II instruments. The results are as followings: (1) Fricatives showed higher frequency in minimum and maximum frequency and longer duration than affricates. (2) Fricatives showed higher peak flow rate and longer rise time than affricates. (3) When we compared the different phonemes with each other, their differences were usually statistically significant, but when we compared CV and VCV syllables, they did not show significant difference, even VCV's showed higher and longer values than CV syllables. (4) Normaly, lax fricatives and affricates showed lower frequency and higher peak flow rate, shorter frication duration, and longer rise time.

• 한국광학회지
• /
• 제17권1호
• /
• pp.23-30
• /
• 2006

폴리머 분산 액정의 전기광학 스위칭 특성에 대한 액정 방울 크기의 효과를 실험적으로 연구하였다. 액정 방울의 크기는 상 분리를 위해 조사하는 레이저 광원의 세기와 LC/oligomer의 혼합 비율에 따라 변화되었다. 전기 광학적 스위칭 전압은 LC/oligomer의 혼합비율과 액정의 방울 크기에 크게 의존하였다. 실험 결과를 보면 상 분리용 조사 레이저광의 세기가 클 때 액정방울의 크기는 작아졌고 포화투과도 전압은 상승했지만 rise time은 짧아 졌다.

• 전자공학회논문지B
• /
• 제30B권5호
• /
• pp.109-119
• /
• 1993

To improve limitations of fuzzy PI controllers especially when applied to systems of order higher than one, we propose a fuzzy PI controller that takes out appropriate amounts of accumulated control input according to fuzzily described situations in addition to the calculation of incremental control input as in the case of conventional fuzzy PI controllers. The structure of the proposed controller was motivated by the characteristics of fuzzy PI controller that it generally gives inevitable overshoot when one tries to reduce rise time of the response especially when a system of order higher than one is under consideration. Since the undesirable characteristics of the fuzzy PI controller is caused by integrator of the controller, even though the integrator is introduced to overcome steady state error of response, we propose a controller that fuzzily clears out integrated quantities according to situation to give reduced rise time as well as small overshoots. To show the usefulness of the proposed controller, it is applied in simulations to such systems as are difficult to stabilize or difficult to get satisfactory responses by conventional fuzzy PI controllers.

• International Journal of Precision Engineering and Manufacturing
• /
• 제8권3호
• /
• pp.8-13
• /
• 2007

A hybrid fuzzy PID controller for a pneumatic chamber is proposed in this paper. First, a mathematical model of a pneumatic pressure servocontrol system was developed where separate implementations of a PID controller and a fuzzy controller were made. The experimental results using a step input signal revealed that the PID controller accurately controlled the steady-state pressure but did not robustly handle parameter variations in the system while the fuzzy controller provided a fast rise time and low overshoot of the pressure in the system. In order to attain the advantages of both the fuzzy and PID controllers, a hybrid control scheme was developed. The experimental results show that the hybrid fuzzy PID controller proposed in this study does indeed possess the advantages of both PID and fuzzy controllers. Hence, it can be concluded that the hybrid fuzzy PID controller is suited for high-precision control of pressure in a pneumatic chamber.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 1999년도 춘계학술발표논문집 논문집
• /
• pp.139-145
• /
• 1999

In current study on 8 college students there was examined modulation of eyeblink (as measured by integrated EMG of m.orbicularis oculi) and skin conductance response (SCR) to an acoustic startle probe (85 dB[A] white noise) by attending to task presented in auditory modality (to memorize words for further recognition) and entire performance of the word recognition test. Both eyeblink magnitude and SCR amplitude and rise time to startle probes were modified (larger magnitude of EMG peak, lower amplitude and shorter rise time of SCR) during attending to task as compared to performance on test. Results are interpreted n terms of modification of electrodermal and eyeblink components of startle and orienting reflexes by task characteristics (passive versus active efforts), attentional demands and aversiveness of experimental situation. However, eyeblink startle response manifested potentiation during attending to task, while SCR demonstrated attenuation. There are discussed implications of startle modulatioas a potentially sensitive probe of situational demands in stress research and also are considered prospects for further studies.

• 한국농공학회논문집
• /
• 제55권3호
• /
• pp.123-128
• /
• 2013

This study was performed to evaluate the slump flow, air content, setting time, compressive strength, adiabatic temperature rise and diffusion coefficient of chloride used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furnace slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performances of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for low carbon green concrete material.