• 설비공학논문집
• /
• 제13권12호
• /
• pp.1255-1265
• /
• 2001

A numerical study has been conducted to characterize the transient flow in a utility gas turbine burning natural gas. The solution domain encompasses the supply gas pressure regulator to the combustor of the gas turbine that employs multi-nozzle fuel injectors. Some results produced for verification in the present study agree suite well with the experimental ones. It is found that the total gas flow may decrease noticeably during its combustion mode change, which would be the reason of momentary combustion upset, when a reference case of opening ratios of control valves in the system is applied. Several parameters are then varied in order to make the total gas flow stable over that period of time. Results of this study may be useful to understand the unsteady behavior of combustion system burning natural gas.

• 한국정밀공학회지
• /
• 제25권5호
• /
• pp.121-131
• /
• 2008

In this paper, the dynamic stability of a cracked simply supported pipe conveying fluid with an attached mass is investigated. Also, the effect of attached masses on the dynamic stability of a simply supported pipe conveying fluid is presented for the different positions and depth of the crack. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by the energy expressions using extended Hamilton's principle. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The crack is assumed to be in the first mode of a fracture and to be always opened during the vibrations. Finally, the critical flow velocities and stability maps of the pipe conveying fluid are obtained by changing the attached masses and crack severity. As attached masses are increased, the region of re-stabilization of the system is decreased but the region of divergence is increased.

• East Asian Economic Review
• /
• 제22권4호
• /
• pp.531-555
• /
• 2018

This article aims to review the monetary policy rule under inflation targeting framework focusing on Mongolia. The empirical analysis estimates the policy reaction function to see if the inflation targeting has been linked with a monetary policy rule emphasizing on inflation stabilization since its adoption in 2007. The study contributes to the literature by examining the linkage between Mongolian monetary policy rule and inflation targeting directly and thoroughly for the first time and also by taking into account a recent progress in the inflation targeting framework toward forward-looking mode. The main findings were: the Mongolian current monetary policy rule under inflation targeting is characterized as inflation-responsive rule with forward-looking manner (one quarter ahead); the inflation responsiveness is, however, weak enough to be pro-cyclical to inflation pressure; and the rule is also responsive to exchange rate due to the "fear of floating", which weakens the policy reaction to inflation and output gap.

• 한국농공학회지
• /
• 제34권4호
• /
• pp.69-79
• /
• 1992

To estimate soil behavior and structural characteristics under the conditions of cyclic loading, freezing & thawing and initial state, several testing was performed and obtained following results. 1.After repeated freezing and thawing processes, original soil structure was destroyed and changed to globular structure from honeycomb or tube in its structure types. Also above processes resulted increasing the soil compression strain while decreasing the failure stress in stress-strain relationship and reached the soil structure into the mode of brittle fracture. Under cyclic loading conditions, soil cluster which was originally dispersed structure colloided with each other, seperated, and finally the soil failed due to the effect of overcompaction. 2.Through the stabilization processes seperated by four steps, the structure of soil skeleton was changed to quite different globular type. The degree of compressibility of soil was decreased in the normally consolidated zone, while the strength against external load increased due to soil particle stabilization. 3.Soil stress-strain chracteristics were largely influenced by repeated up and down processes of temperature. The maximum deformation was obtained in the case of temperature between 0 10˚C by the reseon of particle cluster reformation. 4.Soil compressibility was largely influenced by the optimum moisture content. Under freezing process, swelling could be found and its magnitude was proportional to the density of soil. 5.Density of soil was decreased as increasing the number or repeated freezing and thawing processes and the largest decreasing rate was found at the first turning point from freezing to thawing cycle.

• Journal of Korean Neurosurgical Society
• /
• 제37권2호
• /
• pp.89-95
• /
• 2005

Objective: The biomechanical stabilities between the anterior plate fixation after anterior discectomy and fusion (ACDFP) and the posterior transpedicular fixation after ACDF(ACDFTP) have not been compared using human cadaver in bilateral cervical facet dislocation. The purpose of this study is to compare the stability of ACDFP, a posterior wiring procedure after ACDFP(ACDFPW), and ACDFTP for treatment of bilateral cervical facet dislocation. Methods: Ten human spines (C3-T1) were tested in the following sequence: the intact state, after ACDFP(Group 1), ACDFPW(Group 2), and ACDFTP(Group 3). Intervertebral motions were measured by a video-based motion capture system. The range of motion(ROM) and neutral zone(NZ) were compared for each loading mode to a maximum of 2.0Nm. Results: ROMs for Group 1 were below that of the intact spine in all loading modes, with statistical significance in flexion and extension, but NZs were decreased in flexion and extension and slightly increased in bending and axial rotation without significances. Group 2 produced additional stability in axial rotation of ROM and in flexion of NZ than Group 1 with significance. Group 3 provided better stability than Group 1 in bending and axial rotation, and better stability than Group 2 in bending of both ROM and NZ. There was no significant difference in extension modes for the three Groups. Conclusion: ACDFTP(Group 3) demonstrates the most effective stabilization followed by ACDFPW(Group 2), and ACDFP(Group 1). ACDFP provides sufficient strength in most loading modes, ACDFP can provide an effective stabilization for bilateral cervical facet dislocation with a brace.

• 한국항공우주학회지
• /
• 제36권7호
• /
• pp.712-718
• /
• 2008

본 논문은 비행 중 비행제어법칙을 전환함으로써 실험 대상 비행제어법칙을 검증할 수 있는 비행제어법칙 전환시스템 개발에 관한 논문이다. 본 연구를 통하여 제어법칙 간 전환에 따른 천이응답을 최소화하기 위한 페이더 설계 및 대기 모드 상태에 있는 비행제어법칙의 적분기 안정화 설계가 도입되었다. 두 개의 제어법칙 간 데이터 통신은 1553 통신 방식을 채택하였다. 본 논문은 개발된 비행제어법칙 전환시스템의 구조 및 주요 개념 설계 연구 및 고등훈련기급의 비행성 평가 시뮬레이터를 이용한 시스템 검증 결과를 포함한다.

• 폴리머
• /
• 제30권1호
• /
• pp.35-44
• /
• 2006

폴리(비닐 알코올)을 콜레스테릴 클로로포메이트 또는 8-콜레스테릴옥시카보닐헵타노일 클로라이드(CH8C)와 반응시킴에 의해 폴리[1-(콜레스테릴옥시카보닐옥시)에틸렌](PCOE)와 폴리[1-콜레스테릴옥시카보닐헵타노일옥시)에틸렌](PCOSE)를 합성함과 동시에 이들의 열 및 광학 특성을 검토하였다. CH8C는 단방성 콜레스테릭 상을 형성하는 반면 PCOE와 PCOSE는 쌍방성 콜레스테릭 상들을 형성하였다. CH8C의 경우와 같이, PCOSE의 광학피치$(\lambda_m)$는 온도가 상승함에 따라 감소하였다. PCOE는 PCOSE와 달리 반사색깔을 나타내지 않았다. 이러한 사실은 콜레스테릴 그룹에 의한 나선의 비틀림력은 콜레스테릴 그룹과 주사슬을 연결하는 스페이서의 길이에 민감하게 의존함을 시사한다 PCOE와 PCOSE가 나타내는 액정 특성들은 폴리(콜레스테릴-$\omega$-아크릴로일옥시알카노에이트들)이 나타내는 액정 특성들과 전혀 다르다. 이러한 결과들은 곁사슬과 주사슬의 화학결합의 양식이 콜레스테릭 상의 형성능, 안정성 그리고 $\lambda_m$의 온도 의존성에 중요한 역할을 함을 시사한다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.414-414
• /
• 2007

In this study, Liquid Crystal (LC) alignment and tilt angle generation in Nematic Liquid Crystal (NLC) with negative dielectric anisotropy on the homeotropic PI surface with new ion beam exposure are reported. Also. high density of ion beam energy (DuoPIGatron type Ar ion gun) is used in this study. The tilt angle of NLC on the homeotropic Polyimide (PI) surface for all incident angles is measured about 38 degree and this has a stabilization trend. And the good LC alignment of NLC on the PI surface with ion beam exposure of $45^{\circ}$ incident angle was observed. Also the tilt angle of NLC on the homeotropic PI surface with ion beam exposure of $45^{\circ}$ had a tendency to decrease as ion beam energy density increase. The tilt angle could be controlled from verticality to horizontality. Also, the LC aligning capabilities of NLC on the homeotropic PI surface according to ion beam energy has the goodness in case of more than 1500 eV. Finally. the superior LC alignment thermal stability on the homeotropic PI surface with ion beam exposure can be achieved. For OCB(Optically Compensated Bend) mode driving, we can need pretilt angles control for fast response time. In this study, We success pretilt angles control. Consequently, this result can be applied for OCB mode.

• 한국자동차공학회논문집
• /
• 제22권6호
• /
• pp.59-67
• /
• 2014

A numerical model and a controller of Active Front wheel Steer (AFS) system are designed in this study. The AFS model consists of four sub models, and the AFS controller uses sliding mode control and PID control methods. To test this model and controller an Integrated Dynamics Control with Steering (IDCS) system is also designed. The IDCS system integrates an AFS system and an ARS (Active Rear wheel Steering) system. The AFS controller and IDCS controller are compared under several driving and road conditions. An 8 degree of freedom vehicle model is also employed to test the controllers. The results show that the model of AFS system shows good kinematic steering assistance function. Steering ratio varies depends on vehicle velocity between 12 and 24. Kinematic stabilization function also shows good performance because yaw rate of AFS vehicle tracks the reference yaw rate. IDCS shows improved responses compared to AFS because body side slip angle is also reduced. This result also proves that AFS system shows satisfactory result when it is integrated with another chassis system. On a split-m road, two controllers forced the vehicle to proceed straight ahead.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.159-161
• /
• 2007

$CO_2$ laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400ums laser beam in rain focus sacred ground surroundings cellular tissue without vitiation me by evaporation Poe of very small floor as is clean steam can. Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can. Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.