• 대한조선학회논문집
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• 제46권2호
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• pp.114-126
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• 2009

The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz and French 2000, Sirmalis et al. 2001). In order to evaluate manoeuvring motion characteristics of MUUTV, numerical simulation technique has been utilized. Previous mathematical model on manoeuvring motion of MUUTV(Sohn et al. 2006) is basically adopted. Result of static experiment carried out in circulating water channel and a part of NSRDC standard model(Feldman 1979) on rotational mode are supplemented. Some of the hydrodynamic derivatives are obtained from model experiment in circulating water channel and the rest of them are estimated.

• KIEAE Journal
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• 제12권3호
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• pp.53-60
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• 2012

This research is an illustrative research to verify the thermo environmental change created after introduction of indoor pond through abridged model test and simulation analysis. Especially, temperature and comfort level are analyzed by adjusting factors like size of water space, distance length, and location. Summary of the research is as follows. First, the most effective size of water space is 7% of the indoor size, from southern side. Temperature reduction effect is about $1.6^{\circ}C$(5.5%), and for the comfort level, it is found that pmv index increases 8%. Second, based on the simulation of distance length with the sphere, it is more effective as it is close to the surface. If distance length is more than 0.5m, there is no effect on reduction of temperature and comfort level of indoor environment. Lastly, for the analysis by location of the introduced water space, simulation is undertaken by dividing the water space (14% of the indoor size) with front, side, rear and center types. Temperature reduction effect is found to be : front type ($-1.53^{\circ}C$), side type ($-0.82^{\circ}C$), rear type ($-0.44^{\circ}C$), center type ($-0.28^{\circ}C$), respectively. The indoor environment change data by introduction of water space, found in this research, is at initial phase, but it is deemed to be a basic data to refer when planning actual water space.

• 정보와 통신
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• 제31권6호
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• pp.69-74
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• 2014

기후변화에 적극 대처하여 지속적이고 안정적인 용수 공급을 위해 기존의 용수 생산 공급망에 정보통신 기술(Information & Communication Technologies, ICT)을 접목한 지능형 물관리를 위해 '스마트 워터 그리드(smart water grid)'를 구축하고자 하는 다양한 노력이 최근 들어 지속되고 있다. 즉, 스마트 워터 그리드는 기존의 수자원 관리 시스템의 한계를 극복하기 위해 첨단 정보통신기술을 이용하는 고효율의 차세대 인프라 시스템으로 다양한 수원을 활용하고 물을 효율적으로 배분 관리 운송하여 수자원의 불균형을 해소하고, 첨단 센서 네트워크를 이용해 실시간으로 수자원망의 안정성을 모니터링하는 등 용수관리 전분야에 걸쳐 양방향 실시간으로 용수정보를 감시 대응하여 용수관리와 에너지 효율의 최적화된 메가시티(mega-city)에 적합한 지능형 물관리가 가능할 것으로 예상되는 시스템이다. 따라서 본 고에서는 선진화된 상수도시스템 운영을 위해서는 현장설비의 관측값을 감시하고 제어하는 시스템에서, 운영 방식이 변경될 때마다 운영 변수간의 인과관계를 분석하고 예측할 수 있는 시뮬레이션 기능이 탑재된 상수도 운영시스템이 요구되고 있는 실정에서 용수공급 시스템의 운영 상황을 모의할 수 있는 모형 개발 및 용수공급시스템의 운영룰 모의 및 운영의사결정에 적용할 수 있는 다중수원 워터루프 시스템과 운영관리할 수 있는 S/W를 개발 내용을 소개하였다.

• 한국해양공학회지
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• 제20권3호
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• pp.88-95
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• 2006

The resistance characteristics of a trimaran are studied, varying the bottom profile and transom stern of the main hull. The bottom profile is varied in three cases (convex, flat, concave). Using the experimental and numerical methods, the resistance performance of each hull form is compared. The experiments are carried out in ship model basin, and the numerical simulations are performed by a finite-difference method, based on the Marker and Cell scheme. Euler and continuity equationsare used for the governing equations of the flaw field around a trimaran with transom stern. The agreement of both results is good. The optimal bottom profiles for transom stern are presented for law-speed and high-speed regions, respectively.

• 한국도로학회논문집
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• 제16권1호
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• pp.111-118
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• 2014

PURPOSES : This study performs fundamental research on ramp-metering design criteria. METHODS : We carefully review previous studies in terms of ramp-metering design criteria and then consider applicability in Korea. For this, traffic simulation model is employed to analyze actual effect according to specific location of stop-line when implementing ramp-metering. RESULTS : When a stop-line moving forward with a 50m interval, travel speed at mainline relative to current stop-line location tends to decrease. However, traveling speed at approach roads increase about 5~18% under the same condition. When a stop-line location moving backward with a 50m interval, mainline travel speed increase approximately 17~32% whereas traveling speed at approach roads decrease. All cases are compared with the current stop-line location. CONCLUSIONS : We believe that both cases are useful with respect to freeway management. For example, moving forward a stop-line case can be used management for queuing area at ramp section and approach roads. Moving backward a stop-line case can be used for traffic control, focusing on mainline of freeways.

• Journal of the Korean Wood Science and Technology
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• 제22권2호
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.

• Tribology and Lubricants
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• 제27권6호
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• pp.314-320
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• 2011

Although swash-plate type axial piston pumps have the merits of wide operating conditions and high efficiency, the characteristics of pressure pulsation and flow ripple which result in system noise generation are on-going problems. This research examined the analytic models of the dynamic oil pressure and flow characteristics in the pump. A new mathematical model which considered the pressure behaviors of each cylinder and discharge piping was developed to analyze the pump pressure and flow. This model also considered the leakages in the clearances which many researchers have ignored so far. Using the developed model, numerical calculations were implemented. The results showed that widely used simple model which considered only a single cylinder can not predict actual discrete flow dynamics and that fluid inertia effect has to be considered in the mathematical model. Several critical parameters were discussed such as port volume and discharge resistance on the assumption that the pipe length is not so long. The effect of leakages was studied on the final stage.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.367-370
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• 2005

This paper investigated the sound characteristics in an apartment complex. The field measurement was conducted in order to examine the acoustical characteristics of the apartment complex in situ. As a result, it shows that there are around 3 sec. reverberation time and the additional sound reinforcements at the area of high height due to the surrounded buildings. Thus, 1:50 Scale model measurement and Raynoise computer simulation were carried out with insertion of the parapet and the canopy on the balcony. In case of a single building, the parapet was effective to reduce noise level at low floor levels, and the canopy was effective to reduce noise level at high floor levels. But it also shows that both the parapet and the canopy were not effective to reduce noise level at middle floor levels. In case of an apartment complex, the canopy was less effective to reduce noise level at each floor in comparison with case of the single building.

• 수산해양기술연구
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• 제25권1호
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• pp.29-34
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• 1989

이상과 같은 제어계의 구성방법으로 제어계를 설계할 경우에는 오차신호에 대한 PI제어기와 플란트의 상태피이드백을 아울러 행하는 제어계로 됨을 알 수 있으며, 또한 응답 시뮬레이션 결과로부터 알 수 있듯이 본 연구에서 제안하는 방법으로 제어기를 구성할 경우 양호한 제어가 가능하다. Fig.3의 플로우챠트의 그림에서 점선으로 표시된 실시간제어실험의 프로그램은 구성은 되어 있으나 실제로 실험을 행하지 못한 아쉬움이 있으며, 다음 기회에 이 부분의 실험도 행하고자 한다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 춘계학술발표대회
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• pp.985-988
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• 2015

최근 다양한 ICT기술의 발전으로 인간의 사회, 문화, 교육 등의 많은 분야에 변화가 일어나고 있으며, 많은 기술들이 인간 삶의 영역에 적지 않은 영향을 미치고 있다. 그 중에서도 인터넷 웹 표준 기술의 발전은 e-book 시장과 교육용 콘텐츠의 변화가 많을 것으로 예측하고 있다. 따라서 본 논문에서는 N-Screen 지원과 반응형 웹 기술 지원을 위한 3차원 상호작용기반의 e-book 콘텐츠 저작도구 플랫폼 설계를 연구하였으며, 6가지 영역의 상호작용 콘텐츠 개발이 웹 표준에 의해 저작될 수 있는 저작도구 모형을 연구 개발 하였다. 본 논문에서 제안한 e-book의 저작 형태는 웹 표준 기술 HTML5와 ePub3.0 표준을 기반으로 제작할 수 있도록 콘텐츠 플랫폼을 설계 하였으며, 사용자와의 상호작용, 시뮬레이션 등의 기능을 쉽고 빠르게 제작할 수 있는 사용자 인터페이스를 연구 적용하였다. 향후 본 연구의 결과로 전자책 산업 발전과 교육 분야의 활용 향상을 기대하고 있으며, 지식의 체계를 좀 더 다양하게 제공 할 수 있는 e-book 콘텐츠 연구의 원천이 되기를 기대한다.