• 정보저장시스템학회논문집
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• 제8권2호
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• pp.72-77
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• 2012

The demand for the laptop computer has been increased day by day and most of users ask quiet computer and devices to work in comfortable environment. One of the devices which generate acoustic noise is an external ODD. Unlike the internal ODD, the external ODD is easy to emit noise because it runs outside of the computer and also it is packed with a thin plastic covers. As the disk rotates, vortex flow is generated inside of the cavity due to various and complicated mold parts of the cover. In addition, there is a gap between the disk tray and the upper/lower cases, through which the air flows as well as the noise leaks. In this study, we have proposed how to reduce the acoustic noise of an external ODD using numerical and experimental analysis. The pressure fluctuations and turbulent kinetic energy distributions are calculated for the developed model. The results show that the sound pressure level is reduced by 2.3dB through simple modifications of ribs of the top cover, which remove or suppress flow instabilities inside of the cavity.

• 한국멀티미디어학회논문지
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• 제13권7호
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• pp.983-990
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• 2010

외부 환경에서의 영상처리 기술은 환경에 매우 민감하여 외부환경이 급격하게 변화할 때마다 정확도가 많이 떨어지는 경향이 있다. 본 논문에서는 다양한 변화가 일어나는 실외환경에서 영상처리 기술을 이용한 방범용 차량 검지 및 추적 시스템을 제안한다. 방범용 카메라검지기는 하나의 차선내에서 차량을 검지하고 추적하기 때문에 차량의 윤곽보다는 차량의 특징 영역을 분리하는 것이 중요하다. 제안한 시스템은 차량 진입의 판단을 광류를 통하여 검지하며, 차량의 전조등, 본넷, 전면창, 루프 등으로 영역을 분류하여 차량을 추적한다. 실험을 통하여 제안한 시스템이 차량의 종류, 속도 및 시간 의 환경 변화에도 강인함을 확인하였다.

• KIEAE Journal
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• 제13권6호
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• pp.93-98
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• 2013

The purpose of this study is to analyze the rate of opening windows that makes residents of a flat-type apartment feel pleasant in summer time. A few conditions were simulated on the wind flow that pass through internal and external spaces of the flat-type apartment, utilizing CFX program. The simulation was made with the criteria for the rates of opening window at 20%, 50%, 70% and 100%. When the rate of window opening was more 50%, the wind speed(more than 1m/s) that makes the residents feel pleasant was observed in more 60% of the internal space. When the all windows of the apartments were opened, the heat island phenomenon was almost disappeared and the pleasant wind flow was more evenly distributed in the external spaces. If residents of apartments recognize the result of this study and practice in agrement on opening windows in summer, it is expected to contribute to minimizing the energy consumption for air conditioning.

• 항공우주시스템공학회지
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• 제14권1호
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• pp.8-15
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• 2020

본 논문은 위성을 발사장까지 안전하게 운반하기 위해, 열이나 외부 온도가 심하게 변화하는 조건에서 위성 컨테이너 내부 온도를 일정하게 유지할 수 있도록 컨테이너 벽면 및 경계층 단열 설계 방법을 제시하고 위성 운반용 컨테이너 외부 환경에 대한 열 유동 해석 및 위성 내부 열 전달 해석을 통해 위성 컨테이너 내부 온도가 일정하게 유지되는지 분석하였다. 컨테이너 내부 유동 해석을 통해 컨테이너 내 위성 주변의 유동이 원활 한지 유동 분포를 확인하였으며, 보조 팬 및 공조시스템과 특별한 그릴 가이드 구조 설계 안을 제시하고자 한다.

• KIEAE Journal
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• 제17권2호
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• pp.5-12
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• 2017

Purpose: Under the purpose of presenting the adequate remodeling period for the improvement of thermal insulation performance of external walls in deteriorated buildings, the change in external wall and residential environment problem(dew condensation) due to aged deterioration after the apartments were constructed in Korea were analyzed. Method: Temperature Difference Ratio Outside(TDRo) and Heat Flow Meter(HFM) were used as measurement methods to evaluate the thermal insulation performance of deteriorated buildings. For TDR evaluation, thermo-graphic camera was used to measure and analyze the surface temperature of external wall. Also, dew condensation evaluation was analyzed using the Temperature Difference Ratio Inside(TDRi). Result: As a result of analyzing thermal performance through TDRo, the first decline point of thermal insulation performance began after 14-16 years have passed since construction was completed, and after 20 years have passed the decline point of thermal insulation performance reappeared. As a result of analyzing U-value with HFM measurement method, the decline rate of external wall's thermal insulation performance is lower than 2% in average at around 5 years after completion, and 8.7% in average at 10-15 years, and over 10.2% in average at 20 years.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.358-363
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• 2008

The spray cross-section characteristics of two-phase spray that using external-mixing nozzle injected into a subsonic cross flow were experimentally studied with various ALR ratio that is $0{\sim}59.4%$. Suction type wind tunnel was used and experiments were conducted to ambient environment. Several plain orifice nozzles with L/d of 30 and orifice diameter of 0.5 mm and orifice length 1.5 mm were tested. Free stream velocity profiles at the injection location were measured using hot wire. Spray images were captured to study collision point and column trajectory. Phase Doppler particle analyzer(PDPA) was utilized to quantitatively measuring droplet SMD, volume flux. Measuring probe of PDPA positions was moved 3-way transverse machine. SMD distributions were layered structure and peaked at the top of the spray plume and low value at bottom of the spray. Volume flux of spray was distributed to the two side region and volume flux quantity decreased when ALR ratio increased. It was found that the perpendicularly injected two-phase spray jet of external mixing into a cross flow showing that mistlike spray moved away from the test section bottom region.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.282-287
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• 2004

Unielement combustion tests were conducted using coaxial bi-swirl injectors. Major experimental parameters were a recess length and a fuel-side swirl chamber. Combustion efficiency mainly depends on a mixing mechanism for the present coaxial swirl injectors. Low-frequency pressure excitations around 200Hz were observed for all injectors. However, dynamic behaviors considerably differ for an external and an internal mixing case controlled by a recess length. The internal mixing induces mixture to be biased at a specific frequency in a mass flow rate, which results in a relatively high amplitude of pressure fluctuations but results for the external mixing case show that fuel and oxidizer mixture flow carries more complicated, multiple wave characteristics due to broad mixing region as well as disintegration and merging phenomena of propellant films.

• 생물환경조절학회지
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• 제3권1호
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• pp.52-57
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• 1994

방울토마토의 수경재배시 과실의 외형형질을 비파괴적으로 추정하고, 이를 검정하였다. ‘Chelseamini’와 ‘뽀뽀’에 비해 ‘Minicarol’의 외형상의 크기(과장, 과폭, 과중, 과실부피)가 특히 작았다. 토마토 과실의 외형형질 간에는 고도의 상관이 인정되어 과실의 생장은 길이생장과 부피생장과 균형있게 이루어지는 것으로 나타났다. 과실의 체적 및 무게는 다음 식으로 추정 가능하였다. 과실의 체적=0.071$\times$(과장+과폭)$^3$＋0.451, 과실의 무게 =0.072$\times$(과장+과폭)$^3$＋0.542. 1993-1994년에 수확한 과실도 이 식으로 설명되었다.

• 한국게임학회 논문지
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• 제17권1호
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• pp.27-40
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• 2017

본 연구는 국내 교육 환경에서 특별하게 등장하고 있는 학습시간 관리서비스의 개념과 그 안에서 활용되고 있는 게이미피케이션 요소들의 특성을 파악한 후, 학습시간 관리서비스가 지향하는 심리적 반엔트로피의 의미와 새로운 게이미피케이션 요소로서 밈(meme)의 역할을 제시한다. 교육용 게이미피케이션의 목표는 게임과 학습의 유사한 부분을 찾아 학습 환경에 접목시킴으로써 학습 동기를 강화하고 몰입으로 이끄는 것이다. 학습시간 관리서비스 또한 그러한 목표를 지향한다. 하지만 그것은 앱 차단과 같은 외적 반엔트로피 환경을 게임적 기술이나 게임적 사고로 연결해 외적 동기를 부여한다는 점에서 차이가 있다. 뿐만 아니라 내적 동기를 유발하기 위해 새로운 게이미피케이션 요소로서 밈을 활용한다는 점에서도 차별화된다. 특히, 학습 패턴과 관련된 밈은 학습 활동 수행에 관한 일종의 지침과 같은 것으로서, 우수한 학습 패턴을 모방하려는 내적 동기를 유발하고 심리적 반엔트로피 상태를 지속시킬 수 있는 동력이 된다. 따라서 학습시간 관리서비스안의 게이미피케이션은 게임 기반의 기술이나 게임적 사고를 활용함으로써 외적 반엔트로피 환경을 강화하고, 학습 패턴의 밈을 활용함으로써 심리적 반엔트로피 상태를 지속시키는 것이다.

• 생태와환경
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• 제45권2호
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• pp.200-209
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• 2012

The current of the water body is very important information for the water quality management on reservoirs. It is applied to hydraulics and water quality model for simulation. In this regard, the current characteristic of water body is the basic information that can be used to predict various conditions. However, it is very slow flowing and is affected by the reservoir operations and external factors. As such, an accurate measurement of the current is a difficult problem. In order to measure the water current, we constructed a drifter. According to the result of flow survey at Yongdam reservoir, 5m and 10 m depth layer flow was investigated from the upstream to the downstream, during a flood period. Maximum flow rate of 5 m depth is 13.8 cm $sec^{-1}$ and 10 m depth shows 4 cm $sec^{-1}$, respectively. But 2m depth shows a backward flow and maximum flow rate is 4 cm $sec^{-1}$. Density currents flow plays the role of back flow in reservoirs. Flow velocity in the reservoir was measured in the range of 1~2 cm $sec^{-1}$, at normal flow season, and the flow direction were different for each survey. This phenomenon occurs because the reservoir volume is very large, compared to the inflow and outflow volume.