• 동력기계공학회지
• /
• 제7권2호
• /
• pp.17-22
• /
• 2003

As side-by-side refrigerators came into existence, there has been a growing concern about the free%ins-up of the vital equipment in a walk-in freezer. Due to a bad performance, customers are experiencing too much frustration. In order to minimize the freezing phenomena, the numerical simulation has been performed on the characteristics of cold air flow in a side-by-side refrigerator. The flow field has been simulated with a standard $k-\varepsilon$ turbulent model and a SIMPLE algorithm based on the finite volume method. Through the results of the analysis of the pattern of cold air flow, finally the shape of outlet for cold air flow was modified. The present model was compared with the modified model. The latter was better than the former in minimizing the freezing phenomena.

• 한국산림과학회지
• /
• 제90권1호
• /
• pp.10-18
• /
• 2001

오존 환경에 클론간 감수성을 비교하기 위하여 미류나무(Populus deltoides Marsh.) 10클론을 walk-in type인 4개의 chamber에 대조구, 50ppb, 100ppb, 150ppb 등 4가지 처리로 하루 8시간씩 21일간 계속하여 노출한 후 조기 낙엽율과 잎의 가시적 피해율을 조사하였다. 조기 낙엽율은 처리전과 비교할 때 저농도에서 고농도 순으로 처리농도에 따라 점진적으로 증가하여 150ppb 처리구에서는 50% 이상의 높은 낙엽율을 보였다. 잎의 가시적 피해는 대조구와 50ppb 처리구에서는 나타나지 않았으나, 100ppb 처리구에서는 피해잎 출현율(LA)은 17.3%, 피해면적(AA)은 6.5%로 본당 전체 피해율(LAA)은 1.6%로 나타났고, l50ppb 처리구에서는 피해잎 출현율 34.1%, 피해면적 17.5%로 전체 피해율 7.4%를 보였다. 잎의 가시적인 피해현상이 나타난 100ppb와 150ppb 처리구에서는 클론간에 피해의 차이를 보여 수종내 클론간의 감수성 차이를 확인할 수 있었다.

• International Journal of Internet, Broadcasting and Communication
• /
• 제9권2호
• /
• pp.37-41
• /
• 2017

In the development of means of transportation, human beings who walk, ride or ride carriages are now enjoying the benefits of many means of transportation, including bicycles, airplanes, trains, buses, and cars. In the case of automobiles among various means of transportation, there is an advantage that an individual can conveniently move while possessing it. To solve air polution problems at the same time, eco-friendly automobiles such as low-noise, low-pollution, and high-efficiency automobiles have emerged. However, in the case of eco-friendly vehicleJ, engine noise at low speeds is a noise that is unlike existing vehicles and poses a threat to the safety of pedestrians. In this study, virtual engine system has been developed to prevent engine accidents caused by low- The pedestrians are aware of the fact that the vehicle is approaching.

• 한국대기환경학회지
• /
• 제12권1호
• /
• pp.29-41
• /
• 1996

The two-stage numerical model was used to study the relation between three-dimensional local wind model, advection/diffusion model of random walk method and second moment method on Pusan coastal area. The first stage is three dimensional time-dependent local wind model which gives the wind field and vertical dirrusion coefficient. The second stage is advection/diffusion model which uses the results of the first stage as input data. First, wind fields on Pusan coastal area for none synoptic scale wind showed typical land and sea breeze circulation, and convergence zone occured at 1200LST in northern of domain, in succession, moved northward of domain. Emissions from Sinpyeong industrial district were trasnported toward the inland by sea breeze during daytime, and reached the end part of domain about 1800LST. During nighttime, emissions return to sea by land breeze and vertical diffusion also contributes to upward transport. In order to use this model for forecast of air pollution concentration on the Pusan coastal area, it is necessary that computed value must be compared with measured value and wind fields model must also be dealt in detail.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.847-852
• /
• 2004

The virtual engineering technologies have been broadly used for the design, testing, manufacturing and maintenance works of industrial product. Recently many VR systems with walk through navigation and web databases; such as design and installation database. load history database, maintenance history database et al. are developed. However, the virtual engineering in railroad industry is not well developed compared to other industries like automobile, air, shipbuilding. In this paper, we explain the strategy that we have applied the virtual engineering technology to the design works of rolling stock and our plan to build the virtual testing laboratory(VTL) in the Korea Railroad Research Institute.

• 농업과학연구
• /
• 제25권1호
• /
• pp.33-40
• /
• 1998

The purpose of this study is to suggest objective basic data for Kung-dong neighborhood park management through the quantitative analysis of user's behaviors and satisfaction in Chungnam National University campus forest. Most users lived in Kung-dong, Oun-dong, Shinsung-dong near the campus forest. Their visiting motivations were for taking a walk, health and fresh air. Therefore, it is important that the university should seek a supervision for improving functions of the campus forest. They are using about 300 users per day in campus forest. We should present a supervision programs which make them more useful and protective.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.386-388
• /
• 2007

In many applications of UAVs flying in low altitude, the steady supply of accurate height measurements is very important for the UAVs to complete their mission successfully. In order to do this, a barometer or GPS height measurements are widely used. However, because these two sensors have their limitations in the application environment, a method for fusing these two measurements to produce reference heights are required. In this paper, a reference height generation filter is designed for UAV(Unmanned Air Vehicle) applications. The barometer errors originated by the change of the atmospheric environment are modeled using random walk models, and then the errors are identified and compensated through the ZSB(zero-scan-back) filter algorithm using the GPS height measurements. The performance of the proposed filter is demonstrated by realistic simulations.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1566-1571
• /
• 2003

PGO(Powered Gait Orthosis) mounted with pneumatic muscle as an actuator is upgraded model from RGO(Replicate Gait Orthosis) for paraplegia patients to walk easy and safe. Pneumatic muscles supply powers to both hip joint during PGO gait. The objective of this research is to develop the PGO gait simulation model. Dynamic model of PGO linkage system is processed. Mathematical model of pneumatic muscle was developed and combined it with PGO linkage system. Developed simulation model will be used as a tool for evaluation of the efficiency of pneumatic muscle and for analysis the PGO system.

• 한국환경교육학회지:환경교육
• /
• 제24권1호
• /
• pp.76-87
• /
• 2011

The purpose of this study was to investigate middle school students' perceptions about global environmental problems using drawings. The study was involved the collection of drawing data from 112 ninth grade students from a middle school in Daegu Metropolitan City. The environment task was administrated to students drew a drawing of an global environmental problems and explained their drawing in their own words. Also, students was asked to write what he or she can do to solve global environmental problems. The results are as follows: First, air pollution is the most important global environmental problem, followed by water pollution, global warming, sea level rise, deforestation, waste, loss of biodiversity, and so on. Second, the students' drawings were characterized into two aspects: One is a macroscopic viewpoint and the other is everyday viewpoint. Third, the students' practical action plan to do solve global environmental problems were walk, public traffic, do not throw trash, plant trees, etc. Educators should take into account the perceptions of global environmental problems and teaching-learning strategies to enhance students' understanding of global environment.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.790-793
• /
• 2009

In the case of projection type display, it needs to use the screen in order to project the image clearly and wide viewing angle. We have been developing the step in type display system using the smoke screen. However, the image with smoke screen was flickered by gravity and air flow. Then we considered to reduce the flicker of the image and we found that flicker can be reduced and viewing angle becomes more large. This time we report the large viewing angle step in type display system using screen made up with very small particle size smoke and flow controlled nozzle. Hence, at first we considered the most suitable particle for the screen and then the shape of screen and then we constructed the array of flow controlled smoke screen. By the results of experiment we could get considerably high contrast flicker-less image and get the viewing angle more than $60^{\circ}$ by this flow controlled nozzle attached new type smoke screen and make clear the efficiency of this method.