• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 춘계학술대회 논문집
• /
• pp.615-620
• /
• 2005

The purpose of this study was to provide a criterion of ballast aggregate size distribution for paved track. The parameters considered in this study were different types of particle size distribution. Then the analysis for analyzing compressive and flexural strength, physical characteristics of aggregate, and the ballast box test were performed. In the test result of the physical characteristic performed by the ballast box test, the bearing capacity was measured lower than the expected value because of its boundary conditions. Among four types of ballast aggregate, type B was selected as one of best candidate distribution because of its bearing capacity, strength, development and economics.

• 대한교통학회지
• /
• 제32권6호
• /
• pp.579-588
• /
• 2014

본 연구는 자전거 좌회전 교통류를 수용한 신호교차로 운영방안으로 Bike Box, Hook-turn, 그리고 6현시의 3가지 방식을 다양한 교통상황 및 조건하에서 평가하였다. 분석결과, Bike Box방식과 Hook-turn 방식 모두 대기공간의 크기가 신호운영 결과에 큰 영향을 미치는 것으로 파악되었다. 비포화와 근포화 교통상황에서 Hook-turn과 Bike Box방식은 자동차지체 차이는 거의 없으나 자전거 지체는 Hook-turn이 Bike Box 방식에 비해 2.5-29.9초/대 높게 나타났다. 6현시 방식은 Bike Box 방식에 비해 자동차와 자전거 지체가 모두 매우 크게 나타났다. 포화 교통상황에서는 Bike Box방식이 Hook-turn과 6현시운영에 비해 자동차지체는 작게 나타났으나, 자전거지체는 자전거 교통량이 700대/시에서 6현시 방식보다 오히려 증가하였다. 자전거지체는 Hook-turn방식은 자전거교통량이 300대/시 이후, Bike Box방식은 500대/시 이후부터 지체가 급격하게 증가하였다. 그리고 Bike Box와 Hook-turn 방식 모두 대기공간이 증가시 자전거 지체가 매우 큰 폭으로 감소하였다. 또한 동-서 및 북-서 교통량 패턴 모두 Bike Box가 Hook-turn 방식보다 자동차와 자전거 지체가 작게 나타났다.

• 한국식품저장유통학회지
• /
• 제10권4호
• /
• pp.466-469
• /
• 2003

콜드체인용 골판지 상자의 냉기공과 상자의 압축강도와의 관계를 알아보고자, 골판지 상자에 각각 냉기공을 2 또는 3개를 뚫고, 냉기공의 크기와 면적을 달리하여 상온(RH 70$\pm$5 %)에서 4주간 저장하면서 골판지 상자의 압축강도를 측정하였다. 냉기공 면적이 4, 7, 10 %모두에서 냉기공의 크기가 폭은 좁고 길이가 긴 것이 압축강도가 높게 나타났다. 또한 냉기공 면적에 따른 압축강도를 살펴보면 냉기공 면적이 4 %인 상자가 다른 상자들에 비해 압축강도가 10 %이상 높게 나타났다. 하지만 냉기공 수에 따른 상자의 압축강도는 냉기공 2개와 3개간에 10 %미만의 압축강도 차이를 보여, 골판지 상자의 압축강도를 높이기 위해서는 냉기공이 차지하는 면적을 줄이고 냉기공의 모양은 폭이 좁고 길이는 길게 하는 것이 바람직할 것으로 판단되었다.

• Journal of Biosystems Engineering
• /
• 제20권4호
• /
• pp.351-359
• /
• 1995

In pressure cooling system, produce were packed in vented box and cooled rapidly by producing a difference in air pressure on opposite faces of stacks of vented box. So, energy requirements and performance of pressure cooling system depended upon the air flow rate and the static pressure drop through packed produce in vented box. The static pressure drop across packed produce in vented box normally depended upon air flow rate, vent area of box and conditions of produce bed (depth, porosity, stacking patterns, size and shape of products) in box. The objectives of this study were to investigate the effect of vent area and air flow rate on airflow resistance of empty box and packed produce in vented box, and to investigate the relationship between the air flow resistance of packed products in vented box and sum of air flow resistance of empty box only and products in bulk only. Mandarins and tomatoes were used in the experiment. The airflow rate were in the range of 0.02~1.0$m^3$/s.$m^2$, the opening ratio of vent hole were in the range of 2.5~20% of the side area. The results were summerized as follows. 1. The pressure drops across vented box increased in proportion to superficial air velocity and decreased in proportion to opening ratio of vent hole. A regression equation to calculate airflow resistance of vented box was derived as a function of superficial air velocity and opening ratio of vent hole. 2. The pressure drops across packed produce in vented box increased in proportion to superficial air velocity and decreased in proportion to opening ratio of vent hole. 3. Because of the air velocity increase in the vicinity of vent hole in box, the airflow resistances of packed products in vented box were always higher than sum of air flow resistance of empty box only and products in bulk only. 4. Based on the airflow resistance of empty box and products in bulk, a regression equation to calculate airflow resistance of packed products in vented box was derived.

• 한국자동차공학회논문집
• /
• 제16권2호
• /
• pp.136-142
• /
• 2008

Thermal management of a junction box of a passenger car has recently become more challenging due to its smaller size and larger current capacity. Thus, it is essential to perform the thermal optimization of a junction box in its design on an early stage of vehicle design. In this study, 3 dimensional CFD simulation with experimental measurement has been done to study for better thermal management of the junction box. First, the study of thermal characteristics of electric relays in the junction box has revealed that each surface of the relay has very different thermal resistance. In addition, an idea to install a cooling fan on the junction box has been studied and it was found that the forced cooling method was not effective on the system to keep the thermal resistance to the reasonable level of the junction box. Finally, the effect of external flows around the junction box on the temperatures of the relays, fuses, etc. has been studied and the result shows that the installation of the junction box at the proper place in an engine room can avoid any unnecessary overdesign in thermal management.

• 천문학회보
• /
• 제38권1호
• /
• pp.66.2-66.2
• /
• 2013

In this study, we present a pore-selection technique to estimate the size of pore. The estimation of the size of pore is important to examine the temporal evolution of size itself and corresponding intensity. The size of pore is typically estimated by applying the intensity threshold technique to the fixed box which contains the entire pore. The typical method has disadvantages in the following circumstances; there are small features near the pore or the image has low spatial resolution. In the former, it is difficult to define a box containing the pore only, excluding the small features near the pore. In the latter, the background and threshold intensity are insignificant due to the insufficient number of pixel in the box. To avoid these difficulties, we use a pore-selection technique which is simply based on the measurement of distances from the pore center. In addition, we will discuss the advantage of the technique for the imaging spectrograph data like the NST FISS.

• Geomechanics and Engineering
• /
• 제35권5호
• /
• pp.475-486
• /
• 2023

Ballast particles have an irregular shape and are discrete in nature. Due to the discrete nature of ballast, it exhibits complex mechanical behaviour under loading conditions. The discrete element method (DEM) can model the behaviour of discrete particles under a multitude of loading conditions. DEM is used in this paper to simulate a series of three-dimensional direct shear tests in order to investigate the shear behaviour of railway ballast and its interaction at the microscopic level. Particle flow code in three dimension (PFC3D) models the irregular shape of ballast particles as clump particles. To investigate the influence of particle size distribution (PSD), real PSD of Indian railway ballast specification IRS:GE:1:2004, China high-speed rail (HSR) and French rail specifications are generated. PFC3D built-in linear contact model is used to simulate the interaction of ballast particles under various normal stresses, shearing rate and shear box sizes. The results indicate how shear resistance and volumetric changes in ballast assembly are affected by normal stress, shearing rate, PSD and shear box size. In addition to macroscopic behaviour, DEM represents the microscopic behaviour of ballast particles in the form of particle displacement at different stages of the shearing process.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제4권4호
• /
• pp.307-311
• /
• 2004

This paper presents an efficient architecture that optimizes the design of SEED S-box using composite field arithmetic. SEED is the Korean standard 128-bit block cipher algorithm developed by Korea Information Security Agency. The nonlinear function S-box is the most costly operation in terms. of size and power consumption, taking up more than 30% of the entire SEED circuit. Therefore the S-box design can become a crucial factor when implemented in systems where resources are limited such as smart cards. In this paper, we transform elements in $GF(2^8)$ to composite field $GF(((2^2)^2)^2)$ where more efficient computations can be implemented and transform the computed result back to $GF(2^8)$. This technique reduces the S-box portion to 15% and the entire SEED algorithm can be implemented at 8,700 gates using Samsung smart card CMOS technology.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.319-322
• /
• 2002

In this paper, an experimental study is carried out to find out structural behavior of upper slab in concrete box girder bridges. The major variables in the tests are the cross-section of upper slab including haunch dimensions. The strains of concrete and steel bars and the deflections of slabs are measured automatically during the tests. The test results indicate that the size of haunches has much influence on the structural behavior of box girders. The appropriate haunch dimensions are suggested from the present study.

• 한국IT서비스학회지
• /
• 제11권2호
• /
• pp.275-289
• /
• 2012

Although the specification of packaging box is one of the most important process to be considered before deciding cost in terms of production and logistics, there are no efficient services in our country at this time as such the making decision only through the empirical knowledge. In this research, we have developed the packaging specification design system based on the web online packaging IT service. The developed system was advanced from the existing-inefficient process of deciding the specification of packaging box, and which can decide the specification of packaging box considering the efficiency of logistics through use of IT based tool. Therefore, this study shows applied cases of normalized packaging process through the obtained packaging design simulation program. The packaging specification design system can provide the simulation and user interface. Those could calculate the specification of packaging box(packaging box size, packaging box quantity, packaging box pattern, packaging compressive strength, packaging cost etc.) considering the efficiency of logistics.