• 디지털융복합연구
• /
• 제17권11호
• /
• pp.207-213
• /
• 2019

대부분의 차량에 적용되어 있는 연료차단(fuel-cut) 관성주행은 변속기어 체결 상태에서 가속페달을 방치할 때 자동으로 작동하게 된다. 이 때 연료분사가 일시적으로 중단되므로 연비 향상 효과가 상당하다. 본 연구에서는 GPS를 이용하여 측정된 차속, 가속도, 도로구배 등의 신호를 바탕으로 하는 연료차단 관성주행 감지법을 제안하였다. 관성 주행시 작용하는 주행저항력에 의해 계산되는 가속도값과 GPS에서 실시간으로 측정되는 가속도값을 비교하는 방식이다. 실도로 주행 데이터를 측정하여 이 감지법을 평가한 결과 약 80% 수준의 정확도를 얻을 수 있었다. 도로구배가 다소 큰 12km 정도의 국도를 16분 동안 주행하면서 측정한 약 9,600개의 속도, 가속도, 도로구배 및 연료소모량 데이터에 감지법을 적용하여 얻은 결과이다. 인젝터 분사파형 분석을 위한 배선작업 등이 불필요하여 간단하게 연료차단여부를 판정할 수 있는 장점이 있다. 다만, 속도, 가속도 및 도로구배의 변화율이 연료소모량의 변화율에 비해 훨씬 크게 나타나기 때문에 감지법의 오차도 다소 증가하는 것을 알 수 있었다.

• 한국산학기술학회논문지
• /
• 제13권2호
• /
• pp.801-807
• /
• 2012

본 논문에서는 LC 필터 기술을 기반으로 하는 주파수 단일 하향 변환기를 설계 및 제작하였다. 설계한 단일 하향 변환기는 저잡음 증폭기, 혼합기 IF 증폭기, LC 필터로 구성하였으며 DC block 커패시터와 RF bypass 커패시터로 구성된다. 설계한 변환기는 IC를 LC 필터로 대치하여 전력을 감소시키고 제작비용을 낮추어주는 효과를 보인다. 본 논문에서 설계, 제작한 단일 하향 변환기는 이득이 약 10dBm이고 70MHz에서 18MHz의 대역폭을 실현하였다.

• 한국가구학회지
• /
• 제27권2호
• /
• pp.145-153
• /
• 2016

Today, furniture design, which is changing and diversified, a movement to search a new formative world while reviving our traditionality is continuously proceeded, that implies a new possibility in our culture. In respect of such diversified materials, Korean traditional paper, Hanji (韓紙), has already been acknowledged with its excellence. Also, Hanji is a material that fully contains aesthetic consciousness of Korean people, accordingly, this research investigated and analyzed mainly with Sarangbang furniture among Joseon antique furniture, in order to study the possibility of Hanji decorated furniture as the objet in our interior space. This research utilized Paper cut technique (剪紙技法) among Hanji Crafts technique of expressive elements of Sarangbang furniture using Hanji, which is to make patterns and attach them by cutting out or engraving colored papers using scissors or graver to the wooden frame (白骨). Through this, this research could investigate production process utilizing Paper cut technique, also, Sarangbang furniture utilizing such Paper cut could be settled down as the objet with functional aspect and aesthetic completion in our interior space. Also, the researcher presents value of our original furniture by suggesting final output and considers that systematic researches should be conducted continuously on furniture henceforth utilizing Paper cut technique.

• 한국기계가공학회지
• /
• 제15권2호
• /
• pp.111-117
• /
• 2016

The cutting performance of a developed small-angle spindle tool was investigated with Al6061 using a TiAlN coated high-speed steel end mill. Up-cut and down-cut processes in a milling machine were carried out at the range of 1000-4000 rpm for spindle speed and 50-300 mm/min for feed rate. As a result, the highest cutting force in the Fx direction was obtained from the up-cut process when the spindle speed was 1000 rpm and the feed rate was 100 mm/min. In the Fy direction, the highest cutting force appeared in the up-cut process at a feed rate of 250 mm/min at the same spindle speed. Conversely, the lowest cutting force came out in the up-cut process at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. As for surface finish, the finest surface roughness was obtained as Ra 0.7642 um at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. Consequently, given the cutting performance of the developed small-angle spindle tool, we conclude that its use in industrial practice is feasible.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.629-634
• /
• 2004

When it was a localized torrential downpour last year, a natural-slope fell down above a cut-slope. They were caused that stress was opened by cutting slope, ground water level rose quickly and a ground mass strength fell etc. So volume of ground mass increase because of that reasons, finally the disturbed ground was collapse. Therefore I suggest that safety of a natural-slope is a consideration, when a cut-slope is made by cutting ground.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2008년도 추계학술대회 논문집
• /
• pp.10-13
• /
• 2008

Fuel cell systems have witnessed remarkable development in recent years as they offer a clean and efficient alternative for power generation. Testing was conducted to determine the safety performance of a residential fuel cell system when subjected to abnormal operation condition, especially for voltage sag and fuel cut. In case of voltage sag to 198V, its arriving time at rated power had shown a slight lag but there wasn't any noticeable change when operating it between rated voltage(220V) and 10% voltage sag(198V). In case of fuel cut, it also showed stable shut-down characteristics. The test results are being used to develop a new safety evaluation for residential fuel cell system.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권4호
• /
• pp.358-364
• /
• 1999

The auxiliary transformers or start-up/stand-by transformer(s) are installed against the start-up and shut-down of generator and emergency status in fossil power plant. The on-site power supply configuration using these transformers must be determined, considering configuration requirements, site characteristics, reliability and availability severely because it is remarkably important for safety and ecfonomy of plant. The auxiliary or start-up/stand-by power supply configuration has been determined considering only safety requirements and construction cost until now in Korea. This paper presents general theorems for the reliability estimation and proposes 2-unit based 4 alternatives for the start-up power supply stystem of 500㎿ standardized fossil power plant. The reliability and unavailability of equipment, system and configuration are determined using minimal cut-set methodology. The optimized plan of 4 alternatives is determined based on this ultimate reliability and unavailability.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.409-414
• /
• 2009

The SK Chemical R&D center is an eco-friendly building designed as top score in the GBCC(GREEN BUILDING CERTIFICATE CRITERIA). This building has applied various eco-friendly technologies such as energy /water resource cutdown, improvement of indoor quality and improvement of user convenience, etc through eco-friendly concept from the design phase. In this thesis, an economic efficiency evaluation has been performed on building energy cwater resource cutdown technologies among them and the results are as follows. The building energy has cut down about 40% compared to ordinary buildings and the investment recovery period was shown as about 5 years. The water resource has cut down about 63% compared to ordinary buildings and the investment recovery period was shown as about 10 years.

• KIEAE Journal
• /
• 제13권2호
• /
• pp.39-46
• /
• 2013

Recently, the field of construction is putting a variety of effort into reducing CO2, since global warming is being accelerated due to climate changes and the increase of greenhouse gas. For reduction of CO2 in the field of construction, it is required to make plans to cut down heating energy of buildings and especially, it is urgently needed to cut down energy of residential buildings in rural area where occupies the majority of consumption of petroleum-based energy sources. Therefore, this research compared and analyzed the actual energy consumption, by evaluating energy performance of a detached house applying passive house design components for reduction of energy. As the result, energy consumption showed remarkable differences, according to the operation of a heat recovery ventilation unit which is one of passive house design components, and building energy consumption displayed remarkable differences, too, depending on the difference of airtightness performance during building energy simulation conducted in process of design. Based on these results, the importance of airtightness performance of passive house was verified. The result of the actual measurement of energy consumption demonstrated that LNG was most economical amongst several heat resources yielded, on the basis of LPG source energy consumption measured within a certain period of time, and it was followed by kerosene. LPG was analyzed to have a low economic efficiency, when used for heating.

• 센서학회지
• /
• 제29권5호
• /
• pp.324-327
• /
• 2020

The impact of output conductance (g_o) on the short-circuit current-gain cut-off frequency (f_T) in In_0.8Ga_0.2As high-electron-mobility transistors (HEMTs) on an InP substrate was investigated. An attempted was made to extract the values of f_T in a simplified small-signal model (SSM) of the HEMTs, derive an analytical formula for f_T in terms of the extrinsic model parameters of the simplified SSM, which are related to the intrinsic model parameters of a general SSM, and verify its validity for devices with L_g from 260 to 25 nm. In long-channel devices, the effect of the intrinsic output conductance (g_oi) on f_T was negligible. This was because, from the simplified SSM perspective, three model parameters, such as g_{m_ext}, C_{gs_ext} and C_{gd_ext}, were weakly dependent on g_oi. However, in short-channel devices, g_oi was found to play a significant role in degrading f_T as L_g was scaled down. The increase in g_oi in short-channel devices caused a considerable reduction in g_{m_ext} and an overall increase in the total extrinsic gate capacitance, yielding a decrease in f_T with g_oi. Finally, the results were used to infer how f_T is influenced by g_oi in HEMTs, emphasizing that improving electrostatic integrity is also critical importance to benefit fully from scaling down L_g.