• 한국응용과학기술학회지
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• 제28권1호
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• pp.6-9
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• 2011

Step feed process was analyzed stoichiometrically for the optimal operation conditions in this study. In case of optimal operation conditions, minimum R (sludge recycling) value, r (internal recycling ratio) value, and n (influent allocation ratio) value for the step feed process to acquire the maximum TN removal efficiency were identified by theoretical analysis. Maximum TN removal efficiency, based on stoichiometric reaction, can be obtained by controlling n value for the step feed process.

• 한국정밀공학회지
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• 제6권3호
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• pp.24-31
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• 1989

By use of the machining center, step-feed drilling was operated under the variety of conditions as to materials, tools and cutting conditions. Based on this study the following conclusions can be drawn : 1) The cutting force can be diminished by utilizing the step-feed working; specially the most effective was it for the brass among the carbon steel, the brass, and the cast iron. 2) Tool life can be enlarged more than double when three-step-feed working is used. 3) For the constant cutting-depth(30mm), the most optimal number of stepping is 3.

• 한국정밀공학회지
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• 제13권12호
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• pp.46-53
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• 1996

Micro drilling is one of the most important machining types and its necessity becomes more and more increasing in the whole field of industry. Micro drilling, however, has few the case of practical application, because it requests high techniques : manufacturing micro drill, treating chip, producting precise hole shape and progressing machining effeciency. Micro drilling has a technical problem: drill breakage from the lack of drill rigdity and the interuption of chip. It is, therefore, essential to select the proper cutting conditions and the step fed for the method solving the lack of rigidity and the interruption of chip. Especially, step feed is very efficient to avoid the breakage of drill, but bring about reducing of cutting efficiency. The study on step feed must be requested more than the present in the near future. The purpose of this paper is to investigate experimentally about cutting conditions which affect on tools and round errors and to estimate about the effect of step feed as well as optimal step feed size to solve the breakage of drill.

• 한국가금학회지
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• 제21권4호
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• pp.257-266
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• 1994

Three protein feeding systems for egg-type pullets involving conventional step-down protein 18-15-12%), step-up protein(12-15-18%) and single-stage low protein (13-13-13%) with an iso-energy level of 2,900 ME kcal /kg were compared to examine the effect on pullet growth and subsequent laying performance. During the growing period, pullets subjected to the step-up and single-stage low protein feeding systems were lighter in body weight and consumed less feed and netabolizable energy than those on the conventional step-down protein feeding system(P<0.05). 3ut the pullets on the step-up protein diet consumed more protein, and those on the single-stage low protein diet consumed less protein than those on the step-down protein diet(P<0.05). Also, he feed cost was less in pullets on the single-stage low protein diet than in those on the other systems(P<0.05). During the laying period, sexual maturity was later in hens reared on the step-up and single-stage low protein diets than in those on the step-down protein diet(P<0.05), however, average hen-day egg production and egg weight were not significantly affected by the protein feeding systems in the growing period. Daily feed intake and feed required per egg were significantly reduced in hens on the single-stage low protein diet compared to those on conventional protein feeding system(P<0.05). It was concluded that the 13% single-stage low protein feeding system produced smaller pullets with less feed, energy, protein, and feed cost during the growing period, and hens reared on that system consumed less feed during the laying period without any impairment of production compared to the conventional rearing system.

• 한국응용과학기술학회지
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• 제22권1호
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• pp.62-70
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• 2005

Step-feed process for biological nitrogen removal were analyzed numerically for the each unit and final total nitrogen(TN) effluent by water quality management(WQM) model and the results were compared data from these wastewater treatment plants. No bugs and logic error were occurred during simulation work. All of the simulation results tried to two times were obtained and both results were almost same as this model has become good reappearance. It was concluded that most of nitrogen removal occurred in the first oxic tank. Thus the controlling of the first anoxic tank may be more important in term of nitrogen removal. Also each unit of simulation result was kept good relationship with that of measured data. Accordingly this WQM model has good reliance. Finally, WQM model can predict final TN effluent within ${\pm}6.0mg/{\ell}$.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.66-69
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristicsof a presented load current feed -forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• 한국산학기술학회논문지
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• 제11권2호
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• pp.675-680
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• 2010

본 연구에서는 저농도로 유입되어 정상적인 운영이 되지 않고, 질소제거가 어려운 소규모 하수처리시설의 문제점을 해결하기 위하여 5Stage로 구성된 하수고도처리 공정의 저농도 유입성상에서 최적의 단계유입비와 내부순환비를 결정하기 위해 Lab-Scale 모형실험장치를 제작하여 실험하였다. 저농도의 유입조건에서 효율적인 고도처리를 위해 내부순환과 단계유입이 공정성능에 미치는 영향을 평가한 결과는 다음과 같다. 첫째, 분석항목별 처리효율은 BOD 90.0%, COD 87.8%, T-N 71.0%, T-P 75.3%로 나타났으며, T-N은 단계유입에 따라 처리효율의 변동이 있는 것으로 나타났다. 둘째, 혐기조로 유입되는 단계유입비 70, 60, 50%에서는 각각 73, 80, 78%로 나타나 최적의 단계 유입비 범위로 판단되었다. 셋째, 질소제거를 위해 내부순환을 할 경우 내부순환을 하지않는 경우보다 질소 제거효율이 증가됨을 알 수 있었고, 내부순환비가 150%이상에서는 더 이상 처리효율에 영향을 미치지 못하는 것으로 나타났다. 이는 다량의 순환으로 인해 무산소조에 DO의 유입으로 인한 것으로 판단된다. 따라서 내부순환비는 50~150%가 적정한 것으로 판단되었다.

• 정보보호학회논문지
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• 제19권5호
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• pp.143-149
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• 2009

본 논문에서는 SHA-3의 1 라운드 후보로 제안된 알고리즘인 ARIRANG의 단계수가 축소된 버전들에 대한 역상 공격을 소개한다. 이 공격은 단계 1부터 단계 33까지의 ARIRANG-256 및 ARIRANG-512의 33단계 OFF(Original FeedForward1) 버전의 역상을 찾아내며, 단계 1부터 단계 34까지의 ARIRANG-256 및 ARIRANG-512의 31단계 MFF(Middle Feed-Forward1) 버전의 역상을 찾아낸다. 공격 복잡도는 ARIRANG-256에 대해서 약 $2^{241}$이고 ARIRANG-512에 대해서 약 $2^{481}$이다.

• 한국가금학회지
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• 제49권4호
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• pp.273-279
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• 2022

The objective of this study was to evaluate an in vitro procedure to estimate the crude protein (CP) digestibility of feed ingredients and mixed diets in broiler chickens. The apparent ileal digestibility (AID) of the CP was measured using 23-d-old male broilers. Three experimental diets, containing three feed ingredients, namely soybean meal (SBM), canola meal (CM), and corn distiller's dried grains with solubles (DDGS), were used as the sole source of CP. A 2-step in vitro procedure was used to estimate in vivo CP digestibility; all the experiments were performed in triplicate. In step 1, the feed ingredient and mixed diet samples were incubated for 4 h at 40 °C with a pH 2.0 pepsin solution, and in step 2, the flasks were incubated for 12 h at 40 °C with a pH 6.8 pancreatin solution. Following incubation, all the samples were filtered; the undigested residues were collected and pooled together to analyze the undigested CP concentration. The in vitro CP digestibility of mixed diets and feed ingredients were 93.2% and 93.0% for SBM, 86.8% and 86.7% for CM, and 83.8% and 79.1% for DDGS, respectively. The coefficients of determination (R2) between the CP digestibility values for the feed ingredients and the in vitro CP digestibility values for the feed ingredients or respective mixed diets were 0.87 or 0.67. The results of the study demonstrated that the in vitro CP digestibility values obtained from the respective mixed diets were better estimates than the values obtained from the individual feed ingredients to predict the AID of CP in feed ingredients fed to broiler chickens.

• 한국생산제조학회지
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• 제8권1호
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• pp.81-88
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• 1999

This paper was carried out to know the influence of advanced austempered ductile cast iron (ADI) on the tool life and mechanical properties of drilling machinability. For manufactured method of ADI, the spheroidal graphite cast iron were austenized at 90$0^{\circ}C$ for 1 hour and then austempered for 2 hour at 37$0^{\circ}C$ in the salt bath. And interrelationship has been investigated between tool life and mechanical characteristics of specimen material on drilling condition when the ordinary and step-feed drilling are carried out to drill holes of specimens. Tensile strength and hardness of ADI decrease and elongation of ADI increases with the increase austempered temperature. It is known that about 2 times of tool life in the case of step-feed decreases compared with ordinary feed due to the high hardness of ADI and hardness ascribed to the fact that retained austenite became to martensite state due to cutting heat in drilling. Under the constant feed rate 0.1mm/rev relation between hardness and length of end tip after drilling can be formularized to Hv=$788.46L^{-0.096}$ for the cutting speed 6.1m/min.