배수설비 시스템에서 PVC 관의 소음 특성

안창환,공성훈 한국생활환경학회 2007 한국생활환경학회지 Vol.14 No.3

The purpose of this study is to suggest the fundamental data for noise control design and standard criteria for PVC pipe by theoretical simulation and experimental research. To predict decibel noise pressure, the actual and theoretical test results by using PVC single pipe, PVC double pipe and PVC threefold-jointed, are carefully examined for the drainage facilities' nise in this study. Also, this study would presents fundamental informations and date on the reduction of the drainage facilities' noise by analyzing vibration modes of pipes. The major results are as follows; 1) The noise protect performance of double PVC pipe are prefer then single PVC pipe 10 dB condition. 2) Theoretical noise reduction effects for double PVC pope and threefold-jointed pipe are have similar effects in 2 KHz~4 KHz band and some differences are shown in low level Hz band.

Calcium homeostasis in diabetes mellitus

안창환,강지훈,정의배 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.3

Diabetes mellitus (DM) is becoming a lifestyle-related pandemic disease. Diabetic patients frequently develop electrolyte disorders, especially diabetic ketoacidosis or nonketotic hyperglycemic hyperosmolar syndrome. Such patients show characteristic potassium, magnesium, phosphate, and calcium depletion. In this review, we discuss a homeostatic mechanism that links calcium and DM. We also provide a synthesis of the evidence in favor or against this linking mechanism by presenting recent clinical indications, mainly from veterinary research. There are consistent results supporting the use of calcium and vitamin D supplementation to reduce the risk of DM. Clinical trials support a marginal reduction in circulating lipids, and some meta-analyses support an increase in insulin sensitivity, following vitamin D supplementation. This review provides an overview of the calcium and vitamin D disturbances occurring in DM and describes the underlying mechanisms. Such elucidation will help indicate potential pathophysiology-based precautionary and therapeutic approaches and contribute to lowering the incidence of DM.

엔트로피에 의한 수평급수관로 해석에 관한 연구

안창환,공성훈 대한건축학회 1999 대한건축학회논문집 Vol.15 No.3

Water is very useful to human life, and the importance of water supply system has been increased due to the environmental pollution This study defines the entropy as one of variable water flow rates on the horizontal water supply piping system in oiler to provide the satisfactory water supply system. Furthermore, in this study, theoretical interpretation and an experiment were carried out in order to calculate the optimum water pressure and diameter. A horizontal supply water piping system was equipped at the inside of a laboratory for the with a laboratory for the purpose of this experiment. Water flow rates, pressure, and velocity were measured with respect to the operation of faucets. From the measured data, the qualitative variation of entropy m the horizontal supply water piping system was analyzed and also it was suggested to the basic data for the optimum design of water piping system

초고압 전력기기의 부분방전 인공지능 인식 알고리즘 적용 연구

안창환 한국조명.전기설비학회 2019 조명·전기설비학회논문지 Vol.33 No.4

In this study, a study was conducted to improve the defect recognition rate by converting the PRPS Raw-Data acquired in the event of partial discharge of high voltage power equipment into PRPD type and using the extracted parameter as input data of artificial intelligence algorithm. As a result, it was confirmed that sufficient recognition rate was obtained to accurately recognize the type of defect compared to the conventional partial discharge recognition method using the input image. Since it is much more advantageous in terms of computational speed than image recognition method, it is reasonable to use artificial intelligence algorithm method using parameter as a way to process vast signals generated in the field. There is no authorized regulation on the recognition rate of partial discharge measurements. The only recognition rate presented by the Korea Electric Power Corporation purchase specification is 90%. Considering this, the recognition rate obtained in this study is more than 99%, which shows that the learning speed and recognition rate are improved compared to the existing method.

Design of T-S Fuzzy Model based Adaptive Fuzzy Observer and Controller

안창환 한국조명.전기설비학회 2009 조명·전기설비학회논문지 Vol.23 No.11

This paper proposes the alternative observer and controller design scheme based on T-S fuzzy model. Nonlinear systems are represented by fuzzy models since fuzzy logic systems are universal approximators. In order to estimate the unmeasurable states of a given unknown nonlinear system, T-S fuzzy modeling method is applied to get the dynamics of an observation system. T-S fuzzy system uses the linear combination of the input state variables and the modeling applications of them to various kinds of nonlinear systems can be found. The proposed indirect adaptive fuzzy observer based on T-S fuzzy model can cope with not only unknown states but also unknown parameters. The proposed controller is based on a simple output feedback method. Therefore, it solves the singularity problem, without any additional algorithm, which occurs in the inverse dynamics based on the feedback linearization method. The adaptive fuzzy scheme estimates the parameters and the feedback gain comprising the fuzzy model representing the observation system. In the process of deriving adaptive law, the Lyapunov theory and Lipchitz condition are used. To show the performance of the proposed observer and controller, they are applied to an inverted pendulum on a cart.

아파트에서 적정 급수량 산정을 위한 사용수량에 관한 조사 연구

안창환,ChangHuanAn 한국주거학회 1994 한국주거학회 논문집 Vol.5 No.1

Using water in each apartment is influnced by several facters including the income level of inhabitants, the manner of life, the area apartments and climate. The automization of santory machines or facilites in recently bulit apartements has caused largely increases in amount of water use. Therefore the design for water supply is very important for the maintenance of the optimum level or pressure of water supply. This study is based on the offer of basic data for improving the quality of water supply and imploying the sanitory machine or sanitory facilites by analysis of amount increased of water use rapidly. The quantity of hot and cold water use by year is examined as a factor of construction in apartment.

배관재에 따른 표면결로 해석에 관한 연구

안창환,공성훈 한국생활환경학회 2007 한국생활환경학회지 Vol.14 No.3

The purpose of this study is to present fundamental data on insulation design for appropriate pipes through interpretation of condensation, comparison and appraisal of experimental analysis. To establish heat transfer, vapour permeability process and evaluate condensation on piping materials, in this study, we measured environmental elements such as dry-bulb temperature, relative humidity through an experiment for PVC pipe material and evaluated the characteristic of heat transfer and vapor permeability in two pipe material (PVC single one pipe, PVC double pipe), made of same material, from the analyzed results of the experiment. Response factor method was used for theoretical interpretation and we examined it with the outcome from the test to estimate whether or not condensation occurred. The major results are the performance of surface condensation protector and insulation rate of heat flux are more prefer to PVC double pipe than PVC single pipe.

π-공액계 분자의 삼중항 여기 상태에 대한 Density Functional Theory (DFT)에 기반한 계산 방법들의 비교: 시간-의존 DFT (TD-DFT), Tamm-Dancoff 근사법을 적용한 DFT (TDA-DFT), 스핀-비제한 DFT (UDFT)

안창환,김동욱 대한화학회 2019 대한화학회지 Vol.63 No.2

We compared methodologies based on the density functional theory (DFT), e.g., time-dependent DFT (TD-DFT), TD-DFT within Tamm-Dancoff approximation (TDA-DFT), and spin-unrestricted DFT (UDFT), that are usually employed to optimize the geometries of π-conjugated molecules in their lowest lying triplet excited (T1) state. As a model system for π-conjugated molecules, we employed 1,2,3,4,5-pentacyano-6-phenyl-benzene. In conjunction with 6-31G(d) basis sets, we made use of gap-tuned range-separated ωB97X functional which is often employed recently in the calculations of molecular excited states. Near the equilibrium geometries, we found that the important difference between the geometries derived at UDFT level and those at TD-DFT or TDA-DFT methods: more stable ground-state energies but higher triplet excitation energies for UDFT derived geometries. In the studies, we discuss such differences in more detail. π-공액계 분자에 대해, density functional theory (DFT) 방법에 기반한 일반적인 삼중항 구조 최적화 방법들, 즉, 시간 의 존적 DFT (TD-DFT), Tamm-Dancoff 근사법에 기반한 TD-DFT (TDA-DFT), 그리고 스핀-비제한 DFT (UDFT)에 대한 점검을 수 행하였다. 모델 분자로서 1,2,3,4,5-pentacyano-6-phenyl-benzene가 이용되었고, 6-31G(d) 기저 함수와 더불어 여기 상태 계산에 최 근 자주 사용되는 에너지 차 조정 영역 분리 functional인 ωB97X functional이 사용되었다. 계산 결과 평형 구조 근처에서, UDFT 최적화된 구조는 TD-DFT 및 TDA-DFT 계산 구조와는 다른 차이점을 보인다. 즉, 보다 안정한 바닥 상태 에너지와 보다 높은 삼 중항 여기 에너지가 UDFT 최적화 구조에서 보인다. 본 논문에서는 이러한 차이에 대해 보다 자세히 토의된다.

직류전원시스템에서 발생하는 아크사고 검출기법에 대한 연구

안창환 대한전자공학회 2022 전자공학회논문지 Vol.59 No.4

본 논문은 직류전원시스템에서 발생하는 아크사고를 검출하는 기법을 제안하고 이에 대한 실증 실험을 수행하였다. 기존의 아크사고 검출법은 퓨리에변환을 통하여 주파수영역에서 전력스펙트럼 밀도를 이용하여 분석하는 방법이 주로 사용 되지만 신뢰성이 낮은 문제가 있다. 아크사고 검출률을 향상시키기 위한 방법으로 아크사고에 적합한 주파수 대역과 아크사고 선정에 필요한 기준치를 전력스펙트럼 밀도의 평균값을 선정한다. 아크사고에 적합한 주파수 대역은 10kHz~100kHz이며, 보정법을 이용하여 핑크노이즈를 제거하여 전력스펙트럼 밀도의 평균값을 구한다. 마지막으로 아크사고 검출의 신뢰성을 증가시키기 위해서 주파수 대역에서 특정 주파수 구간을 나눠 구간별 전력스펙트럼밀도의 평균값을 이용하는 주파수분할법을 제안하였다. 주파수분할법에 대한 검출률을 확인하기 위해서 모의 직류아크사고 실험계를 구성하였다. 실험 결과 주파수 분할법을 이용한 아크사고 검출률이 전력스펙트럼밀도를 이용한 아크사고 검출률보다 약 40% 이상 높게 나타났다. 주파수분할법을 이용한 아크사고 검출방법은 태양광발전소를 포함한 직류전원시스템에 활용될 것으로 예상된다.

엔트로피에 의한 수직급수관로 해석에 관한 연구

안창환,공성훈 대한건축학회 1999 대한건축학회논문집 Vol.15 No.6

The water supply system supplies very necessary water to human Iife. The reason is that recently the importance of water supply system has increased due to environmental pollution. This thesis interpreters entropy as water flow to supply water pipes for maintenance of optimal supply to the water environment. Furthermore, in this study, theoretical interpretation and an experiment were carried out in order to calculate the optimum water pressure and diameter. A vertical supply water piping system was equipped at the inside of a laboratory for the with a laboratory far the purpose of this experiment Water flow rates, pressure, and velocity were measured with respect to the operation of faucets. From the measured data, the qualitative variation of entropy in the vertical supply water piping system was analyzed and also it was suggested to the basic data for the optimum design of water piping system.