• 한국물환경학회지
• /
• 제29권1호
• /
• pp.55-65
• /
• 2013

It is very difficult to apply stream flow data directly to the management of Total Maximum Daily Loads because there are some differences between the unit watershed and the stream flow monitoring network in their characteristics such as monitoring locations and its intervals. Flow duration curve can be developed by linking the daily flow data of stream monitoring network to 8 day interval flow data of the unit watershed. This study investigated the current operating conditions of the stream flow monitoring network and the flow relationships between the unit watershed and the stream flow monitoring network. Criteria such as missing and zero value data, and correlation coefficients were applied to select the stream flow reference sites. The reference sites were selected in 112 areas out of 142 unit watersheds in 4 river basins, where the stream flow observations were carried out in relatively normal operating conditions. These reference sites could be utilized in various ways such as flow variation analysis, flow duration curve development and so on for the management of Total Maximum Daily Loads.

• Journal of Chest Surgery
• /
• 제35권5호
• /
• pp.375-380
• /
• 2002

배경: 개심술후 발생하는 흉골감염은 심각한 합병증일 뿐만 아니라 술후 사망률을 높이는 한 요인이 된다. 저자들은 1999년 7월 집중치료실 및 수술장 이전을 계기로 이를 전후로한 환자들의 흉골감염 발생현황을 비교 분석함으로써 집중치료실 및 수술장 개선이 흉골감염에 미치는 영향을 알고자 하였다. 대상 및 방법: 집중치료실 및 수술장 이전 시점을 전후로 하여 1997년 1월 1일부터 1998년 12월 31일까지 개심술을 시행받은 환자 237명을 Group I으로, 2000년 1월 1일부터 2001년 7월 31일까지 개심술을 시행받은 환자 216명을 Group II로 분류하여 총 453명을 대상으로 하였다. 만 15세 이상의 성인 환자에서 정중흉골절개술 및 심폐바이패스를 시행한 경우만을 포함하였고 흉골감염 이외의 원인으로 사망한 예는 포함하지 않았다. 결과: 흉골감염은 GroupI에서 18례(8.0%), Group II에서 1례(0.49%) 발생하였다. 흉골감염에 영향을 미치는 것으로 알려진 위험인자 중에서 응급수술여부, 심폐바이패스시간, 수술시간, 수혈량, 기관절개술유무, 재수술여부 등이 유의한 연관성이 있었으며, 이들을 대상으로 시행한 로지스틱 회귀분석에서 집중치료실과 수술장의 이전이 흉골감염에 유의한 영향을 미치는 것으로 나타났다.(p=0.029, 95% 신뢰구간 0.011∼0.788). 결론: 개심술후 흉골감염에 영향을 주는 여러 인자들이 알려져 있지만 집중치료실 및 수술장의 개선이 흉골감염의 발생을 줄일 수 있는 하나의 방법으로 생각된다.

• 설비공학논문집
• /
• 제20권4호
• /
• pp.245-251
• /
• 2008

The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the operating characteristics and performance of a simultaneous heating and cooling heat pump in the heating-main operating mode were investigated experimentally. The system adopted a variable speed compressor with four indoor units and one outdoor unit with R-410A. In the heating-main mode, the cooling capacity was lower than the design cooling capacity due to the reduction of the flow rate in the indoor unit for the cooling, with the increase of the heating capacity. To solve these problems, the performance characteristics of the simultaneous heating and cooling heat pump in the heating-main mode were investigated by varying the flow rate to the indoor unit for the cooling and the compressor rotating speed. In addition, the adequate control methods were suggested to improve the system efficiency.

• 항공우주시스템공학회지
• /
• 제12권5호
• /
• pp.48-53
• /
• 2018

본 논문에서는 RTOS과 항공기의 3차원 충돌회피 알고리즘을 세 개의 MCU에 적용하여 각 MCU의 성능을 비교하였다. MCU는 많이 사용되는 Microchip Technology사의 ATmega2560과 STM사의 ARM Cortex-M3, ARM Cortex-M4를 선정하였으며, RTOS는 공개되어 있는 FreeRTOS 를 사용하였다. 성능을 확인하기 위해 적용된 3차원 충돌회피 알고리즘은 수직회피와 수평회피를 통합한 알고리즘이며 C++로 구현하였다. MCU의 성능은 각 MCU의 사용 메모리와 계산 시간을 측정하여 비교하였다. 비교 결과 세 MCU 중, 계산 시간은 ARM Cortex-M4가 빨랐으며, ATmega2560이 적은 메모리를 사용하였다.

• 산업경영시스템학회지
• /
• 제38권1호
• /
• pp.21-29
• /
• 2015

A steady-state controllable M/G/1 queueing model operating under the {T:Min(T,N)} policy is considered where the {T:Min(T,N)} policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or after T time units elapsed without a customer' arrival, the time instant when Nth customer arrives at the system or T time units elapsed with at least one customer arrives at the system whichever comes first. After deriving the necessary system characteristics including the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time for the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, procedures to determine the optimal values of the decision variables included in the operating policy are provided based on minimizing the total expected cost function per unit time to operate the queueing system under considerations.

• 산업경영시스템학회지
• /
• 제37권1호
• /
• pp.96-103
• /
• 2014

A steady-state controllable M/G/1 queueing model operating under the (TN) policy is considered where the (TN) policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or the time instant when Nth customer arrives at the system after T time units elapsed without customers' arrivals during that time period. After deriving the necessary system characteristics such as the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time in the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, the optimal values of the decision variables included in the operating policies are determined by minimizing the total expected cost function per unit time to operate the system under consideration.

• 한국압력기기공학회 논문집
• /
• 제7권4호
• /
• pp.57-62
• /
• 2011

As NPPs' operating times increase, the integrity of nuclear components is continually degraded due to aging effects of systems, structures and components. In addition, for the case of continued operation beyond design life, additional aging effects occurred during the extended operating period lead to more degradation of the integrity of nuclear components. Therefore, it is very important to mange and evaluate the aging to secure the safety of NPPs. Wolsong unit 1 is approaching to its design life of 30 years in 2012. The license renewal documents for continued operation of Wolsong unit 1 Is under reviewing now. In this paper, regulatory technologies for continued operation of Wolsong unit 1 developed by KINS will be introduced. That technologies include the safety review guidelines, regulatory guides for aging management program and regulatory program for audit calculation.

• 한국압력기기공학회 논문집
• /
• 제6권1호
• /
• pp.43-49
• /
• 2010

The piping failure probability of the reactor coolant system in Kori unit 1 was evaluated considering stress corrosion cracking. The P-PIE program (Probabilistic Piping Integrity Evaluation Program) developed in this study was used in the analysis. The effect of some variables such as oxygen concentration during start up and steady state operation, and operating temperature, which are related with stress corrosion cracking, on the piping failure probabilities was investigated. The effects of leak detection capability, the size of big leak, piping loops, and reactor types on the piping failure probability were also investigated. The results show that (1) LOCA (loss of coolant accident) probability of Kori unit 1 is extremely low, (2) leak probability is sensitive to oxygen concentration during steady state operation and operating temperature, while not sensitive to the oxygen concentration during start up, and (3) the piping thickness and operating temperature play important roles in the leak probabilities of the cold leg in 4 reactor types having same inner diameter.

• 해양환경안전학회지
• /
• 제20권4호
• /
• pp.398-404
• /
• 2014

우리나라 주요 항만에 규정되어 있는 정박지와 관련한 운영 세칙은 항만마다 정박지 운영 기준이나 정박지 선박수용능력에 대한 단위가 단일화 되어있지 않으며, 동일한 사안에 대해 다른 용어들을 사용하고 있다. 이로 인해 정박지를 운영하거나 이용하고자 하는 당사자들에게 큰 혼란을 주고 있는 상황이다. 본 연구에서는 국내 주요 항만의 정박지 운영 세칙을 검토하여 세칙명, 단위 및 용어의 단일화 방안을 제안하였다. 아울러 정박지 운영상의 혼란을 최소화하기 위하여 외국 주요 항만의 정박지 현황 검토를 통하여 향후 세칙 개정시 정박지 명칭 부여 원칙, 정박지 선박수용능력 단위 및 정박지의 수용가능한 선박 척수의 설정이 이루어지도록 제안하였다.

• 전기의세계
• /
• 제29권7호
• /
• pp.460-470
• /
• 1980

The design of a control unit for a playback-type industrial robot is studied. Implemented for the cylindrical-coordinate type industrial robot with 5 degrees of freedom, the control unit constructed for the study consists of (i) z-80 .mu.p-based .mu.-computer control system (ii) Teach-Box for work command, and (iii) various softwares for generating signals for servo driving unit and operating the robot as playback-type. Softwares are developed by using high level Basic Language and low level z-80 Assembly Language for ease of programming and speed of program execution. To show the effectiveness, and example is included.