Review of technologies for snow melting systems

Kwesi Mensah,최종민 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.12

Precipitation is liquid or solid water falling from clouds to the Earth’s surface. Snow is a solid precipitation in the form of ice crystals. Due to many serious problems associated with snow accumulations during winter season, the removal of snow in winter seasons, is notonly a convenience, but can as well enhance safety and prevent property damage. Residential, commercial and industrial applications ofsnow melting have gained widespread acceptance. This paper reviews the researches on snow melting systems. The most researched andcurrently used snow melting systems are hydronic, electric and infrared systems. The review showed that hydronic snow melting systemsis the most used system currently. This was observed as a result of the availability of choice of energy source options. However, the hydronicsnow melting system has long payback period. One possible solution to compensate for this problem will be to combine snowmelting systems with HVAC systems. There have been many researches on snow melting systems for pavement and bridge applicationsexcept for roof. To help minimize the collapse of buildings as a result of heavy snowfall on roofs, roof snow melting needs more attention. The paper further reviews the concept of snow building loads by comparing standard codes like ISO 4355, ASCE 7-02 and SouthKorea’s code for calculating snow building loads. The snow building load calculated by ISO 4355 represented higher value than others. The paper also presented a review on factors such as snow density and snow water equivalents in details and describes their importancein the aspect of snow melting system design.

Performance Assessment of Refrigeration Systems for Internet Data Centers

Kwesi Mensah,Selorm Kwaku Anka,Jong Min Choi 대한설비공학회 2020 대한설비공학회 학술발표대회논문집 Vol.2020 No.6

A significant amount of the total energy consumption in internet data centers is associated with the cooling systems being used in these facilities. One major reason for the high energy consumption of cooling systems for data centers is the 365 day continual operation of such units despite the annual weather and seasonal changes. Minimizing the cooling system’s energy consumption by the introduction of new mechanical energy efficient technologies, as well as redesigning of conventional system components coupled with advanced controls are just a few of research focuses for engineers, designers and researchers in this field of study. In this study, a cooling system that employs indirectly, the concept of utilizing the low temperature ambient air for cooling during low outdoor temperature seasons is introduced. The performance of the designed cooling system is investigated under varying operating conditions and the result is compared with that of a conventional cooling system for internet data centers. The experimental results indicates that the newly proposed system can save large amount of the seasonal and annual cooling energy as compared with the conventional system operating at the same conditions.

Study on the Thermal Stability of a Constant Temperature and Humidity Chamber

Kwesi Mensah,Samuel Boahen,Jong Min Choi 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.11

Modern climatic chambers for temperature and humidity simulations are operated over a wide range of environmental test conditions such as a temperature (-70 ℃ to 200 ℃) and a relative humidity (10% RH to 98%RH) for biological items and industrial products. The stability and fluctuation control of these thermal-environmental conditions are critical for the preservation of the test specimen and products. Even though climatic test chambers are found in many industries and companies, rare literature and data is found on the experimental investigation of the stability of these climatic test chambers. In this study, an experimental investigation on the possibility of minimizing fluctuations and ensuring stability, by the adoption of a variable speed compressor to the refrigerating unit of a 400-Liter temperature and humidity chamber is carried out. It is found that, adopting a variable speed compressor to the refrigeration unit has a significant potential to ensure stability of climatic chambers with an added advantage of energy savings for a given operating and surrounding conditions.

지열원 히트펌프 시스템 적용 온실 내부 열환경 제어 특성 연구

Kwesi Mensah,최종민(Jong Min Choi) 한국신재생에너지학회 2018 한국신재생에너지학회 학술대회논문집 Vol.2018 No.11

Occupational Health and Safety and Organizational Commitment: Evidence from the Ghanaian Mining Industry

Kwesi Amponsah-Tawiah,Justice Mensah 한국산업안전보건공단 산업안전보건연구원 2016 Safety and health at work Vol.7 No.3

Background: This study seeks to examine the relationship and impact of occupational health and safety on employees’ organizational commitment in Ghana’s mining industry. The study explores occupational health and safety and the different dimensions of organizational commitment. Methods: A cross-sectional survey design was used for this study. The respondents were selected based on simple random sampling. Out of 400 questionnaires administered, 370 were returned (77.3% male and 22.7% female) and used for the study. Correlation and multiple regression analysis were used to determine the relationship and impact between the variables. Results: The findings of this study revealed positive and significant relationship between occupational health and safety management, and affective, normative, and continuance commitment. Additionally, the results revealed the significant impact of occupational health and safety on affective, normative, and continuance commitment. Conclusion: Management within the mining sector of Ghana must recognize the fact that workers who feel healthy and safe in the performance of their duties, develop emotional attachment and have a sense of obligation to their organization and are most likely committed to the organization. Employees do not just become committed to the organization; rather, they expect management to first think about their health and safety needs by instituting good and sound policy measures. Thus, management should invest in the protection of employees’ health and safety in organizations.

지중열교환기 TRT 성능 시험 방법 연구

Kwesi Mensah,이광호(Kwang Ho Lee),도성록(Sung Lok Do),최종민(Jong Min Choi) 한국신재생에너지학회 2019 한국신재생에너지학회 학술대회논문집 Vol.2019 No.5

Governance Perspectives of Human Security in Africa

( Kwesi Aning ),( Ernest Ansah Lartey ) 서울대학교 통일평화연구원 2019 Asian Journal of Peacebuilding Vol.7 No.2

Human security should not be considered as a mere academic rhetoric―it is, in fact, a political tool aimed at transforming individuals from conditions of exploitation and domination to that of political participation and accountability. This paper adopts political governance perspectives to analyze human security in Africa. It argues that without accountable democratic governance, the expressed objectives of human security would be difficult to achieve in Africa. By this focus, the paper adopts a broader view of human security, satisfying both the governance and development prerequisites of the concept, which has underpinned [in] security in Africa. The overall estimation of human security in Africa is that only a marginal improvement has been made in the region, especially over the last decade.

DEVELOPMENT OF DATA BASE FOR SNOW WEIGHT LOAD FOR THE REPUBLIC OF KOREA

Kwesi Mensah,Seung Byung Park,Han Byeoul Jang,Jong Min Choi 한국신재생에너지학회 2015 AFORE Vol.2015 No.11

지중열교환기의 고밀도폴리에틸렌 배관 형상에 따른 열전달 성능 특성에 대한 수치해석적 연구

Kwesi Mensah,최종민(Jong Min Choi) 한국지열·수열에너지학회 2016 한국지열에너지학회논문집 Vol.12 No.4

A ground source heat pump (GSHP) system is recommended as a heating and cooling system to solve the pending energy problem in the field of air conditioning, because it has the highest efficiency. However, higher initial construction cost works as a barrier to the promotion and dissemination of GSHP system. In this study, numerical analysis on the characteristics of high density polyethylene (HDPE) pipe with spiral inside was executed. The heat transfer and flow characteristics of it were compared with those of a conventional smooth HDPE pipe. The heat transfer coefficient and pressure drop of the spiral HDPE pipe were higher than those of the smooth HDPE pipes at the same fluid flow rate. By decreasing the flow rate, the spiral HDPE pipe represented similar values of heat transfer coefficient and pressure drop to the smooth HDPE pipe. The lower flow rate of the spiral HDPE pipe comparing with it of the smooth HDPE pipe is estimated to reduce the length of the ground loop heat exchanger.

Work Pressure and Safety Behaviors among Health Workers in Ghana: The Moderating Role of Management Commitment to Safety

Kwesi Amponsah-Tawaih,Michael Appiah Adu 한국산업안전보건공단 산업안전보건연구원 2016 Safety and health at work Vol.7 No.4

Background: safety and healthy working environment has received numerous research attention over the years. Majority of these researches seem to have been conducted in the construction industry, with little attention in the health sector. Nonetheless, there are couple of studies conducted in Africa that suggest pressure in hospitals. Therefore the aim of the study was to examine how pressure influence safety behavior in the hospitals. With reference to the relevance of safety behavior in primary health care delivery, there was the need for the study. Method: Data was obtained from 422 public hospital employees. Respondents were assured that all information would be kept confidential to increase the response rate and acquire more accurate information. Collection of questionnaires from participants took four weeks (20 working days), after which the data was analyzed. Results: The result of the study showed that work pressure correlated negatively with safety behavior. General safety climate significantly correlated positively with safety behavior and negatively with work pressure, although the effect size for the latter was smaller. Hierarchical regression analysis showed management commitment to safety to moderate the relationship between work pressure and safety behavior. Conclusion: When employees perceive safety communication, safety systems and training to be positive, they seem to comply with safety rules and procedures than voluntarily participate in safety activities.