• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1042-1050
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• 2003

A heating flow discharged from a 4-way ceiling type indoor unit has been investigated to determine the design parameters for the optimal flow control. The flow was measured by a PIV(particle image velocimetry) system and an experimental model of 1/10 scale with a transparent room was devised by satisfying the Archimedes number. This similarity is generally used in cases where the forced convection has similar magnitude of the natural convection. To optimize the heating flow, several vane angles and vane control algorithms of cross and right angle controls were considered. Regarding the vane angle, experimental results show that 30$^{\circ}$is an optimal angle to avoid re-suction flows without significant increase in flow noise. Temperature distribution measured in the environmental chamber ensures the increased thermal comfort when compared to the case, 60$^{\circ}$angle. At the optimal angle, applying open/close control gives rise to more uniform distribution of the heating flow than without control. Especially, the cross-control seems to be satisfactory for thermal comfort.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.533-536
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• 2002

A heating flow discharged from a 4-way ceiling type indoor unit has been investigated using a PIV(particle image velocimetry) system For the PIV measurements, an experimental model of 1/10 scale with a transparent room was devised by satisfying the Archimedes number, which is generally used in case that the forced convection has the similar magnitude as the natural convection. To optimize the heating flow, several vane angles and vane control algorithms of cross and right angle controls were considered. Regarding the vane angle, the experimental results show that it should be less than $30^{\circ}$ to avoid re-suction flows which decrease the performance of the air-conditioner. At the vane angle of $30^{\circ}$, applying open/close control gives nae to more uniform distribution of the heating flow than without control. Especially, the cross-control seems to be satisfactory for the thermal comfort.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.689-692
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• 2008

Noises from ceiling mounted air-conditioning units were recorded in various actual situations such as offices, classrooms and libraries. Eight specimens of air-conditioners from major domestic and foreign manufacturers' were investigated in this study. A head and torso simulator was located 1.5 m beneath the air-conditioner panel for the measurements and sound pressure levels of the recording sounds were varied from 28 to 55 dBA with 3 dB steps for subjective evaluations. A total of 88 stimuli was randomly presented to subjects using a headphone system in semi-anechoic chamber. Two-categorized (noisiness and amenity) nine-point scale was used as evaluation method. The third scale ('point 3') among the nine-point scale was set as the threshold of allowable level of the air-conditioning sounds in consideration of the real situations. The results indicate that the allowable sound pressure level is around 34 dBA for both noisiness and amenity categories.

• Journal of The Korea Institute of Healthcare Architecture
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• v.14 no.4
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• pp.39-46
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• 2008

Construction and operation of Germ Free Pigs' facilities are very expensive because pigs' rooms and other major rooms of the facility require germfree environments. Especially, running the HVAC system of aseptic facilities requires a lot of expenses. However, proper location and efficient shape of outlets/inlets for the ventilation of the room can reduce the excessive running cost. In order to do that, this study proposes alternative location and shape of ventilation outlets/inlets to the existing design pattern in germfree pigs' room. The design condition of this study is the maintenance of adequate temperature(24$^{\circ}C$, $NH_3$concentration level(below 1.5 ppm), and air stream speed(below .25m/sec) in the pigs' room for the summer and the winter together. As the Software Program, FLUENT(Ver. 6.2) has been used for the analysis of proposed ventilation patterns. In conclusion, wall inlets and ceiling inlet/outlet are advisable in summer, wall inlets and ceiling outlets is advisable in winter. As far as the shape is concerned, diffuser type for the ceiling outlet is desirable.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.4
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• pp.25-33
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• 2018

In regard to modular systems, new methods, as well as middle and high-story unit design ideas, are currently being studied. These studies need to focus on the enhanced stiffness and seismic performance of these connections, and see that the development of fully restrained moment connections can improve the seismic performance. For this reason, this study evaluates the performance of the connections of the ceiling bracket-typed modular system through repeated loading tests and analyses. In order to compare them with these modular units, new unit specimens with the bracket connection being different from that of the traditional modular unit specimens were designed, and the results of repeated loading tests were analyzed. In the traditional units, the structural performances of both welding connection and bolt connection were evaluated. In regard to the testing results, the initial stiffness of the hysteresis curve was compared with the theoretical initial stiffness, and the features of all specimens were also analyzed with regard to the maximum moment. In addition, the test results were examined with regard to the connection flexural strength of the steel special moment frame specified under the construction criteria KBC2016. The connections, which were proposed in the test results, were found to be fully restrained moment connections for designing strong column-weak beams and meeting the requirements of seismic performance of special moment frames.

• Architectural research
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• v.1 no.1
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• pp.47-53
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• 1999

An interesting of desktop air-conditioning system is the Personal Environmental Module(PEM) System. The PEM system allows the occupant to choose the desired temperature, air volume and direction of the discharged air. In this study, the measurements on the age of air and the air change effectiveness, using the tracer gas method, are carried out to analyze the ventilation performance for provision of fresh air near the breathing zone by the PEM. The relations between the PEM for optimal control and other factors related to indoor air quality, and the ventilation for the PEM are examined. Also, three different supply diffuser types(desktop, floor and ceiling) are compared in view of their ability to distribute supply air to the workstation breathing zone. The desktop diffuser type could deliver air directly to the occupants breathing zone with a high degree of effectiveness. The minimum local age of air was measured in the breathing zone, which is directly supplied with air from the PEM diffusers, and the measured local air change effectiveness of the desktop diffuser in the breathing zone was about 1.13 to 1.23 times greater than that of the ceiling and floor diffusers. When the minimum outside air change rate as specified using ASHRAE Standard 62R is supplied with a desktop diffuser type, the volume of outside air can be reduced 13 to 23%, resulting in a commensurate in ventilation energy use.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1028-1033
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• 2008

The mount type HVAC control system is a type of an HVAC control system which is installed between a ceiling and ceiling boards of a room to control room temperature. Although the device is quite popular, design is conducted by a conventional way where engineering intuition and experiences are utilized. It is found that the design process is fairly inefficient and time-consuming because there are a lot of feedbacks. The axiomatic approach is used to investigate the design characteristics of the mount type HAVC control system and the Independence Axiom is utilized for the investigation. The Overall hierarchy is established up to the level of parts. It is found that the current design has many coupled and redundant aspects. The hierarchy is reorganized based on the Independence Axiom and a new design process is found. To exploit the new design process in practice, a design manual is made.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.39-48
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• 2015

In this study, granting the optimal loan limit on SME (Small and Medium Enterprise) loans of financial institutions was proposed using the traditional newsvendor model. This study was the first domestic case study that applied the newsvendor model that was mainly used to calculate the optimum order quantity under some uncertain demands to the calculation of the loan limit (debt ceiling) of institutions. The method presented in this study made it possible to calculate the loan limit (debt ceiling) to maximize the revenue of a financial institution using probability functions, applied the newsvendor model setting the order volume of merchandise goods as the loan product order volume of the financial institution, and proposed, through the analysis of empirical data, the availability of additional loan to the borrower and the reduction of the debt ceiling and a management method for the recovery of the borrower who could not generate profit. In addition, the profit based loan money management model presented in this study also demonstrated that it also contributed to some extent to the prediction of the bankruptcy of the borrowing SME (Small and Medium Enterprise), as well as the calculation of the loan limit based on profit, by deriving the result values that the borrowing SME (Small and Medium Enterprise) actually went through bankruptcy at later times once the model had generated a signal of loan recovery for them during the validation of empirical data. accordingly, The method presented in this study suggested a methodology to generated a signal of loan recovery to reduce the losses by the bankruptcy.

• Korea Journal of Hospital Management
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• v.29 no.2
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• pp.37-47
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• 2024

Purpose: This study aimed to determine the effect of adjusted out-of-pocket maximum rules in the 'differential co-payment ceiling', which means having a higher burden of co-payment, that expanded to the entire ceiling level in long-stay admission patients in long-term care hospitals(LTCH). Methodology: We used health insurance claim data between January 1, 2022, and December 31, 2022 received from the National Health Insurance Service. The study populations were inpatients in long-term care hospitals more than 1 days during the study period. We performed the difference in characteristics of the LTCH patient of the differential and general ceiling by the chi-square test. We estimated the change of the population, cost, and co-payments per person under the assumption of restructuring. Finding: Based on adjusted out-of-pocket maximum rules in 2023, it was expected that the number of benefits decreases at the high-income level while increasing at the low-income level. The burden of health expenditure after reimbursement of co-payment ceiling, is expected to increase by 65.1% in the highest medical necessity, whereas the low medical necessity would decreases compared to 2022. Practical Implications: The results demonstrate that the current out-of-pocket maximum rules do not reflect the needs of medical necessity. This study suggested the need to reflect the medical necessity in LTCH on the out-of-pocket maximum rules in the future.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.285-290
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• 1998

The purpose of this study is the design of the climate chamber. Experiments was performed in a climate chamber that was running Under Floor Air-Conditioning System(UFAC). The chamber has a diffuser in the middle of the floor, and exhausts on the ceiling, simulating underfloor air conditioning system.