• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.27-35
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• 1998

An experimental study was performed to investigate the optimum cycle of an inverter heat pump as a function of frequency. The performance of the inverter heat pump with the rated cooling capacity of 4,141 W(3,550kcal/h) was measured with a variation of frequency, indoor and outdoor temperature, and length of capillary tube in the psychrometric test room. As a base case, the inverter heat pump with the standard capillary length of l,000mm(optimum size for the frequency of 60Hz) and ASHRAE Test condition "A" was tested by varying frequency from 30Hz to 80Hz. Then, the optimum cycles were investigated by varying the length of capillary tube at each frequency level of 30, 60 and 80Hz. Based on the experimental data, the change of system characteristics between the optimum and the base case were analyzed for each selected frequency level. Generally, for low frequency level(30Hz), the longer length of the capillary tube compared with the standard size showed the higher energy efficiency ratio(EER), while for high frequency level(80Hz) the shorter length of the capillary tube showed the higher EER.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.64-72
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• 1997

An experiment study was performed to investigate the optimum cycle of an inverter heat pump as a function of frequency. The performance of the inverter heat pump with the rated cooling capacity of 4141W(3550kcal/h) was measured with a variation of frequency, indoor and outdoor temperature, and length of capillary tube in the psychrometric test room. As a base case, the inverter heat pump with the standard capillary length of 1000mm which was optimum size for the frequency of 60Hz and ARHRAE Test condition A was tested by varying frequency from 30Hz to 80Hz. Then, the optimum cycle was invesigated by varying the length of capillary tube at each frequency levels of 30, 60 and 80Hz. Based on the experimental data, the change of system characteristics between the optimum and the base case were analyzed for each selected frequency levels. Generally, for low frequency level(30Hz), the longer length of the capillary tube compared with the standard size showed the higher EER, while for high frequency level(80Hz) the shorter length of the capillary tube showed the higher EER.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.389-395
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• 2014

In this study, we discussed the weight reducing of 2 MW class of wind turbine rotor shaft by optimizing design method. The optimal design was applied to obtain get an optimized structure and parameters for the base structure using FEA and DOE. The results were verified by comparing the maximum von Mises stresses and maximum volume in the case of the existing design with those in the case of the optimized design. It was shown that the weight of a base structure can be reduced by about 23 %.

• Plant Journal
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• v.13 no.3
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• pp.26-29
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• 2017

In this research, the composition of the feed stream is optimized in pressure swing distillation for separating of methanol-acetone. It is well known that the composition of feed stream in pressure swing distillation system has a great influence on the feasibility to separate mixture. The workscope of this study is to show better separation efficiency at specified pressure by controlling the composition of feed stream with recycle of two products. Based on the base case without recycle flow, two processes are designed that methanol and acetone are recycled to feed stream, respectively. Each processes are compared with total annual cost and as a result, the base case without recycle flow are most favorable.

• Carbon letters
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• v.4 no.1
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• pp.31-35
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• 2003

The specific adsorption behaviors of activated carbons (ACs) treated with 30 wt% $H_3PO_4$ or NaOH were investigated in the removals of NO or $NH_3$. The acid and base values were determined by Boehm's titration method. And, the surface properties of ACs were studied by FT-IR and XPS analyses. Also, $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET and t-plot methods, respectively. From the adsorption tests of NO and $NH_3$, it was revealed in the case of acidic treatment on ACs that the $NH_3$ removal was more effective due to the increase of acidic functional groups in carbon surfaces. Also, the NO removal was increased, in the case of basic treatment, due to the improvement of basic functional groups, in spite of significant decreases of BET's specific surface area and total pore volume. It was found that the adsorption capacity of ACs was not only determined by the textural characteristics but also correlated with the surface functional groups in the acid-base intermolecular interactions.

• KIEAE Journal
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• v.7 no.6
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• pp.17-22
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• 2007

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This paper compares the experimental performance of two different types of air type PV/T collector units: the base case of a collector unit with 10cm gap for forced ventilation and the other unit with copper pin attached to PV module to enhance its thermal performance. The experimental results shows that the base case unit had the overall efficiency of 41.9% and the improved unit with copper pin attached to PV module had 50.1% efficiency. For these air type PV/T units, the forced ventilation of the air space improved the electrical performance as well as the thermal performance.

• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1142-1153
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• 2019

This paper presents the effect of fusion procedure on the fusion performance of the thermal butt fusion in the safety class III buried HDPE piping per various tests performed, including high speed tensile impact, free bend, blunt notched tensile, notched creep, and PENT tests. The suitability of fusion joints and qualification procedures was evaluated by comparing test results from the base material and buttfusion joints. From the notched tensile test result, it was found that the fused joints have much lower toughness than the base material. It was also identified that the notched tensile test is more desirable than the high speed tensile impact and free bend tests presented in the ASME Code Case N-755-3 as a fusion qualification test method. In addition, with regard to the single low-pressure fusion joint performances, the procedure given by the ISO 21307 was determined to be better that the one specified in the Code Case N-755-3.

• Journal of Rhinology
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• v.25 no.2
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• pp.99-102
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• 2018

Lateral pharyngoplasty is a surgical option for treatment of obstructive sleep apnea (OSA). Here, we present a case involving a 40-year-old healthy man who underwent surgery, including lateral pharyngoplasty and robotic tongue base resection, for OSA. There were no intraoperative or immediate postoperative complications. However, on postoperative day 3, the patient presented with swelling in the temporal and buccal areas and was diagnosed with subcutaneous emphysema, later confirmed by computed tomography. The patient was carefully monitored under conservative care and discharged without complications. Although subcutaneous emphysema following tonsillectomy is a rare complication and usually resolves with conservative management, in certain cases, it might require surgical intervention. Lateral pharyngoplasty involves tonsillectomy and additional incision along the tonsillar fossa, which makes it susceptible to pharyngeal wall defects and, consequently, subcutaneous emphysema. Additionally, lateral pharyngoplasty and robotic tongue base resection cause pain and might thus contribute to the increase in intrapharyngeal pressure, which might aggravate subcutaneous emphysema. Lateral pharyngoplasty should be performed with meticulous dissection of the superior pharyngeal constrictor muscle. Healthcare providers should be aware of these complications and, upon suspicion of the same, place the patient under close observation to prevent life-threatening situations.

• Journal of Korean Neurosurgical Society
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• v.66 no.5
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• pp.598-604
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• 2023

Penetrating head injury is a serious open cranial injury. In civilians, it is often caused by non-missile, low velocity flying objects that penetrate the skull through a weak cranial structure, forming intracranial foreign bodies. The intracranial foreign body can be displaced due to its special quality, shape, and location. In this paper, we report a rare case of right-to-left displacement of an airgun lead bullet after transorbital entry into the skull complicated by posttraumatic epilepsy, as a reminder to colleagues that intracranial metal foreign bodies maybe displaced intraoperatively. In addition, we have found that the presence of intracranial metallic foreign bodies may be a factor for the posttraumatic epilepsy, and their timely removal appears to be beneficial for epilepsy control.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.81-86
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• 2007

This paper presents a computer aided process planning system integrating case-based reasoning and expert system for block assembly in shipbuilding. Expert rules are extracted from the case-base where cases are represented as a set of constraint-satisfaction problems. Rules for the expert system are extracted by generalizing the constraints. In generalizing the constraints, parts are generalized as variables or as part-types. The system was developed with CLIPS, an expert system shell. As more cases are collected, more rules will be extracted and the existing rules will be updated.