• Journal of Korean Neurosurgical Society
• /
• v.30 no.sup2
• /
• pp.309-315
• /
• 2001

The term slit ventricle syndrome(SVS) refers to an episodic occurrence of headache, vomiting, and possibly some degree of impaired consciousness in shunted hydrocephalic children in whom slit-like ventricles are seen on CT scan or MRI. Authors present 6 cases with SVS who were treated at our institute for last 10 years. From 1986 to 1996, 821 patients underwent shunt surgery for hydrocephalus. The etiology of hydrocephalus included brain tumor(140 patients), post-hemorrhagic(62 patients), idiopathic normotensive hydrocephalus(64 patients), post-meningitic( 58 patients), post-traumatic(54 patients), congenital(48 patients), neurocysticercosis(31 patients), and unknown etiology(364 patients). During the mean follow-up duration of 68 months, 232 shunt revisions were performed by a revision rate of 1.28 per patient. The incidence of SVS was 0.7%(6 patients). Most of them have been operated on in infancy. Time interval from the first operation to the development of slit-ventricle syndrome ranged from 4 to 8 years, the mean was 6 years. Shuntogram showed patent shunt in all patients. Two patients with less severe clinical symptoms improved with conservative treatment. These patients were not measured ICP because of good hospital course. One patient showed high ICP and needed only revision with same pressure valve as previous shunt. Low ICP was noted in 3 patients. Pressure augmentation using an anti-siphon device(ASD) or upgrading valve system were necessary in these patients. The authors stress that determining type of SVS is the first step in treatment planning and that the best treatment is a strategy aimed at resolving the specific type of SVS responsible for the symptoms.

• Journal of the Korean Child Neurology Society
• /
• v.26 no.4
• /
• pp.284-287
• /
• 2018

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutation of one of two genes, TSC1 (encoding hamartin, 9q34) and TSC2 (encoding tuberin, 16p13). It invades the central nervous system and various parts of the body, causing various symptoms. Crohn's disease (CD) is a chronic immune-mediated disease that has not been clearly elucidated. It is thought to be caused by an excessive immune response of the body to bacteria that normally exist in the digestive tract with genetic factors. No cases have been reported in which both of the above-mentioned diseases occurred simultaneously. We report a case of CD in a patient with TSC. A 12-year-old boy was brought to our hospital because of abdominal pain. Skin lesions were observed in the TSC. Fundus examination revealed a hamartoma in the right retina. Brain magnetic resonance imaging revealed a subendothelial giant cell astrocytoma (SEGA). On the basis of these findings, he was diagnosed as having TSC. Blood test results showed increased levels of inflammatory markers. On abdominal ultrasonography, his colon walls were observed to be thickened with increased vascularity of the proximal ascending colon, ileocecal valve, and terminal ileum. Colonoscopy revealed discontinuous ulcerations and inflammations of the ileum, IC valve, and cecum, similar to those found in CD. Everolimus was administered orally for the SEGA but was discontinued frequently owing to the exacerbation of CD. The possibility of CD should be kept in mind in patients with TSC considering to undergo treatment for SEGA.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.175-181
• /
• 2019

In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.5
• /
• pp.227-234
• /
• 2018

The smart irrigation system using ICT technology is crucial for stable production of upland crops. The objective of this study was to develop a smart irrigation system that can control soil water, depending on irrigation methods, in order to improve crop production. In surface irrigation, three irrigation methods (sprinkler irrigation (SI), surface drip irrigation (SDI), and fountain irrigation (FI)) were installed on a crop field. The soil water contents were measured at 10, 20, 30, and 40 cm depth, and an automatic irrigation system controls a valve to maintain the soil water content at 10 cm to be 30%. In subsurface drip irrigation (SSDI), the drip lines were installed at a depth of 20 cm. Controlled drainage system (CDS) was managed with two ground water level (30 cm and 60 cm). The seasonal irrigation amounts were 96.4 ton/10a (SDI), 119.5 ton/10a (FI), and 113 ton/10a (SI), respectively. Since SDI system supplied water near the root zone of plants, the water was saved by 23.9% and 17.3%, compared with FI and SI, respectively. In SSDI, the mean soil water content was 38.8%, which was 10.8% higher than the value at the control treatment. In CDS, the water contents were greatly affected by the ground water level; the water contents at the surface zone with 30 cm ground water level was 9.4% higher than the values with 60 cm ground water level. In conclusion, this smart irrigation system can reduce production costs of upland crops.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.3
• /
• pp.343-350
• /
• 2012

A planar solid oxide fuel cell (PSOFC) is studied in its application in a high-temperature stationary power plant. Even though PSOFCs with external reformers are designed for application from the distributed power source to the central power plant, such PSOFCs may sacrifice more system efficiency than internally reformed SOFCs. In this study, modeling of the PSOFC with an external reformer was developed to analyze the feasibility of thermal energy utilization for the external reformer. The PSOFC system model includes the stack, reformer, burner, heat exchanger, blower, pump, PID controller, 3-way valve, reactor, mixer, and steam separator. The model was developed under the Matlab/Simulink environment with Thermolib$^{(R)}$ modules. The model was used to study the system performance according to its configuration. Three configurations of the SOFC system were selected for the comparison of the system performance. The system configuration considered the cathode recirculation, thermal sources for the external reformer, heat-up of operating gases, and condensate anode off-gas for the enhancement of the fuel concentration. The simulation results show that the magnitude of the electric efficiency of the PSOFC system for Case 2 is 12.13% higher than that for Case 1 (reference case), and the thermal efficiency of the PSOFC system for Case 3 is 76.12%, which is the highest of all the cases investigated.

• Journal of Aerospace System Engineering
• /
• v.12 no.4
• /
• pp.49-56
• /
• 2018

In this paper, the performance analysis and the experiment of the brake system using the small piezoelectric-hydraulic pump were performed. Initially, the 3-D modeling of the brake load components was performed for the construction of the brake system. Subsequently, modeling using the commercial program AMESim was performed. A floating caliper model was used as a load for modeling the brake system. Through the AMESim simulation, load pressure, check valve displacement and flow rate under no load state were calculated, and performance analysis and changes in dynamic characteristics were confirmed by adding brake load. A jig for use in fixing the brake load during performance test was manufactured. The flow rate was assessed under no load condition and load pressure formation experiments were performed and compared with simulation results. Experimental results revealed the maximum load pressure as about 73bar at 130Hz and the maximum flow rate as about 203cc/min at 145Hz, which satisfied the requirement of small- and medium-sized UAV braking system. In addition, simulation results revealed that the load pressure and discharge flow rate were within 6% and 5%, respectively. Apparently, the modeling is expected to be effective for brake performance analysis.

• Journal of the Korean Institute of Gas
• /
• v.18 no.4
• /
• pp.13-20
• /
• 2014

In natural gas distribution system, gas pressure is regulated correspond to requirement using throttle valve which is releasing huge pressure energy as useless form. The waste pressure can be recovered by using turbo machinery devices such as a turbo expander. In this process, excessive temperature drop occurs due to Joule-Thompson effect during the expansion process. Installing natural gas boiler before or after the turbo expander prevents temperature drop. Fuel cell or gas engine hybrid system further improve the efficiency, but 1~2% of total transporting natural gas is used for operating the hybrid system. In this study, a heat pump system is proposed as a preheating device which can be operated without using transporting natural gas. Thermodynamic analysis on evaporating and condensing temperatures and refrigerants is conducted. Results show that R717 is proper refrigerant for the hybrid system with high COP and low turbine work within the defined operating conditions. In domestic usage in Korea, the heat pump system has more economic feasibility owing to natural gas being imported with a high price of LNG form.

• Journal of Acupuncture Research
• /
• v.27 no.1
• /
• pp.1-10
• /
• 2010

Objectives : The mechanical properties of Korean electric cupping systems are studied via experimental measurements. The study aimed at establishing the fundamentals of industrialization and systemization of oriental medicine device industry, as well as improving the quality of life for many Koreans. Methods : We reviewed the studies on traditional cupping as well as modern one to fine necessary factors for electric cupping systems. To characterize the mechanical properties of Korean electric cupping systems, we measured the pressure characteristics of commercially available electric cupping system by using an automatic pressure acquisition system and a standard cup. The pumping capability was checked at 40 seconds, and the stability of the suction cup was checked at 600 seconds. We also acquired the noise level of each system in clinical setting. To check the portability of each system, we also measured its physical dimensions. We scrutinized system manuals provided by the system manufacturers. Results : It took less than 5 second to reach the pressure if the connection between the air hose and the vacuum valve of the cupping system was secure. Pressure diminished to no more than 10% for 600s for all systems. Noise levels were 55~70 dB. Increase in pressure was too fast to control for a designated vacuum level except for one product. Conclusions : The Pumping ability of the systems is impressive and reliable. Pressure retention ability of each cup is quite reliable and reproducible. Therefore, their mechanical performances were worthy of recommendation. Some of them had noise level higher than 60 dB and they were bothersome. It was also suggested that the control for low to middle pressure needed to be accomplished by the cupping system.

• Korean Journal of Radiology
• /
• v.22 no.11
• /
• pp.1764-1776
• /
• 2021

Objective: This study aimed to validate a deep learning-based fully automatic calcium scoring (coronary artery calcium [CAC]_auto) system using previously published cardiac computed tomography (CT) cohort data with the manually segmented coronary calcium scoring (CAC_hand) system as the reference standard. Materials and Methods: We developed the CAC_auto system using 100 co-registered, non-enhanced and contrast-enhanced CT scans. For the validation of the CAC_auto system, three previously published CT cohorts (n = 2985) were chosen to represent different clinical scenarios (i.e., 2647 asymptomatic, 220 symptomatic, 118 valve disease) and four CT models. The performance of the CAC_auto system in detecting coronary calcium was determined. The reliability of the system in measuring the Agatston score as compared with CAC_hand was also evaluated per vessel and per patient using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. The agreement between CAC_auto and CAC_hand based on the cardiovascular risk stratification categories (Agatston score: 0, 1-10, 11-100, 101-400, > 400) was evaluated. Results: In 2985 patients, 6218 coronary calcium lesions were identified using CAC_hand. The per-lesion sensitivity and false-positive rate of the CAC_auto system in detecting coronary calcium were 93.3% (5800 of 6218) and 0.11 false-positive lesions per patient, respectively. The CAC_auto system, in measuring the Agatston score, yielded ICCs of 0.99 for all the vessels (left main 0.91, left anterior descending 0.99, left circumflex 0.96, right coronary 0.99). The limits of agreement between CAC_auto and CAC_hand were 1.6 ± 52.2. The linearly weighted kappa value for the Agatston score categorization was 0.94. The main causes of false-positive results were image noise (29.1%, 97/333 lesions), aortic wall calcification (25.5%, 85/333 lesions), and pericardial calcification (24.3%, 81/333 lesions). Conclusion: The atlas-based CAC_auto empowered by deep learning provided accurate calcium score measurement as compared with manual method and risk category classification, which could potentially streamline CAC imaging workflows.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.8
• /
• pp.1129-1136
• /
• 2009

The paper presents the performance characteristics for a cooling system using EEV. The water cooler was used to reduce thermal deformation and contraction due to high speed of machine tools and the EEV was used for capacity control for water cooler. The apparatus was designed for hot-gas bypass system which a hot-gas can flows from outlet of compressor to the inlet of evaporator. This experiment is the intermediary study for precise temperature control through PID control. The results show that the evaporator pressure increased and refrigeration capacity decreased as the EEV opening step of hot-gas bypass increased. These results can be used as basic data for the design of effective water cooler.