• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.36-39
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• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. All the magnetic components (output inductor, transformer, input filter) can be integrated into a single core. The integrated magnetics can reduce the number of the magnetic components. Developed the push pull forward converter rating are of 36 $\~$72V input and 3.3V/30A output. In this converter, the efficiency was measured by $76.4\%$ at full load and 82.95$\%$ at full load. The maximum efficiency is up to 83.$\%$ at 200kHz switching frequency, l1A output.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.155-162
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• 1994

The Japanese "Just-In-Time" technique reduces inventory and unnecessary factors. This technique makes the success of Japanese firms, therefore many Korean firms try to apply it to their situation. But the technique doesn't bare the same success in Korean firms. This paper, therefore, considers the different situations between Korean rim and Japanese firm, then simulates the Pull system and Push system for a multiline, multistage production system. This paper drives the different results of simulation according to variable processing times, variable demand, set-up time and shortages in Pull system and Push system using GPSS. The results show that the performance of Pull system is lower than Push system's in variable master production scheduling and variable processing times.ing times.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.243-249
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• 2000

This experimental study is shows speed-up possibility for the conventional railway vehicle. We appraise derailment coefficient then increase the velocity of the kyungbu line, honam line, changhang line, kyungjeon line.

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.1
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• pp.37-43
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• 2012

Purpose: This study is to evaluate the clinical results of pull-out suture for root tear of posterior horn of medial meniscus. Materials and Methods: Between March 2006 and February 2011, We studied 40 cases with the root tear of posterior horn of medial meniscus which follow up more than 1 years. Mean age was 49.5 years old. We excluded osteoarthritis or varus deformity patients more than 5 degrees. pull-out suture was performed to the patients with grade 0-2 of Kellgren and Lawrence classification. According to Outerbridge classification, evaluation of cartilage damage was performed during arthroscopy. Evaluation of clinical result was used the Lysholm score. Results: The mean pre-operation Lysholm score was 63.9 and post-operation score was 86.3. The complete failure rate was 3 of 40 cases (7.5%). Twenty of 40 cases (50%) showed cartilage lesions in weight bearing portion of medial femoral condyle which were 12 cases in grade 1, 5 cases in grade 2 and 3 cases in grade 3 according to the Outerbridge classification. Conclusion: In the treatment of pull-out suture for root tear of posterior horn of medial meniscus, exclusion of more than moderate arthritis or varus deformity is very importment. Pull-out suture seems to be a useful treatment of the root tear of posterior horn of medial meniscus in mild osteoarthritis or varus deformity of middle ages.

• Journal of the Korean Arthroscopy Society
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• v.2 no.1
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• pp.45-50
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• 1998

Recently, a variety of arthroscopic techniques have been reported for the treatment of the displaced tibial eminence fracture. The purpose of this study was to describe details of arthroscopic technique using pull-out wire and to evaluate the results. Eleven patients with irreducible type II and type III tibial eminence fractures underwent the arthroscopic reduction and internal fixation using double strand pull-out wiring. The anterior cruciate ligament tibial drill guide was utilized for the reduction of fracture and passage of the guide pins. The tibial eminence fracture was firmly fixed with double strand 26-gauge pull-out wire(0.45mm diameter). Fracture union was achieved at 7.2 weeks (range, six to eight weeks) after operation. All cases were united at the last follow-up. Subjectively, nine patients had no pain and no restriction of daily activities. Two patients with combined injuries had limitation of knee motion(10 to 130 degrees, respectively) and one patient showed mild anterior laxity. Early rehabilitation was enabled without loss of reduction and breakage of pull-out wire. The arthroscopic reduction and internal fixation using pull-out wire showed good results including early rehabilitation, early fracture union, minimal morbidity, and no requirement of the second operation for hard ware removal.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.405-411
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• 2013

Objective: Product design process without considering the strength of the user can cause the excessive burden on musculoskeletal system of human body. Since the muscle strength will vary depending on the body posture, the design of product should consider the characteristics of body posture. This study was performed to investigate the effects of forearm postures on the push and pull strength. Background: Overexerted force has been identified to cause musculoskeletal disorders. It is important to know the push and pull strength exerted by human when designing so that exerted force does not exceed the safety limits. Method: Maximum isometric push and pull strength of left, right and both hands were measured according to forearm postures with pronation, neutral and supination. For the study, 66 male and 30 female undergraduate students were participated as subjects. All subjects were normal and healthy with no clinical history. Results: The results showed that the push strength of male and female were 93.3% and 85.4% of pull strength. It showed that the strength of one-hand was 72.1~81.0% of the strength of two-hands, and the strength of left hand was 93.1~95.8% of the strength of right hand. The strength of female was 62% of the one of male. It was found that the strength with pronation $90^{\circ}$ was reduced up to 20% compared to the strength with neutral posture. Conclusion: Push and pull strength of male and female were reduced when forearm was rotated extremely. Application: The results of this study will be used for the prevention of work related musculoskeletal disorders and design of industrial equipment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.103-112
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• 2008

Pull-off test is generally used to evaluate bond strength of FRP composite with concrete at job site. However, some damages on FRP composites can not be avoided during pull-off test and moreover test range of pull-off strength is limited by maximum tensile strength of concrete. Accordingly, it is required to set-up a test method that can evaluate mechanical properties of structural adhesive indirectly prior to pull-off test. In this study, the standard test methods for structural adhesive which can simply evaluate mechanical performance of adhesive were suggested through comparative experiments from each different standard in various countries. Particularly, gluing thickness of adhesive in tensile lap-shear tests, the section dimension of compression and bending test specimens become unified, and standard test specimen size is achieved by test results.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.21 no.4
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• pp.257-263
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• 2018

Purpose: Studies on the physiology of the transposed stomach as an esophageal substitute in the form of a gastric pull-up or a gastric tube in children are limited. We conducted a study of motility and the pH of gastric esophageal substitutes using manometry and 24-hour pH measurements in 10 such patients. Methods: Manometry and 24 hour pH studies were performed on 10 children aged 24 to 55 months who had undergone gastric esophageal replacement. Results: Six gastric tubes (4, isoperistaltic; 2, reverse gastric tubes) and 4 gastric pull-ups were studied. Two gastric tubes and 4 gastric pull-ups were transhiatal. Four gastric tubes were retrosternal. The mean of the lowest pH at the midpoint of the substitute was 4.0 (range, 2.8-5.0) and in the stomach remaining below the diaphragm was 3.3 (range, 1.9-4.2). In both types of substitute, the difference between the peak and the nadir pH recorded in the intra-thoracic and the sub-diaphragmatic portion of the stomach was statistically significant (p<0.05), with the pH in the portion below the diaphragm being lower. The lowest pH values in the substitute and in the remnant stomach were noted mainly in the evening hours whereas the highest pH was noted mainly in the morning hours. All the cases showed a simultaneous rise in the intra-cavitatory pressure along the substitute while swallowing. Conclusion: The study suggested a normal gastric circadian rhythm in the gastric esophageal substitute. Mass contractions occurred in response to swallowing. The substitute may be able to effectively clear contents.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.247-255
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• 2013

In this paper, a soft switching DC-DC converter for AC module type photovoltaic (PV) module integrated converter is proposed. A push-pull converter is suitable for a low voltage PV AC module system because the step-up ratio of a high frequency transformer is high and the number of primary side switches is relatively small. However, the conventional push-pull converters do not have high efficiency because of high switching losses by hard switching and transformer losses (copper and iron losses) by high turns-ratio of the transformer. In the proposed converter, primary side switches are turned on at zero voltage switching (ZCS) condition and turned off at zero current switching (ZVS) condition through parallel resonance between secondary leakage inductance of the transformer and a resonant capacitor. Therefore the proposed push-pull converter decreases the switching loss using soft switching of the primary switches. Also, the turns-ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1303-1311
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• 2006

Most of the piles are designed as group piles. In certain geotechnical environments, the installation of group piles causes heaving of the already installed piles. The unfavorable effects of pile heaving on pile bearing capacity have been well known to field engineers. However not many engineers pay enough attention to this subject. According to our recent researches, not only the bearing capacity but also the pile material could be seriously damaged due to the installation of nearby piles, especially with the cases of precast concrete piles. When the pull-out force due to installation of neighboring piles acting on the already installed precast concrete pile exceeds the shaft friction, pile heaving occurs. At the same time, if the pull-out force exceeds the allowable tensile strength of the precast concrete pile, tensile failure is inevitable, which is critical for the pile integrity. In other cases the pile material was not damaged but serious relaxation occurred as the results of pile heaving. In this paper, the pull-out mechanism due to the installation of group piles is explained.