• Journal of Power Electronics
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• 제18권2호
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.206.2-206.2
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• 2005

• The Korean Journal of Pain
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• 제11권1호
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• pp.150-154
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• 1998

Epidural steroid injection have become one of the most frequently applied conservative option for the management of acute and chronic back pain. As the indications for epidural steroid injections increase so do the adverse responses associated with this procedure. This study reports the succession of 3 patients who developed galactorrhea and hyperprolactinemia after recieving an epidural steroid injection for lumbar radiculopathy and low back pain. Serum prolactin level was elevated in accordance with epidural injection of corticosteroid. We measured the serum prolactin level by immunoradiometric assay method and peak serum prolactin level at above 500, 144.2, 150.3 ng/ml respectively. Also we found the serum prolactin level decreased to normal values 3 wks after corticosteroid injection. Galactorrhra ceased in advance of decrease of serum prolactin level. That "Hyperprolactinemia and galactorrhea can occur following epidural steroid injection", requires a much larger prospective investigation.

• The Korean Journal of Pain
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• 제18권1호
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• pp.23-28
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• 2005

Background: An epidural steroid injection (ESI) is usually used for the treatment of low back pain with radiculopathy. An ESI can be performed by two procedures: I) a lumbar or caudal epidural steroid injection and II) a transforaminal epidural steroid injection. Methods: Ninety-three patients, who had undergone transforaminal epidural steroid injection (Group II), and either a lumbar or caudal epidural steroid injection (Group I), were retrospectively studied. The authors assessed the pain, walking, standing improvement and side effects after each procedure, which were evaluated as being very good, good, fair or poor. Data were collected from the patients medical records and analyzed using the chi-squared test. P < 0.05 was considered significant. Results: There were no statistically significant differences in the pain, walking, standing improvement and side effects between the two groups. However, there was a statistically significant difference in the pain improvement following transforaminal epidural steroid injection in those not effectively responding to an initial lumbar or caudal epidural block in Group II. Conclusions: A transforaminal epidural steroid injection is a useful alternative to a lumbar or caudal epidural steroid injection for low back pain with radiculopathy.

• 한국산학기술학회논문지
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• 제20권2호
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• pp.638-643
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• 2019

자동차 소프트 인스트루먼트 패널의 비용과 중량을 줄이기 위하여 두 가지 사출을 동시에 수행하는 방법을 이용한 새로운 인스투르먼트 패널이 개발되었다. 첫 번째 사출은 뒷면 발포체 포일을 삽입하는 압축 사출을 하는 방법이고, 다른 하나는 동승석 에어백에 도어와 동시에 2샷 사출하는 방법이다. 우리는 그것을 'IMX-IP'라고 부르며, 이것은 인스트루먼트 패널의 모든 부품들이 종류가 다른 수지와 하나의 금형 안에서 만들어지는 방법인 것이다. 본 기술의 개발 과정은 (1) TRIZ 기법을 이용한 새로운 사출 금형 설계, (2) 사출 조건의 최적화와 폼의 손실과 두께 편차를 최소화하기 위한 뒷면 발포체 포일의 최적화, (3) 2샷 사출 압축에 대한 CAE 해석 검증, (4) 신뢰성 검증 시험과 양산에의 적용 순서로 이루어져 있다. 뒷면 발포체 포일 삽입을 이용한 2샷 사출을 통한 공정 감소는 개발비와 중량 절감과 함께 소프트 인스투루먼트 패널의 부드러운 느낌을 향상시키는 것을 가능하게 하였다.

• 한국분무공학회지
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• 제3권2호
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• pp.24-33
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• 1998

The characteristics of liquefied butane spray are expected to be different from conventional diesel fuel spray, because a kind of flash boiling spray is expected when the back pressure is below the saturation vapor pressure of the butane(0.23MPa at $25^{\circ}C$). An accumulator type pintle injector and its fuel delivery system has been simulated in ruder to give injection pressure, needle lift and rate of fuel injected. The governing equation were solved by finite difference metho. The injection duration was controlled by solenoid valve. Spray behaviors such as a transient spray tip penetration, spray angle and SMD were calculated based on the empirical correlations in case that the back pressure is both above the vapor pressure of the butane and below that of butane. When the back preassure is below the vapor pressure of the fuel, conventional correlation is modified to represent the effect of flash boiling.

• 한국생산제조학회지
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• 제18권4호
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• pp.430-435
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• 2009

The cooling stage greatly affects the product quality in the injection molding process. The cooling system that minimizes temperature variance in the product surface will improve the quality and the productivity of products. The cooling circuit optimization problem that was once solved by a response surface method with 4 design variables. It took too much time for the optimization as an industrial design tool. It is desirable to reduce the optimization time. Therefore, we tried the back-propagation algorithm of artificial neural network(BPN) to find an optimum solution in the cooling circuit design in this research. We tried various ways to select training points for the BPN. The same optimum solution was obtained by applying the BPN with reduced number of training points by the fractional factorial design.

• Journal of Korean Neurosurgical Society
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• 제60권2호
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• pp.205-210
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• 2017

Objective : This study was performed to evaluate and compare the efficacies of caudal epidural injections performed at prone and lateral decubitus positions. Methods : A total of 120 patients suffering from low back pain and radicular leg pain were included and patients were randomly distributed into 2 groups according to the position during injection. In Group 1 (n=60; 32 women, 28 men), caudal epidural injection was performed at prone position, whereas it was implemented at lateral decubitus position in Group 2 (n=60; 33 women, 27 men). Visual analogue scale, Oswestry Disability Index (ODI), walking tolerance (WT) and standing tolerance (ST) were compared in 2 groups before and after injection. Results : In Group 1, ODI values were higher at 30th minute (p=0.007), 3rd week (p=0.043) and 6th month (p=0.013). In Group 1, ODI, VAS and ST values were improved significantly at all follow-up periods compared to initial values. In Group 1, WT scores were better than initial values at 30th minute, 3rd week and 3rd month. In Group 2, ODI scores at 30th minute, 3rd week, 3rd month and 6th month were improved while VAS and ST scores were improved at all periods after injection. WT scores were better at 30th minute, 3rd week and 3rd month compared to initial WT scores. Conclusion : Our results indicated that application of injection procedure at lateral decubitus position allowing a more concentrated local distribution may provide better relief of pain.

• Journal of Korean Biological Nursing Science
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• 제19권1호
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• pp.11-17
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• 2017

Purpose: To determine the effects of neck and back touch on Ultrasonic Vocalization (UV) and the Rat Grimace Scale (RGS) in rats touched by the human hand as an intervention for reducing pain and anxiety associated with intramuscular injections. Methods: This study was a randomized, controlled, pre-test/post-test design study. Twenty male Sprague-Dawley rats were assigned to either the experimental or control groups (n= 10 rats/group). The experimental group was touched in a manner similar to massaging the rat's neck and back twice a day for one week. The two groups received two intramuscular injections. The 22kHz and 50kHz UV and the RGS scores were measured before and after each intramuscular injection. Results: The 22kHz UV and RGS score were significantly higher in the control group than in the experimental group when the first intramuscular injection was administered; whereas, no difference between the experimental and the control groups were observed when the second intramuscular injection was administered. There was no statistical difference in the 50kHz UV between the two groups when the first and second injections were administered. Conclusion: This study found that touching was an effective intervention method to reduce negative emotions and pain in rats receiving their first intramuscular injection.

• 소성∙가공
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• 제18권2호
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• pp.177-182
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• 2009

A work of thin-walled outsell injection molding technology for a plastic part of moldframe applicable in a display product was performed in the present study. The thin-walled plastic part is one of the core parts in the display product, which supports and protects a light guide plate and back light unit from external environmental conditions. It globally has the shape of rectangular and surrounds the light guide plate and back light unit for each class of inch, however, the cross section of the part is not clear to define the thickness. This causes the difficult problem of injection molding itself for the part. Moreover, a metal outsell part makes a difficult problem in injection molding over it. Because the mold temperature control of the parts are not uniform in thickness direction due to the metal part. A careful injection melding analysis and injection mold design from the analysis results have to be proceeded to obtain a production of precision moldframe. Therefore, optimization for injection molding process and analysis of warpage characteristics were studied. Consequently, it was possible from the presented virtual manufacturing process that the manufacturing of precision thin-walled outsell moldframe.