• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.422-425
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• 2008

Recently, electronic products and related parts are required to have thin thickness because of small form factor. To go with the trend, LGP(light guide plate) of LCD BLU(Liquid Crystal Display Back light unit: It is one of kernel parts of LCD) for cell phone has the thickness of 0.3 mm and the battery case of cell phone has 0.25 mm. Accordingly, high speed injection molding is required to make products which have thin thickness. High speed injection molding means that the resin is injected into the cavity at higher than normal speed avoiding short shot. In the case of hydro-mechanical high speed injection machine, it requires the design for hydraulic unit to make high injection speed and the design for control unit to control hydraulic unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3 mm thickness.

• 소성∙가공
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• 제17권8호
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• pp.657-661
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• 2008

Recently, products of electronic industry and related parts are required to have the thickness thinner and thinner to reduce the part weight. To go with this trend, LGP(light guide plate) of LCD-BLU(Liquid Crystal Display-Back Light Unit: It is one of kernel parts of LCD) for cell phone has the thickness of ${\sim}0.3mm$ and the battery case of cell phone has ${\sim}0.25mm$. Accordingly, high speed injection molding is required to mold products which have thinner parts. To achieve high speed injection and proper control of hydraulic unit, various design was applied to conventional injection unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3mm thickness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.708-714
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• 2001

Although LP gas has lots of advantages, there has been limitation in application for automotive engine due to the several disadvantages, such as power decrease, complex fuel supply unit, and back fire etc. However LP gas direct injection engine has possibility to solve the problems above mentioned. LEM(Light Extinction Method) was employed for analysis of spacial and temporal distribution of LP gas which is directly injected into combustion chamber under various pressure and temperature conditions. The results from CVC(Constant Volume Chamber) were compared to those of RICEM(Rapid Induction, Compression and Expansion Machine) which simulate early- and late injection of direct injection engine. LPG fuel spray is affected by temperature and pressure in evaporation characteristics but it is more benefit to direct injection engine in every way such as, fuel distribution, evaporating speed and well wetting reduction.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권2호
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• pp.113-115
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• 2000

The gradual hole injection LIGBT (GI-LIGBT) which employs the dual gate and the p+ injector, was fabricated for eliminating a negative resistance regime and reducing a forward voltage drop in SA-LIGBT. The elimination of the negative resistance regime is successfully achieved by initiating the hole injection gradually. Furthermore, the experimental results show that the forward voltage drop of GI-LIGBT decreases by lV at the current density of 200 $A/cm^2$, when compared with that of the conventional SA-LIGBT. It is also found that the improvement in the on-state characteristics can be obtained without sacrificing the inherent fast switching characteristics of SA-LIGBT.

• Annals of Clinical Neurophysiology
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• 제12권1호
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• pp.1-2
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• 2010

Chronic non-specific low back pain (CLBP) is one of the major health problems casting substantial amount of economic expenses and negative impact on quality of life onto an individual as well as society. On contrary to public familiarity, the ways of management of CLBP are diverse and there is yet no general consensus about which approach is better than others or to whom the specific management should be applied. Some hold the negative point of view on the efficacy of the invasive maneuver such as epidural injection because there is no controlled clinical trial (RCT) yielding better long term outcome of those invasive managements over conservative ones. But the experts of interventional or surgical treatment stress the methodological difficulty in performing RCT and assert that those invasive treatments can bring the prompt and complete resolution of low back pain and restoration of function in appropriately selected cases. These seemingly opposite views on the invasive management on CLBP are rather complimentary each other than to be contradictory.

• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1194-1205
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• 2005

The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to a high pressure common-rail type fuel injection system for the control capability of the high pressure injector's needle and firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector's needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector, both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For the evaluation of the needle response of the above two injectors, we indirectly estimated the needle's behavior with an accelerometer and injection rate measurement employing Bosch's method was conducted. The experimental results show that the spray tip penetrations of piezo­driven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope in piezo-driven injector by altering the induced current.

• Fibers and Polymers
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• 제7권4호
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• pp.404-413
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• 2006

This study examines multiple quality optimization of the injection molding for Polyether Ether Ketone (PEEK). It also looks into the dimensional deviation and strength of screws that are reduced and improved for the molding quality, respectively. This study applies the Taguchi method to cut down on the number of experiments and combines grey relational analysis to determine the optimal processing parameters for multiple quality characteristics. The quality characteristics of this experiment are the screws' outer diameter, tensile strength and twisting strength. First, one should determine the processing parameters that may affect the injection molding with the $L_{18}(2^1{\times}3^7)$ orthogonal, including mold temperature, pre-plasticity amount, injection pressure, injection speed, screw speed, packing pressure, packing time and cooling time. Then, the grey relational analysis, whose response table and response graph indicate the optimum processing parameters for multiple quality characteristics, is applied to resolve this drawback. The Taguchi method only takes a single quality characteristic into consideration. Finally, a processing parameter prediction system is established by using the back-propagation neural network. The percentage errors all fall within 2%, between the predicted values and the target values. This reveals that the prediction system established in this study produces excellent results.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.581-590
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• 2005

The grouting method is widely used as the impermeable effect and ground reinforcement in construction. But, it has a problem that cement and grout material are not mixed well in the injection tip equipment and an opposite flow and interception state of the chemical grouting is happened. so, continuous work is difficult. McG method installed a special grouting and device, made possible go well mixing of grouting material and prevent flowing backward and block of nozzle also diversify powder rate of cement that is grouting material to select sutible material in layer conditions. YSS that lowered $Na_2O$ influencing durability and circumstance is developed by gel-forming reaction material. so eco-circumstance and durability is increased by minimizing dissolution of underground water. In this study, it is assumed that seepage state of the injection material using a special injection tip equipment and a unconfined compressive strenth by mixing a various injection material of various. And it is confirmed that strenth increase effect and permeable decrease of the improved body through the test execution and field execution.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.251-256
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• 2003

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors, solenoid-driven and piezo-driven type, with different electric driving characteristics So, three common-rail injectors with different electric current wave were used in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. Also the CFD analysis was carried out for fuel behavior under high pressure in between needle and nozzle of solenoid-driven injector to know the condition of initial injection at experiment test. It was found that pilot injection of common-rail system was effected by rate of injection and temperature of injected fuel and electrical characteristic of the driven injector.

• 대한환경공학회지
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• 제27권1호
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• pp.52-58
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• 2005

국내 정수장의 약품공정을 향상시켜 저비용 고효율의 정수처리 공정을 확립할 목적으로 약품 분사용 초음파 분사 노즐의 적용가능성을 평가하였다. 초음파 분사노즐은 압전세라믹스를 이용하여 제작하였으며, 이 장치를 사용하여 상수 원수를 처리한 결과와 현재 대부분의 정수장에서 사용되고 있는 기존의 약품 혼화방식에 의한 오염물질의 처리효율을 비교 평가하였다. 그 결과 혼화방식에 따른 혼화지 내 응집제 혼화특성은 초음파 노즐에 의한 혼화방식이 기계식(back-mixing) 혼화방식보다 응집제의 확산속도가 빠른 것으로 조사되었다. 오염물질 별 제거효율 역시 기계식(back-mixing) 혼화방식보다 초음파 노즐에 의한 혼화방식의 제거효율이 높은 것으로 조사되어, 초음파 분사노즐을 이용한 약품 혼화방식을 실제 정수처리 공정에 적용할 경우 응집제의 과량 주입에 의한 처리효율의 저하를 방지할 수 있고, 후속 공정에 대한 부하량을 줄임으로서, 정수공정에 사용되는 약품을 절감시키고, 혼화지가 필요없게 되어 이로 인한 경제적 효과 뿐만 아니라 보다 순도가 높은 음용수를 생산 할 수 있을 것으로 기대된다.