• Journal of Practical Engineering Education
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• v.8 no.2
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• pp.121-128
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• 2016

In injection molding process, the appearance quality issue occurs in most injection molded article. One of thermal designs for the mold was performed by increasing the cavity wall temperature with being as uniform as possible in any position. On the basis of the practical evaluation, the cavity wall temperature and finishing machined cavity surface under the optimum processing conditions are the most significant factors to avoid the appearance issue on the plastic part for a good cosmetic quality. Also, the wrong choice of gate type and location can have a considerable effect on the quality of a molded part and it's so important to keep the correct runner balance from each cavity. We've proposed the education training model of the practical tool technology course for the field oriented education to improve practical tool technology ability and optimized tooling design for injection molding quality which can be performed at the workplace substantially.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.175-182
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• 2002

The cement injection technology on the purpose of ground reinforcement and cut-off has been used in construction sites until now. However, recently it is applied to prevent leakage of underground structure. In this study, applicability of the back side waterproof grouting method was verified through performing field model tests and reviewing case histories. From the results of this study, injection shape of the back side waterproof grouting method was appeared to be root type, and waterproof effect by injection of cement grout material was excellent because grout material infiltrated into boundary between wall of structure and back side ground to be waterproof layer. Components influencing infiltration of injection material are type of soil and degree of compaction. For effective injection, injection pressure has to vary gradually from high pressure to low pessure and small quantity of injection material has to be injected for long times. Also, spacing of injection hole must be designed considering condition of back side ground, injection area, W/C ratio, the number of injection and injection pattern properly.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.285-289
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• 2007

This study presents the preform injection molding of the injection stretch-blow molding process for PET bottles. The numerical analysis of the injection molding of a preform is considered in this paper using CAE with a view to minimize the warpage. In order to determine the design parameters and processing conditions in injection molding, it is very important to establish the numerical model with physical phenomenon. In this study, a three dimensional model has been introduced for the purpose and flow simulations of filling, post-filling and cooling process are carried out. The simulations resulted in the warpage in good agreement with the measurements. Also, from the result of numerical analysis, we appropriate -ly predicted the warpage, deformation and thickness distribution along the preform wall.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.36-45
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• 1997

A spray-wall impingement model for fuel sprays is proposed and implemented as a module into the KIVA-POSTECH code. The model is based on the single droplet experiments. The droplet behaviors after impingement are determined from experimental correlations. Different behaviors of impinged droplets depend on the wall temperature and the critical temperature of the fuel. Fuel film formation is taken into account so that the model can be applicable to any wall temperature and injection conditions. Computational results on a normal and on inclined wall are in good agreement for the spray shape and penetration. More validation against experiments and development of the heat transfer model are needed for further improvement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.69-81
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• 1999

In this research computational methods for the droplet atomization and spray wall impingement are studied for the non-evaporating diesel fuel spray. The TAB(Taylor Analogy Breakup) model and Wave model are compared with experiments in order to describe droplet atomization process. The Watkins model and O'Rourke model are compared to simulate the spray wall impingement. As a result, It is found that the application of the Wave model has a good agreement with the experimental data in the case of high pressure injection. With regard to wall Impingement phenomena, it is found that the Watkins model is appropriate to the high temperature cylinder wall condition, while the O'Rourke model is appropriate to cold starting problem.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.1-7
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• 2007

The effect of injector geometries including the injection angle and number of nozzle holes on homogeneous charge compression ignition (HCCI) engine combustion has been investigated in an automotive-size single-cylinder diesel engine. The HCCI engine has advantages of simultaneous reduction of PM and NOx emissions by achieving the spatially homogenous distribution of diesel fuel and air mixture, which results in no fuel-rich zones and low combustion temperature. To make homogeneous mixture in a direct-injection diesel engine, the fuel is injected at early timing. The early injection guarantees long ignition delay period resulting in long mixing period to form a homogeneous mixture. The wall-impingement of the diesel spray is a serious problem in this type of application. The impingement occurs due to the low in-cylinder density and temperature as the spray penetrates too deep into the combustion chamber. A hole-type injector (5 holes) with smaller angle ($100^{\circ}$) than the conventional one ($150^{\circ}$) was applied to resolve this problem. The multi-hole injector (14 holes) was also tested to maximize the atomization of diesel fuel. The macroscopic spray structure was visualized in a spray chamber, and the spray penetration was analyzed. Moreover, the effect of injector geometries on the power output and exhaust gases was tested in a single-cylinder diesel engine. Results showed that the small injection angle minimizes the wall-impingement of diesel fuel that results in high power output and low PM emission. The multi-hole injector could not decrease the spray penetration at low in-cylinder pressure and temperature, but still showed the advantages in atomization and premixing.

• Advances in pediatric surgery
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• v.7 no.2
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• pp.142-146
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• 2001

Lymphangioma is a congenital malformation of the lymphatic system, commonly seen in the neck. Operation was the treatment of choice but it is difficult to resect the lymphangiomas completely. The aim of this study is to evaluate the result of intralesional injection of OK-432 as a treatment strategy of lymphangioma in children. Medical records of 51 cases of lymphangioma from March 1996 to February 2001 were reviewed retrospectively. Intralesional injection of 0.1mg OK-432 in 10ml normal saline was performed after the aspiration of as much fluid as possible. The location of the lesion was the face and neck in 26 patients, the chest wall in 14, the extremities in 9, and the abdominal wall in 2. The cystic type was present in 45 patients and the cavernous type in 6. Four postoperative recurrent cases were included. Fluid aspiration from the lesion was impossible in 5 patients. Development of fever after injection was observed in 27 patients and local inflammatory reaction was in 5 patients. There was no scar formation at injection sites. Complete shrinkage was observed in 20 patients, remarkable shrinkage in 23, slight shrinkage in 3, and no response in 5. Cystic type or aspiration-possible cases showed better outcome than cavernous type or aspiration-impossible cases. All of four recurrent cases after surgical excision showed at least remarkable shrinkage. These results indicate that intralesional injection of OK-432 is a safe and satisfactory treatment modality of lymphangiomas in children and might be considered as a treatment of choice, even in recurrent cases.

• Journal of Chest Surgery
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• v.19 no.1
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• pp.1-11
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• 1986

Using an experimental model of pulmonary hypertension, the effects of anticonstrictive drugs on the development of pulmonary vascular remodeling and right ventricular hypertrophy were studied. Male Sprague-Dawley rats weighing 200~250 gm were used. For the experimental model of pulmonary hypertension, a group of animal was given by a subcutaneous injection of monocrotaline on a dose of 20mg, 40mg, or 60mg per kg of body weight. After 4 weeks of injection, all animals were sacrificed. Another group of animal was given by a subcutaneous injection of monocrotaline in a dose of 40 mg per kg of body weight. The animals were sacrificed, in which they were kept alive for 1, 2, 3 and 4 weeks, respectively. For the effects of anticonstrictive drugs on the development of pulmonary vascular remodeling and right ventricular hypertrophy, the animals treated with monocrotaline were given daily by an intraperitoneal injection of phenoxybenzamine in a dose of 1.3mg/kg of body weight, and were given propranolol via their drinking water at a concentration of 400mg/liter. The animals were sacrificed after 4 weeks of administration. The hearts and lungs were examined histopathologically and morphometrically. The results obtained were summarized as follows: 1. The rats treated with monocrotaline showed an interstitial pneumonitis, medial thickening of the pulmonary small arteries and hypertrophy of the right ventricular wall. 2. The medial thickening of the pulmonary arteries in rats treated with monocrotaline was due to muscular hypertrophy and hyperplasia, and the right ventricular hypertrophy was due to hypertrophy of cardiac muscles. Both medial thickening of the pulmonary arteries and hypertrophy of right ventricular wall were more marked with time and with dose. 3. The daily intraperitoneal injection of phenoxybenzamine suppressed significantly the percentage medial thickness of pulmonary small arteries and the index of right ventricular hypertrophy in rats given a single subcutaneous injection of monocrotaline, but propranolol has shown no protective effect on the development of medial thickening of pulmonary arteries and right ventricular hypertrophy in treated with monocrotaline. The results described above suggested that monocrotaline is an alkaloid selectively inducing pulmonary hypertension and that a-adrenergic receptor is responsible for the pathogenesis of monocrotaline induced pulmonary hypertension in rat.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.221-238
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• 2004

Wall interactions of direct injection spray were investigated using laser-sheet imaging, shadowgraphy, wetted footprint and phase Doppler interferometry techniques. A narrow-cone high-pressure swirl injector is used to inject iso-octane fuel onto a plate, which has three different impact angles inside a pressurized chamber. Heated air and plate conditions were compared with unheated cases. Injection interval was also varied in the heated case to compare dry- and wet- wall impingement behaviors. High-speed macroscopic Mie-scattering images showed that presence of wall and air temperature has only minor effect on the bulk spray structure and penetration speed for the narrow-cone injector tested. The overall bulk motions of the spray plume and its spatial position at a given time are basically unaffected until a few millimeters before impacting the wall. The surface properties of the impact surface, such as the temperature, the presence of a preexisting liquid film also have a small effect on the amount of wetting or the wetted footprint; however, they have strong influence on what occurs just after impact or after a film is formed. The shadowgraph in particular shows that the plate temperature has a significant effect on vapor phase propagation. Generally, 10-20% faster horizontal vapor phase propagation is observed along the wall at elevated temperature condition. For impingement onto a preexisting film, more splash and evaporation were also observed. Contrary to some preconceptions, there is no significant splashing and droplet rebounding from surfaces that are interposed in the path of the DI gasoline spray, especially for the oblique impact angle cases. There also appears to be a dense spray front consists of large sac spray droplets in the oblique impact angle cases. The bulk of the spray is not impacted on the surface, but rather is deflected by it The microscopic details as depicted by phase Doppler measurements show that the outcome of the droplet impaction events can be significantly influenced. Only droplets at the spray front have high enough Weber numbers for wall impact to wet, splash or rebound. Using the sign of vertical velocity, the time-resolved downward droplets and upward droplets are compared. The Weber number of upward moving droplets, which seldom exceeds unity, also decreases as the impact angle decreases, as the droplets tend to impact less and move along the wall in the deflected spray plume.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2355-2363
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• 2002

The accompanying paper, Part 1, has presented the physical modeling and basic numerical analysis results of both the flow-induced and thermally-induced residual stress and birefringence in injection molded center gated disks. The present paper, Part II, has attempted to investigate the effects of various processing conditions of injection/compression molding process on the residual stress and birefringence. The birefringence is significantly affected by injection melt temperature, packing pressure and packing time. Birefringence in the shell layer increases as melt temperature gets lower. The inner peak of birefringence increases with packing time and packing pressure. On the other hand, packing pressure, packing time and mold wall temperature affect the thermally-induced residual stress rather significantly in the shell layer, but insignificantly in the core region. Injection/compression molding has been found to reduce the birefringence in comparison with the conventional injection molding process. In particular, mold closing velocity and initial opening thickness in the compression stage of injection/compression molding process have significant effect on the flow-induced birefringence, but not on tile thermal residual stress and the thermally induced birefringence.