• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.3
• /
• pp.46-52
• /
• 2018

A simple Crocco's $n-{\tau}$ time delay model and linear analysis of fluid flow coupled with acoustics are combined to investigate the high frequency combustion instability in the combustion chamber of LOX/hydrocarbon engines. The partial differential equation of the velocity potential is separated into ordinary differential equations, and eigenvalues that correspond to tangential resonance modes in the cylindrical chamber are determined. A general solution is obtained by solving the differential equation in the axial direction, and boundary conditions at the injector face and nozzle entrance are applied in order to calculate the chamber admittance. Frequency analysis of the transfer function is used to evaluate the stability of system. Stability margin is determined from the system gain and phase angle for the desired frequency range of 1T mode. The chamber model with variable baffle length and configurations are also considered in order to enhance the 1T mode stability of the combustion chamber.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.6 no.2
• /
• pp.139-149
• /
• 1994

In this paper, a finite element technique is applied to the prediction of the wave resonance phenomena in harbors. The mild-slope equation is used with a partial reflection boundary condition introduced to model the energy dissipating effects on the solid boundary. For an efficient modeling of the radiation condition at infinity, a new infinite element is developed. The shape function of the infinite element is derived from the asymptotic behavior of the first kind of the Hankel's function in the analytical boundary series solutions. For the computational efficiency, the system matrices of the element are constructed by performing the relevant integrations in the infinite direction analytically. Comparisons with the results from experiments and other solution methods show that the present model gives fairly good results. Numerical experiments are also carried out to determine the proper distance to the infinite elements from the mouth of the halter, which directly affect the accuracy and efficiency of the solution.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.8
• /
• pp.2455-2460
• /
• 2013

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the nucleophilic displacement reactions of 4-nitrophenyl X-substituted-cinnamates (4a-4e) and Y-substituted-phenyl cinnamates (5a-5e) with Z-substituted-phenoxide anions in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. The Hammett plot for the reactions of 4a-4e with 4-chlorophenoxide (4-$ClPhO^-$) consists of two intersecting straight lines, which might be taken as a change in the rate-determining step (RDS). However, it has been concluded that the nonlinear Hammett plot is not due to a change in the RDS but is caused by stabilization of the ground state of substrates possessing an electron-withdrawing group in the cinnamoyl moiety through resonance interactions, since the Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}X=0.89$ and r = 0.58. The Br${\o}$nsted-type plot for the reactions of 4-nitrophenyl cinnamate (4c) with Z-substituted-phenoxides is linear with ${\beta}_{nuc}=0.76$. The Br${\o}$nsted-type plot for the reactions of Y-substituted-phenyl cinnamates (5a-5d) with 4-chlorophenoxides (4-$ClPhO^-$) is also linear with ${\beta}_{lg}=-0.72$. The Hammett plot correlated with ${\sigma}^-$ constants for the reactions of 5a-5d results in a much better linear correlation than that correlated with ${\sigma}^o$ constants, indicating that a partial negative charge develops on the O atom of the leaving aryloxide. Thus, the reactions have been concluded to proceed through a concerted mechanism.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.12a
• /
• pp.27-32
• /
• 2006

In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. Due to this generation, the extinction of atoms in a metastable state occurred through collision, ionization, and excitation between plasma particles. The density and distribution of the metastable state depended on the energy and density of plasma particles, intensely. This highlights the importance of measuring density distribution in plasma electric discharge mechanism study. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength change, and also confirmed that the largest fluorcscent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1{\rightarrow}6^3P_2$) were larger than 404.8nm ($6^3S_1{\rightarrow}6^3P_2$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the LIF signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.sup2
• /
• pp.352-355
• /
• 2001

The authors report two cases of familial hemifacial spasm according to the clinical and three dimensional shortrange magnetic resonance angiography(3D-SRMRA) findings. In the family of the first case, there were five patient's with acquired hemifacial spasm in successive generations. Three male and two female patients in successive generations of the same family developed acquired hemifacial spasm. Four patients were on the left side and one was on the right side. In the family of the second case, there were three patient's with acquired hemifacial spasm in successive generations. Two brothers developed left-sided hemifacial spasm. 3D-SRMRA finding of the probands demonstrated that both anterior inferior cerebellar artery in first case and anterior inferior cerebellar artery & vertebral artery in second case offend the 7th cranial nerve respectively. The presence of familial clustering of these rare disorders suggest an underlying genetic predisposition. All family pedigrees suggest that a pattern of autosomal-dominant inheritance with partial penetrance.

• The Journal of Internal Korean Medicine
• /
• v.43 no.4
• /
• pp.751-760
• /
• 2022

Objective: To show a decrease in tumor recurrence and improvement in quality of life in patients with recurrent cervical cancer. Method: A 58-year-old female patient diagnosed with recurrent cervical cancer in February 2021 was treated for 14 months with integrative cancer treatment (ICT) to decrease the tumor size and improve chemotherapy-induced peripheral neuropathy (CIPN) and nausea. The patient underwent chemotherapy or concomitant chemoradiation therapy (CCRT) with ICT. Radiologic outcomes were assessed by abdomen & pelvis computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) based on the Response Evaluation Criteria in Solid Tumors (RECIST) protocol. Clinical outcomes were assessed by the National Cancer Institute Common Terminology Criteria for Adverse Event (NCI-CTCAE), Eastern Cooperative Oncology Group (ECOG), and a numeric rating scale (NRS). Result: During the 14 months of treatment, the size and metabolic activity of the recurrent tumor decreased and underwent partial remission based on RECIST. The NRS scores for CIPN and nausea were improved, and the ECOG score improved from grade 2 to 1. No serious side effects of grade 3 or higher were noted on the NCI-CTCAE test. Conclusion: This case suggests that ICT may have a synergetic effect with chemotherapy or radiotherapy for recurrent cervical cancer.

• Journal of Convergence for Information Technology
• /
• v.12 no.2
• /
• pp.142-148
• /
• 2022

In this paper, the weight reduction design of the yaw gearbox for wind turbine was performed through the finite element analysis method, and the stability was checked by performing the critical speed analysis. The weight reduction product can improve engine efficiency, save parts materials, and earn economic benefits. The yaw gearbox is lightweighted with the goal of achieving a safety rate of 1.3 or higher for wind turbine as indicated by IEC61400-1. In order to reduce the weight of the carrier, a topology optimization method was performed. The safety factor was verified by performing finite element analysis on the carrier. In addition, the housing and carrier were modeled using the finite element method, and the gear train was modeled using MASTA. For the yaw gearbox, the housing and carrier FE model and the gear train model were connected by the partial structural synthesis method to perform the rotational vibration analysis. Vibration excitation sources are mass unbalance and gear mesh frrequemcy, and as a result of the critical speed analysis, it was found that there was no resonance within the operating speed range.

• Clinical Pain
• /
• v.19 no.2
• /
• pp.120-123
• /
• 2020

Rapidly destructive arthrosis is a rare syndrome characterized by narrowing of the joint space and rapid joint destruction within 6~12 months. A 62-year-old woman with anaplastic lymphoma kinase rearranged non-small-cell lung cancer presented with both knee pain and varus deformity. She was treated with crizotinib 500 mg/day for more than 2 years, with partial tumor response. Initial plain radiography showed Kellgren and Lawrence (K-L) grade 1. After 10 months, varus deformity was worsened and plain radiography aggravated to K-L grade 4 despite conservative treatment including activity modification. Diffuse synovitis with massive joint effusion and destruction of anterior cruciate ligament, medial meniscus, medial collateral ligament, and lateral collateral ligament were shown in magnetic resonance imaging. The patient was diagnosed with rapidly destructive arthrosis of knee and underwent a both total knee arthroplasty.

• The Journal of Internal Korean Medicine
• /
• v.43 no.5
• /
• pp.838-853
• /
• 2022

Objectives: The purpose of this study is to report the case of a patient with recurrent L858R mutation non-small-cell lung cancer with brain metastases treated with erlotinib and traditional Korean medicine after gefitinib failure. Methods: The patient was treated with erlotinib beginning in November 2021, and gamma knife surgery was performed on November 8, 2021. The dose of erlotinib was 150 mg/day every four weeks. At the same time, the patient was treated with traditional Korean medicine. Tumor size and cerebral edema were measured using computed tomography and magnetic resonance imaging, respectively. Adverse events were evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. Results: After treatment with erlotinib and traditional Korean medicine for six months, the extent of the growing nodule in the right upper lobe decreased during the first three months and remained stable for the following three months. Peritumoral edema showed an increase three months after gamma knife surgery, but partial improvement of cerebral edema was confirmed with additional traditional Korean medicine six months after gamma knife surgery. The symptoms of discomfort and physical activity gradually improved. Conclusions: This case study suggests that the combination of EGFR-TKI and traditional Korean medicine may contribute to a reduction in tumor size and cerebral edema while improving quality of life.

• Journal of the Korean Orthopaedic Association
• /
• v.55 no.3
• /
• pp.276-280
• /
• 2020

A 49-year-old male was found unconscious at his accommodation and visited the emergency room. He was on antipsychotic and antidepressant drugs (vortioxetine hydrobromide, mirtazapine, sertraline hydrochloride, quetiapine, and alprazolam) for schizophrenia and major depression. At the time of discovery there were signs of overdose of the drugs around the patient. A physical examination revealed, pain, pallor, and edema in the left buttocks and lateral thigh. Active ankle movements below the left ankle were not possible and sensations in the tibia and peroneal nerves were lost. The pressure in the buttock compartment was measured at 42 mmHg. Magnetic resonance imaging revealed edema and high intensity signals in the left hip muscles and surrounding soft tissue. An emergency fasciotomy was performed and partial restoration of the lower extremity sensation and muscle strength were achieved after 24 hours.