• Radiation Oncology Journal
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• v.32 no.1
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• pp.31-42
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• 2014

Purpose: To evaluate the usefulness of positron emission tomography/computed tomography (PET/CT) for field modification during radiotherapy in esophageal cancer. Materials and Methods: We conducted a retrospective study on 33 patients that underwent chemoradiotherapy (CRT). Pathologic findings were squamous cell carcinoma in 32 patients and adenocarcinoma in 1 patient. All patients underwent PET/CT scans before and during CRT (after receiving 40 Gy and before a 20 Gy boost dose). Response evaluation was determined by PET/CT using metabolic tumor volume (MTV), total glycolytic activity (TGA), MTV ratio (rMTV) and TGA ratio (rTGA), or determined by CT. rMTV and rTGA were reduction ratio of MTV and TGA between before and during CRT, respectively. Results: Significant decreases in MTV ($MTV_{2.5}$: mean 70.09%, p < 0.001) and TGA ($TGAV_{2.5}$: mean 79.08%, p < 0.001) were found between before and during CRT. Median $rMTV_{2.5}$ was 0.299 (range, 0 to 0.98) and median $rTGAV_{2.5}$ was 0.209 (range, 0 to 0.92). During CRT, PET/CT detected newly developed distant metastasis in 1 patient, and this resulted in a treatment strategy change. At a median 4 months (range, 0 to 12 months) after completion of CRT, 8 patients (24.2%) achieved clinically complete response, 11 (33.3%) partial response, 5 (15.2%) stable disease, and 9 (27.3%) disease progression. $SUV_{max}$ (p = 0.029), $rMTV_{50%}$ (p = 0.016), $rMTV_{75%}$ (p = 0.023) on intra-treatment PET were found to correlate with complete clinical response. Conclusion: PET/CT during CRT can provide additional information useful for radiotherapy planning and offer the potential for tumor response evaluation during CRT. $rMTV_{50%}$ during CRT was found to be a useful predictor of clinical response.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.541-547
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• 2010

The rigorous validation of the accuracy of metamodels is an important topic in research on metamodel techniques. Although a leave-k-out cross-validation technique involves a considerably high computational cost, it cannot be used to measure the fidelity of metamodels. Recently, the mean$_0$ validation technique has been proposed to quantitatively determine the accuracy of metamodels. However, the use of mean$_0$ validation criterion may lead to premature termination of a sampling process even if the kriging model is inaccurate. In this study, we propose a new validation technique based on the mean and variance of the response evaluated when sequential sampling method, such as maximum entropy sampling, is used. The proposed validation technique is more efficient and accurate than the leave-k-out cross-validation technique, because instead of performing numerical integration, the kriging model is explicitly integrated to accurately evaluate the mean and variance of the response evaluated. The error in the proposed validation technique resembles a root mean squared error, thus it can be used to determine a stop criterion for sequential sampling of metamodels.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.26 no.4
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• pp.273-278
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• 2015

Objectives : We retrospectively investigated the efficacy and tolerability of risperidone monotherapy in subjects with autism spectrum disorder (ASD). In addition, we did mixed effect model analysis of the effects of risperidone in patients with ASDs naturalistically treated in a routine clinical setting to determine whether the clinical effects were maintained and the side effects were tolerable. Methods : This retrospective study assessed children and adolescents with ASD, who were on risperidone monotherapy from July 2010 to July 2011 at the Child and Adolescent ASD Clinic at Seoul National Hospital. Outcome measures included the Clinical Global Impression-Severity of Illness (CGI-S) and the CGI-Improvement (CGI-I) scales along with other clinical indices: dosage, target symptoms, and side effects. Results : The mean dose of risperidone in 47 children and adolescents with ASD (40 males, 7 females; age range 5-19 years) who were on risperidone monotherapy was $1.6{\pm}0.8mg/day$, and the mean duration of the treatment period was $20.2{\pm}17.3months$. Aggressive behavior, stereotypic behavior, irritability, and self-injurious behavior were the most frequent target symptoms of risperidone. The most common side effects were weight gain followed by somnolence and extrapyramidal symptoms. In a mixed effects model analysis of CGI-I scores, the mean CGI-I score at the 1 month follow-up was significantly different from the mean CGI-I score of the 3-month follow-up (p=.046), and the CGI-I scores were equally maintained over 3 to 48 months [F(6, 28.9)=4.393, p=.003]. Of the 47 patients, 33 patients (70.2%) were identified as the response group, showing an end point CGI-I rating of 3 or under and having continued risperidone treatment for at least 6 months. The baseline CGI-S score showed significant association with clinical response to risperidone (p=.005), the mean baseline CGI-S was higher in the response group compared to the non-response group. Conclusion : In this study, clinical improvement of risperidone stabilized around 3 months and was equally maintained up to 48 months with tolerable side effects, supporting maintenance of risperidone treatment in children and adolescents with ASDs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7061-7070
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• 2015

Multi-Response Surface Optimization aims at finding the optimal setting of input variables considering multiple responses simultaneously. The Weighted Mean Squared Error (WMSE) minimization approach, which imposes a different weight on the two components of mean squared error, squared bias and variance, first obtains WMSE for each response and then minimizes all the WMSEs at once. Most of the methods proposed for the WMSE minimization approach to date are classified into the prior preference articulation approach, which requires that a decision maker (DM) provides his/her preference information a priori. However, it is quite difficult for the DM to provide such information in advance, because he/she cannot experience the relationships or conflicts among the responses. To overcome this limitation, this paper proposes a posterior preference articulation method to the WMSE minimization approach. The proposed method first generates all (or most) of the nondominated solutions without the DM's preference information. Then, the DM selects the best one from the set of nondominated solutions a posteriori. Its advantage is that it provides an opportunity for the DM to understand the tradeoffs in the entire set of nondominated solutions and effectively obtains the most preferred solution suitable for his/her preference structure.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.317-323
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• 2000

Objective : To evaluate the role of stereotactic LINAC radiosurgery in treatment of meningiomas, the authors retrospectively analyzed the result of radiosurgery in our institute. Method: During last ten years, twenty patients underwent stereotactic LINAC radiosurgery(LINAC SRS) for meningiomas. The mean age of the patients was 51 years(22-78 years). The most common tumor location for radiosurgery was parasagittal, sphenoid wing and tentorial area. With regards to indications of radiosurgery for meningiomas, LINAC radiosurgery was done for primary treatment in six patients, for postoperative residual tumors in eleven patients, for postoperative regrowth in three patients. Mean tumor volume was $5.14cm^3$($0.28-15.1cm^3$), mean field diameter was 2.01cm(1.2-3cm). The mean marginal dose was 20.55Gy(13-30Gy). The follow-up evaluation was done annually with radiologic findings and clinical status. The mean follow-up period was 46.8(24-120) months. Result : In the radiologic response, the tumor volume was reduced in five(25%) of twenty patients, fourteen showed arrested growth(70%), but one patient showed increased growth(5%). In the clinical response, nine patients improved clinically(45%), ten patients was stable(50%) and one patient worsened during follow-up period. With regards to correlation with radiologic and clinical response, in nineteen patients who showed radiologic response to radiosurgery(decreased and arrested growth after radiosurgery), nine patients(47.4%) improved and ten patients (52.6%) showed no change, one patient(5%) had symptomatic radiation necrosis at four years after SRS, which needed craniotomy. Conclusion : The overall control rate of meningiomas with LINAC radiosurgery was 95% in radiologic follow up and 95% clinically. The radiation complication rate was 5%. These results indicate that LINAC radiosurgery can be considered as safe and effective method for meningiomas.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.77-86
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• 2020

In this study, the importance of implied strength correction for shallow depths at a region of moderate to low seismicity with primary focus on its effect upon site natural period and mean period of the ground motion is investigated. In addition to the most commonly used Modified Kondner-Zelasko (MKZ) model, this paper uses a quadratic/hyperbolic (GQ/H) model that can capture the stress - strain response at large strains as well as small strain stiffness dependence. A total of six site profiles by downhole tests are used and 1D site response analyses are performed using three input motions with contrasting mean periods. The difference between non-corrected and corrected analyses is conditional on the site period as well as mean ground motion period. The effect of periods is analyzed by correlating them with the effective peak ground acceleration, maximum shear strains and amplification factors. The comparative study reveals that the difference is more prominent in soft sites with long site periods. Insignificant differences are observed when soil profiles are subjected to ground motion with very short mean period.

• The Korean Journal of Pain
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• v.4 no.2
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• pp.142-146
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• 1991

One hundred twenty patients with acute and chronic pain treated by a low power laser were divided into several groups by their pathology and evaluated according to their response rate to laser therapy through a follow-up study. 1) The ages of the patients were between the early twenties and late forties (71.7%), and there was no differences between sexes. 2) The spinal pathology group was the most common(52.5%) and the articular pathology group occupied next (14.2%). 3) The average duration of Laser therapy was about 20 days and response to the therapy appeared about the eighth day. 4) The response to the therapy in the spinal pathology group appeared about the eighth day and the average duration of therapy was about 18 days. 5) The response to the therapy in the articular pathology group appeared about the eighth day and the average duration of therapy was about 28 days. 6) The response rate of the spinal pathology group was 81.0%, and remarkable symptom relief was noted when compaired to a 58.7% response rate in the control group, 7) The response rate of the articular pathology group was 82.4%, which was similar to the control group. 8) The response rate of the miscellaneous group was 87.0%, and remarkable symptom relief was noted when compaired to a 66.7A response rate in the control group. 9) The mean response rate of all patients treated by a low power laser was 82.5% and that of the control group was 70.5%. Laser therary proved to be an effective treatment modality for acute and chronic pain.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.259-270
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• 2017

The stochastic vibration response of the sandwich beam with the nonlinear adjustable visco-elastomer core and supported mass under stochastic support motion excitations is studied. The nonlinear dynamic properties of the visco-elastomer core are considered. The nonlinear partial differential equations for the horizontal and vertical coupling motions of the sandwich beam are derived. An analytical solution method for the stochastic vibration response of the nonlinear sandwich beam is developed. The nonlinear partial differential equations are converted into the nonlinear ordinary differential equations representing the nonlinear stochastic multi-degree-of-freedom system by using the Galerkin method. The nonlinear stochastic system is converted further into the equivalent quasi-linear system by using the statistic linearization method. The frequency-response function, response spectral density and mean square response expressions of the nonlinear sandwich beam are obtained. Numerical results are given to illustrate new stochastic vibration response characteristics and response reduction capability of the sandwich beam with the nonlinear visco-elastomer core and supported mass under stochastic support motion excitations. The influences of geometric and physical parameters on the stochastic response of the nonlinear sandwich beam are discussed, and the numerical results of the nonlinear sandwich beam are compared with those of the sandwich beam with linear visco-elastomer core.

• Anxiety and mood
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• v.11 no.1
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• pp.33-37
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• 2015

Objective : Impaired response inhibition has been suggested to play an important role in the pathophysiology of obsessive-compulsive disorder (OCD). The aim of this study was to evaluate the response inhibition in patients with OCD, by using the Go/NoGo paradigm, and to better understand its associations with clinical symptoms. Methods : The participants included 63 OCD patients and 80 healthy volunteers matched in age and sex. response inhibition was evaluated using computerized Go/NoGo task, in which their commission error rates, omission error rates, and mean response times were measured. The severity of clinical symptoms in the OCD patients was assessed using Montgomery-Asberg Depression Scale and Yale-Brown Obsessive Compulsive Scale. Result : OCD patients showed significantly impaired inhibition and higher omission errors rates despite their slower response time, compared to normal controls. Clinical symptoms were not correlated with commission errors and omission errors. Conclusion : The present results indicate that impairment in response inhibition may play a critical role in the pathophysiology of OCD as a trait. These findings suggest that deficit of response inhibition may contribute to developing and maintaining clinical symptoms such as compelling need to repeat certain actions in patients with OCD.

• The Korean Journal of Pain
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• v.2 no.1
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• pp.30-35
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• 1989

Two hundred patients with acute and chronic pain were treated with a low power laser and 115 patients among them were divided into several groups by their pathology and evaluated their response rate to the laser therapy was evaluated through follow-up study. 1) The ages of patients were between the early twenties and late sixties, and there was no differences between sexes. 2) Degenerative spondylosis and chronic lumbar sprain were the most common diseases among those patients. 3) The average duration of therapy was about 16 days and response to the therapy appeared from the fourth day of laser therapy. 4) Acute lumbar sprain and acute spinal compression fracture showed rapid response to laser therapy. 5) The spinal pathology group was the most common at 37.5% of cases and the response rate to laser therapy was the lowest at 58.7%. 6) The articular pathology group occupied 24.6% and the response rate was the highest at 81.3%. 7). The response rate of the posttraumatic and postsurgical pathology group was 76.5%. 8) The response rate of the tendinous and sports pathology group was 75%. 9) The response rate of the miscellaneous group was 66.7%. 10) The mean response rate of all patients was 71.6%.