• Korean Journal of Radiology
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• 제22권6호
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• pp.922-930
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• 2021

Objective: It is uncertain why a b-value range of 1500-2000 s/mm² is optimal. This study was aimed at qualitatively and quantitatively analyzing the optimal b-value range of synthetic diffusion-weighted imaging (sDWI) for evaluating prostatic index lesions. Materials and Methods: This retrospective study included 92 patients who underwent DWI and targeted biopsy for magnetic resonance imaging (MRI)-suggested index lesions. We generated sDWI at a b-value range of 1000-3000 s/mm² using dedicated software and true DWI data at b-values of 0, 100, and 1000 s/mm². We hypothesized that lesion conspicuity would be best when the background (i.e., MRI-suggested benign prostatic [bP] and periprostatic [pP] regions) signal intensity (SI) is suppressed and becomes homogeneous. To prove this hypothesis, we performed both qualitative and quantitative analyses. For qualitative analysis, two independent readers analyzed the b-value showing the best visual conspicuity of an MRI-suggested index lesion. For quantitative analysis, the readers assessed the b-value showing the same bP and pP region SI. The 95% confidence interval (CI) or interquartile range of qualitatively and quantitatively selected optimal b-values was assessed, and the mean difference between qualitatively and quantitatively selected b-values was investigated. Results: The 95% CIs of optimal b-values from qualitative and quantitative analyses were 1761-1805 s/mm² and 1640-1771 s/mm² (median, 1790 s/mm² vs. 1705 s/mm²; p = 0.003) for reader 1, and 1835-1895 s/mm² and 1705-1841 s/mm² (median, 1872 s/mm² vs. 1763 s/mm²; p = 0.022) for reader 2, respectively. Interquartile ranges of qualitatively and quantitatively selected optimal b-values were 1735-1873 s/mm² and 1573-1867 s/mm² for reader 1, and 1775-1945 s/mm² and 1591-1955 s/mm² for reader 2, respectively. Bland-Altman plots consistently demonstrated a mean difference of less than 100 s/mm² between qualitatively and quantitatively selected optimal b-values. Conclusion: b-value range showing a homogeneous background signal may be optimal for evaluating prostatic index lesions on sDWI. Our qualitative and quantitative data consistently recommend b-values of 1500-2000 s/mm².

• Korean Journal of Radiology
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• 제22권4호
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• pp.502-512
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• 2021

Objective: To objectively and subjectively assess and compare the characteristics of monoenergetic images [MEI (+)] and polyenergetic images (PEI) acquired by dual-energy CT (DECT) of patients with breast cancer. Materials and Methods: This retrospective study evaluated the images and data of 42 patients with breast cancer who had undergone dual-phase contrast-enhanced DECT from June to September 2019. One standard PEI, five MEI (+) in 10-kiloelectron volt (keV) intervals (range, 40-80 keV), iodine density (ID) maps, iodine overlay images, and Z effective (Z_eff) maps were reconstructed. The contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) were calculated. Multiple quantitative parameters of the malignant breast lesions were compared between the arterial and the venous phase images. Two readers independently assessed lesion conspicuity and performed a morphology analysis. Results: Low keV MEI (+) at 40-50 keV showed increased CNR and SNR_{breast lesion} compared with PEI, especially in the venous phase ([CNR: 40 keV, 20.10; 50 keV, 14.45; vs. PEI, 7.27; p < 0.001], [SNR_{breast lesion}: 40 keV, 21.01; 50 keV, 16.28; vs. PEI, 10.77; p < 0.001]). Multiple quantitative DECT parameters of malignant breast lesions were higher in the venous phase images than in the arterial phase images (p < 0.001). MEI (+) at 40 keV, ID, and Z_eff reconstructions yielded the highest Likert scores for lesion conspicuity. The conspicuity of the mass margin and the visual enhancement were significantly better in 40-keV MEI (+) than in the PEI (p = 0.022, p = 0.033, respectively). Conclusion: Compared with PEI, MEI (+) reconstructions at low keV in the venous phase acquired by DECT improved the objective and subjective assessment of lesion conspicuity in patients with malignant breast lesions. MEI (+) reconstruction acquired by DECT may be helpful for the preoperative evaluation of breast cancer.

• 한국조경학회지
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• 제52권2호
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• pp.39-50
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• 2024

색채는 중요한 시각적 요소로서 도시 이미지와 사람들의 인식 형성에 중요한 영향을 미친다. 도시환경에서 색채를 정량적으로 분석하는 작업은 복잡한 과정을 필요로 하여 과거에는 실행하기가 어려웠다. 그러나 최근 머신 러닝 기술의 급속한 발전으로 관광객이 공유한 사진을 이용하여 도시 색채를 분석하는 것이 가능해졌다. 본 연구는 중국의 인기 관광지인 대리시를 사례로 선정하여 관광객이 공유한 대리시의 사진을 수집하였으며, 머신 러닝 기술을 결합하여 대규모 도시 색채를 측정하는 방법을 탐색하였다. 구체적으로는 먼저 DeepLabv3+ 모델을 사용하여 ADE20k 데이터 셋을 기반으로 관광객이 공유한 사진의 의미 분할을 수행하여 사진에서 인공 요소를 분리했다. 다음으로 K-means 클러스터링 알고리즘을 사용하여 대리시의 인공 요소의 주요 색상을 추출하고, 이러한 색상 간의 상관관계를 분석하기 위해 인접 매트릭스를 구축했다. 연구 결과에 따르면 대리시의 인공 요소의 주요 색상은 주황-회색이 가장 높은 비율을 차지한다. 또한, 회색 계열의 색상이 다른 색상과 자주 조합되어 사용되는 경향이 있다. 분석에 따르면 대리시의 인공 요소의 색채 특성은 지역의 민족 문화와 불교 문화의 영향을 받는 것으로 나타났다. 본 연구는 색채 분석을 위한 새로운 접근 방법을 제공하며, 연구 결과는 대리시가 관광객의 기대에 부합하는 도시 색채 이미지를 형성하는 데 도움이 될 뿐만 아니라 향후 대리시의 색채 계획을 위한 참고 자료를 제공하고자 한다.

• Korean Journal of Radiology
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• 제24권6호
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• pp.498-511
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• 2023

Objective: To evaluate the diagnostic performance of chest computed tomography (CT)-based qualitative and radiomics models for predicting residual axillary nodal metastasis after neoadjuvant chemotherapy (NAC) for patients with clinically node-positive breast cancer. Materials and Methods: This retrospective study included 226 women (mean age, 51.4 years) with clinically node-positive breast cancer treated with NAC followed by surgery between January 2015 and July 2021. Patients were randomly divided into the training and test sets (4:1 ratio). The following predictive models were built: a qualitative CT feature model using logistic regression based on qualitative imaging features of axillary nodes from the pooled data obtained using the visual interpretations of three radiologists; three radiomics models using radiomics features from three (intranodal, perinodal, and combined) different regions of interest (ROIs) delineated on pre-NAC CT and post-NAC CT using a gradient-boosting classifier; and fusion models integrating clinicopathologic factors with the qualitative CT feature model (referred to as clinical-qualitative CT feature models) or with the combined ROI radiomics model (referred to as clinical-radiomics models). The area under the curve (AUC) was used to assess and compare the model performance. Results: Clinical N stage, biological subtype, and primary tumor response indicated by imaging were associated with residual nodal metastasis during the multivariable analysis (all P < 0.05). The AUCs of the qualitative CT feature model and radiomics models (intranodal, perinodal, and combined ROI models) according to post-NAC CT were 0.642, 0.812, 0.762, and 0.832, respectively. The AUCs of the clinical-qualitative CT feature model and clinical-radiomics model according to post-NAC CT were 0.740 and 0.866, respectively. Conclusion: CT-based predictive models showed good diagnostic performance for predicting residual nodal metastasis after NAC. Quantitative radiomics analysis may provide a higher level of performance than qualitative CT features models. Larger multicenter studies should be conducted to confirm their performance.

• Korean Journal of Radiology
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• 제23권9호
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• pp.901-910
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• 2022

Objective: This study aimed to assess the technical feasibility, efficacy, and safety of the safe triangular working zone (STWZ) approach applied in percutaneous vertebroplasty (PV) for spinal metastases involving the posterior part of the vertebral body. Materials and Methods: We prospectively enrolled 87 patients who underwent PV for spinal metastasis involving the posterior part of the vertebral body, with or without the STWZ approach, from January 2019 to April 2022. Forty-nine patients (27 females and 22 males; mean age ± standard deviation [SD], 57.2 ± 11.6 years; age range, 31-76 years) were included in group A (with STWZ approach), accounting for 54 vertebrae. Thirty-eight patients (18 females and 20 males; 59.1 ± 10.9 years; 29-81 years) were included in group B (without STWZ approach), accounting for 57 vertebrae. Patient demographics, procedure-related variables, and pain relief as assessed using the visual analog scale (VAS) were collected at different time points. Tumor recurrence in the vertebrae after PV was analyzed using Kaplan-Meier curves. Results: The STWZ approach was successful from T1 to L5 without severe complications. Cement filling was satisfactory in 47/54 (87.0%) and 25/57 (43.9%) vertebrae in groups A and B, respectively (p < 0.001). Cement leakage was not significantly different between groups A and B (p = 1.000). Mean VAS score ± SD before and 1 week and 1, 3, 6, 9, and 12 months after PV were 7.6 ± 1.8, 4.2 ± 2.0, 2.7 ± 1.9, 1.9 ± 1.5, 1.7 ± 1.4, 1.7 ± 1.1, and 1.6 ± 1.3, respectively, in group A and 7.2 ± 1.7, 4.0 ± 1.3, 3.4 ± 1.6, 2.4 ± 1.2, 1.8 ± 1.0, 1.4 ± 0.5, and 1.7 ± 0.9, respectively, in group B. Kaplan-Meier analysis showed a lower tumor recurrence rate in group A than in group B (p = 0.001). Conclusion: The STWZ approach may represent a new, safe, alternative/auxiliary approach to target the posterior part of the vertebral body in the PV for spinal metastases.

• Korean Journal of Radiology
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• 제23권10호
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• pp.949-958
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• 2022

Objective: To investigate the feasibility of using a deep learning-based analysis of auscultation data to predict significant stenosis of arteriovenous fistulas (AVF) in patients undergoing hemodialysis requiring percutaneous transluminal angioplasty (PTA). Materials and Methods: Forty patients (24 male and 16 female; median age, 62.5 years) with dysfunctional native AVF were prospectively recruited. Digital sounds from the AVF shunt were recorded using a wireless electronic stethoscope before (pre-PTA) and after PTA (post-PTA), and the audio files were subsequently converted to mel spectrograms, which were used to construct various deep convolutional neural network (DCNN) models (DenseNet201, EfficientNetB5, and ResNet50). The performance of these models for diagnosing ≥ 50% AVF stenosis was assessed and compared. The ground truth for the presence of ≥ 50% AVF stenosis was obtained using digital subtraction angiography. Gradient-weighted class activation mapping (Grad-CAM) was used to produce visual explanations for DCNN model decisions. Results: Eighty audio files were obtained from the 40 recruited patients and pooled for the study. Mel spectrograms of "pre-PTA" shunt sounds showed patterns corresponding to abnormal high-pitched bruits with systolic accentuation observed in patients with stenotic AVF. The ResNet50 and EfficientNetB5 models yielded an area under the receiver operating characteristic curve of 0.99 and 0.98, respectively, at optimized epochs for predicting ≥ 50% AVF stenosis. However, Grad-CAM heatmaps revealed that only ResNet50 highlighted areas relevant to AVF stenosis in the mel spectrogram. Conclusion: Mel spectrogram-based DCNN models, particularly ResNet50, successfully predicted the presence of significant AVF stenosis requiring PTA in this feasibility study and may potentially be used in AVF surveillance.

• Korean Journal of Radiology
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• 제21권7호
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• pp.812-828
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• 2020

Objective: To provide an evidence-based guide for the MRI interpretation of complete tumor response after neoadjuvant chemoradiation therapy (CRT) for rectal cancer using visual assessment on T2-weighted imaging (T2) and diffusion-weighted imaging (DWI). Materials and Methods: PubMed MEDLINE, EMBASE, and Cochrane Library were searched on November 28, 2019 to identify articles on the following issues: 1) sensitivity and specificity of T2 or DWI for diagnosing pathologic complete response (pCR) and the criteria for MRI diagnosis; 2) MRI alone vs. MRI combined with other test(s) in sensitivity and specificity for pCR; and 3) tests to select patients for the watch-and-wait management. Eligible articles were selected according to meticulous criteria and were synthesized. Results: Of 1615 article candidates, 55 eligible articles (for all three issues combined) were identified. Combined T2 and DWI performed better than T2 alone, with a meta-analytic summary sensitivity of 0.62 (95% confidence interval [CI], 0.43-0.77; I² = 80.60) and summary specificity of 0.89 (95% CI, 0.80-0.94; I² = 92.61) for diagnosing pCR. The criteria for the complete response on T2 in most studies had the commonality of remarkable tumor decrease to the absence of mass-like or nodular intermediate signal, although somewhat varied, as follows: (near) normalization of the wall; regular, thin, hypointense scar in the luminal side with (near) normal-appearance or homogeneous intermediate signal in the underlying wall; and hypointense thickening of the wall. The criteria on DWI were the absence of a hyperintense signal at high b-value (≥ 800 sec/mm²) in most studies. The specific algorithm to combine T2 and DWI was obscure in half of the studies. MRI combined with endoscopy was the most utilized means to select patients for the watch-and-wait management despite a lack of strong evidence to guide and support a multi-test approach. Conclusion: This systematic review and meta-analysis provide an evidence-based practical guide for MRI assessment of complete tumor response after CRT for rectal cancer.

• 핵의학기술
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• 제15권2호
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• pp.65-71
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• 2011

근래의 심근 관류 SPECT를 위한 검사 장비는 진단의 정확도가 높아졌을 뿐만 아니라 검사 시간을 단축함으로써 환자의 편의성을 높이고 움직임에 대한 artifact를 줄이는 방향으로 발전되고 있다. 본 연구에서는 기존의 심근 관류 SPECT와 비교하여 IQ SPECT에 맞는 protocol을 design 하고 IQ SPECT의 특성과 유용성에 대하여 알아 보고자 하였다. Simens사의 Symbia T6 SPECT/CT를 이용하여 LEHR collimator와 Multiple confocal collimator에 대하여 acrylic dish에 $^{99m}Tc$ 37MBq을 넣고 5 cm, 10 cm, 20 cm, 30 cm, 40 cm 거리에서 각각 sensitivity ($cpm/{\mu}Ci$)를 측정 하였다. 그리고 Sensitivity 측정 결과를 바탕으로 기존의 일반적인 심근관류 SPECT를 기준으로 IQ SPECT protocol을 design 후 Anthropomorphic torso phantom을 사용하여 심근 관류 SPECT를 시행하여 비교하고, LEHR collimator의 영상 재구성에 따른 FWHM 비교를 위해 $^{99m}Tc$ Line source를 이용하여 기존의 심근 관류 SPECT의 재구성법인 FBP법과 IQ SPECT의 3D OSEM법에 대하여 알고리즘만 변화시켜 FWHM을 측정 비교하였다. Collimator senstivity 측정 결과 IQ SPECT의 multiple confocal collimator의 sensitivity가 LEHR collimator와 비교하여 30 cm 거리에서 sensitivity가 약 4배 정도 더 많아짐을 알 수 있었다. Sensitivity 결과를 바탕으로 IQ SPECT의 기하학적 특성에 맞게 심근 관류 SPECT protocol을 design 하여 phantom 실험을 시행한 결과 기존에 비해 검사시간을 1/4로 단축할 수 있었으며, LEHR collimator를 사용하여 SPECT 검사 후 FBP법과 3D OSEM 법의 재구성 알고리즘에 따른 FWHM 비교에서는 3D OSEM법에서 FWHM이 2배 정도 향상된 결과를 얻었다. 본 연구를 통해 IQ SPECT는 심근관류 SPECT에서 Multiple confocal collimator를 사용하여 감도를 향상시키고 심장에 특화된 기하학적인 영상 획득 방식과 영상 재구성 방법을 통하여 검사 시간을 단축하고 영상의 화질 개선에 도움을 준다. 이로 인해 환자는 전보다 더욱 편안하고 정확한 검사를 수행 할 수 있을 것이며, 추가적으로 더 많은 임상 자료를 통한 연구가 필요할 것이다.

• 한국의류학회지
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• 제31권12호
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• pp.1761-1771
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• 2007

시각적 효과를 내기 위해서 혹은 상징적 연출효과를 기대해서이던 간에 무대의상 제작에 있어 인위적 과장은 무대 위의 연출을 돋보이게 하는 중요한 표현 기술 중 하나이다. 본 연구의 목적은 무대의상의 역사를 공연예술사에 나타난 다양한 무대연출의 극적 효과를 보다 잘 표현하기 위한 노력의 결과물이라 보고 특히 제2차 세계대전 이후 유럽에 나타난 연출사조를 무대의상의 소재연출과 제작기술을 통해 이해해보는 것이다. 무대의상을 단순한 장식과 시각적 표현도구로 바라보지 않고 연출의 의도를 극적으로 전달 할 수 있는 표현 도구로 보는 관점은 제2차 세계대전을 기점으로 확연히 드러나므로 본 연구범위는 무대 의상의 위상이 단순한 장식뿐만 아니라 극적표현력까지도 포함하는 제2차 세계대전 이후부터 20세기 말까지 제한하였다. 연구방법은 먼저 무대의상 제작 시 사용되었던 소재의 간단한 사적 고찰을 살펴보고 제2차 세계대전 이후 나타난 유럽의 공연예술 사조를 대표할 수 있는 다섯 개의 무대연출 사조를 심미적, 창조적 기여도를 기준으로 다음과 같이 선별하였다. 1) Jacques Copeau의 단순화된 무대, 2) Bertolt Brecht의 정형화된 무대, 3) Grotowski의 본질적인 무대, 4) Robert Wilson의 측정된 무대 the Master, 5) Philippe $Decoufl\'{e}$의 포스트 드라마틱 무대. 각 사조별 사회문화적 맥락과 활용 가능한 소재의 발전과 무대의상에 미친 영향 그리고 그에 따른 무대의상의 소재연출과 제작기법의 다양화 등을 분석해 보았다. 무대의상은 연출의 의도에 따라 무대미술에서 차지하는 그 중요성이 때론 부각되기도 때론 감소하기도 했음을 알 수 있었는데 그 연구결과는 다음과 같다. 1) Copeau의 단순화된 무대를 위한 의상:배우의 제스처를 강조하기 위해 의상의 단순성 부자 2) Brecht의 정형화된 무대를 위한 의상: 의상의 인위적 정형성은 배우의 연기와 거의 동등한 중요성으로 인식 3) Grotowski의 본질적 무대: 무대 위 배우의 존재감을 강조하기 위해 의상이 거의 사라짐 4) Robert wilson의 측정된 무대: 무대 미술 구성 요소들(조명, 음향, 소품, 배우, 극본) 중 의상은 구체적 구성 요소 중 하나로서 배우의 몸과 동등하게 격상됨 5) $Decoufl\'{e}$의 포스트 드라마틱 무대: 멀티 테크놀로지 시대에 접어들면서 의상의 다기능성으로 배우의 몸을 대체할 수 있게 됨. 본 연구의 결과 무대의상의 위상이 연출의도를 추론 해 볼 수 있을 정도의 독립적 공연예술 작품으로 인정됨을 알 수 있었으며 무대의상의 위상이 변함에 따라 의상 제작가의 위상 또한 연출자의 의도대로 옷을 만드는 단순한 기술자가 아니라 고도의 지식과 경험을 요하는 만능 예술인으로서의 자질을 갖춰야하는 것으로 점점 바뀌어 가는 사실 또한 알 수 있었다.

• 보건의료산업학회지
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• 제2권1호
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• pp.137-154
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• 2008

The increase of the supply of medical service and the increase of hospitals have intensified the competition of hospitals, and the advancement towards internationalization in the opening of medical industry has triggered the infinite competition of medical profession. In addition, the high expectation of customers and quality improvement in the medical care in accordance with the improvement of overall income, and the change of active role of medical consumers according to the popularization and the improvement of rights awareness reflect the customer needs and choice in the medical service. Customers wanted to receive the kind and pleasant service under the up-to-date medical service. Therefore, as a solution, hospital coordinators were emerged for the purpose of smooth treatment and customer satisfaction by generalizing all service of hospital. Accordingly, this thesis attempted to investigate the effect of hospital coordinator education curriculum on the education satisfaction and the quality of medical service. In order to solve the purpose of this study, I, author reviewed the existing literatures, established hypothesis, and verified hypothesis by using the variety of statistics techniques such as reliability, validity, frequency analysis, and regression analysis. The verification of hypothesis is as followings: First, among education training factors of hospital coordinators, the quality of instructor significantly affects the satisfaction of hospital coordinator education training. Second, among training factors of hospital coordinator, the attitude of trainee significantly affects the training satisfaction of hospital coordinator. Third, among education training factors of hospital coordinator, education course significantly affects the training satisfaction of hospital coordinator education. As the qualities of instructor are better equipped, the satisfaction of education becomes higher. It indicates that the education method of instructors is important as an index to represent the qualities of instructor such as the appropriateness of education method, preparation, passion, visual materials, the adequacy of education procession, and specialized knowledge, and it has important effect on the satisfaction of education. In order to enhance the satisfaction of hospital coordinator education, the creation of education environment, making trainee concentrate on the education, is required by appropriately allocating programs, arousing interest in education, based on the attitude of trainee, discussion, and preliminary programs, preparation, ahead of enforcement of education. Fourth, the satisfaction of hospital coordinator education training significantly affects the reliability among the qualities of medical service. Fifth, satisfaction of hospital coordinator education training significantly affects hospitality I kindness among the qualities of medical service. If the education satisfaction of trainee is high, it is effective in the practical application such as dealing with complaints, the duty performance for the patients, and so on in offering the medical service, related to reliability and furthermore, we can find the positive change in the attitude change of medical professions related to the reliability of hospital coordinator. In addition, in the process of offering medical services such as the kind explanation on the duty, rapid response to the customers inquiry, and tidy uniform, practical effect was verified. Sixth, the education training factor of hospital coordinator significantly affects the reliability among the quality of medical service. Seventh, the education training factors of hospital coordinator significantly affect hospitality/kindness. In the education of hospital coordinator, the methods to attract the interest of trainee by emphasizing reliability should be sought and for gaining the practical effect of hospital coordinator education, the sufficient preparation and investigation on the education curriculum should be prerequisite and under this condition, intensified discussion on the instructor and education course is needed. In the design of education course, more education hours and subjects should be allocated in the part of hospitality in order to improve the practical application of hospitality. Therefore, it is meaningful in a sense that this study newly approached the components of hospital coordinator education and the need to modify the quality components of medical service in accordance with the study subjects was raised. This study also finds its meaning in that it provides basic materials for the study of future hospital coordinator education by suggesting the system development model of hospital coordinator education through preliminary study of education training. In addition, this study is meaningful in the aspect that it suggested the direction of education training by showing how the hospital coordinator education training would applied to the hospital coordinator course of the Continuing Education Center at Pusan and Kyungnam National University to some extent. Since all investigation of this study was approached from the side of hospital coordinator, the thoughts of patients who are beneficiaries of medical service, and care givers cannot be identified. Therefore, the satisfaction of patients and care givers through the experience of medical service, which is the essential prerequisite of medical service, should be importantly considered and investigated. Accordingly, The study of comparing and analyzing the views of both patients and care givers should be carried out in the future.