• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.79-84
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• 2009

Turbocharger has been widely used in many passenger cars in application with diesel engines because of high power and fuel efficiency. However, flow-induced noise (whoosh or hissing noise) which is generated within a compressor during its operation at marginal surge line can deteriorate noise characteristics. Hissing noise excitation is associated with the generation of turbulence within the turbocharger compressor and radiated through the transmission path in a turbocharger system. In this study, a expansion muffler with lids is devised and installed in the transmission path to reduce the hissing noise. Acoustic and fluid dynamic characteristics for the muffler are investigated which are related to the unsteadiness of turbulence and pressure in the turbocharger system. A transfer matrix method is used to analyze the transmission loss of the muffler. A simple expansion muffler with lids is proposed for the reduction of high frequency component noise. Turbulence simulation is carried out by a standard k - ${\varepsilon}$ model. An optimal design condition of the muffler is obtained by extensive acoustic and fluid dynamic analysis on the engine dynamometer with anechoic chamber. A significant reduction of the hissing noise is achieved at the optimal design of the muffler as compared with the conventional muffler.

• Journal of the Korean Professional Engineers Association
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• v.46 no.2
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• pp.36-43
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• 2013

풍력발전단지의 운영으로 인한 주된 소음은 풍력발전기의 고체음과 바람을 가르는 마찰 기류음으로 대별된다. 본 원고(原稿)에서는 소음레벨을($L_{PAN}$) 정량적으로 예측, 계산하는데 이용하는 소음예측식을 풍력발전에 맞게 이론적으로 해석하고, 소음발생원의 특성을 분석하여 운영시 소음영향 및 저감방안을 검토하였다. 풍력발전 사업계획시 소음예측식과 소음모델링(CadnaA version4.1, SoundPLAN version7.0 해석 결과 등)을 이용한 예측결과를 서로 비교 검토하고, 운영시(사후환경영향조사 등) 실제 소음레벨과 소음예측 결과를 서로 비교분석하여 데이터를 축척하길 바란다. 제언한 소음저감방안이 불충분한 경우 발전기의 배치와 설치간격, 발전기종 및 발전용량, 설치장소의 재선정 등을 추가 검토할 필요가 있다.

• Tuberculosis and Respiratory Diseases
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• v.63 no.6
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• pp.480-485
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• 2007

Background: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation that is not fully reversible. COPD has systemic effects, such as skeletal muscle dysfunction and abnormal weight loss. It also has been suggested that COPD is related to other chronic disease, such as cardiovascular disease, osteoporosis, and anemia. The aim of this study was to evaluate a symptom questionnaire and laboratory findings in subjects with air flow limitation. Methods: We evaluated a symptom questionnaire and laboratory findings in subjects with airflow limitation detected by spirometry in conjunction with the Second Korean National Health and Nutrition Examination Survey. A total of 9,243 adults over the age of 18 were recruited. Among the adults, we finally analyzed 2,217 subjects who met the acceptability and repeatability criteria of spirometry, showed normal findings on chest radiography, and were older than 40 years of age. Results: There were 288 subjects with airflow limitation as determined by spirometry. The frequency of respiratory symptoms such as cough, sputum and wheezing were significantly higher in subjects with airflow limitation (p <0.01). Hemoglobin and hematocrit levels were higher in subjects with airflow limitation (hemoglobin level 13.98 mg/dL vs. 13.62 mg/dL, hematocrit 42.10% vs. 40.89%; p<0.01). The HDL cholesterol level was lower in subjects with airflow limitation (44.95 mg/dL vs. 45.60 mg/dL; p<0.01). There was no significant difference in the total cholesterol, triglyceride, blood urea nitrogen, creatinine, and fasting glucose levels. Conclusion: In subjects with airflow limitation, prevalence of respiratory symptoms was higher than in normal spirometry subjects and the levels of hemoglobin and the hematocrit were higher. The HDL cholesterol level was lower in subjects with airflow limitation.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1979.05a
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• pp.8.3-8
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• 1979

Dohne (1944) has studied the consumption of air during phonation in patients with dysphonia and Arnold (1955, 1958) reported that the maximum phonation time is frequently reduced to a few seconds in paralytic dysphonia. Also, Nishikawa investigated the relation among the vital capacity, maxium phonation time, caculated mean flow rate and various vocal characteristics in patients with hoarseness. Authors have studied the aerodynamic characteristics of the vocal tract in the following aspects, using 9 L. Respirometer made in Collins Inc.; 1. Maximum phonation time 2. Maximum phonation volume 3. Mean flow rate 4. Vocal velocity index

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.233-239
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• 2006

The effect of the joint condition of automotive muffler shell and baffle on radiated noise from muffler shell Is studied. Shell vibration characteristics, especially shift In natural frequency and change in of response amplitude, was identified from finite element analysis and modal tests for various joint conditions between shell and baffle. When there is heat expansion and inner pressure from the exhaust 9as in the muffler with elliptical cross section, the shell expands out, and construct gap with baffles. This gap causes more degrees of freedom of shell vibration and natural frequency shift. By welding the muffler shell to the baffles or using a dual shell muffler, the radiated noise problem could be mitigated supplying more a rigid joint and damping, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.78-83
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• 2003

General algorithm is developed for the prediction of internal flow-induced noise. This algorithm is based on the integral formula derived by using the General Green Function, Lighthills acoustic analogy and Curls extension of Lighthills. Novel approach of this algorithm is that the integral formula is so arranged as to predict frequency-domain acoustic signal at any location in a duct by using unsteady flow data in space and time, which can be provided by the Computational Fluid Dynamics Techniques. This semi-analytic model is applied to the prediction of internal aerodynamic noise from a throttle valve in an automotive engine. The predicted noise levels from the throttle valve are compared with actual measurements. This illustrative computation shows that the current method permits generalized predictions of flow noise generated by bluff bodies and turbulence in flow ducts.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2913-2917
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• 2007

Turbocharger has been widely used in many passenger cars in application with diesel engines because of high power and fuel efficiency. However, flow-induced noise (whoosh or hissing noise) which is generated within the compressor during its operation at marginal surge line can deteriorate noise characteristics. Hissing noise excitation was associated with the generation of turbulence within the turbocharger compressor and radiated through the transmission path in turbocharger system. In this study, a sharp-edged reactive-type muffler was devised and installed in the transmission path to reduce the hissing noise. Acoustic and fluid dynamic characteristics for the muffler were investigated which is related to the unsteadiness of turbulence and pressure in turbocharger system. A transfer matrix method was used to analyze the transmission loss of the muffler. Simple expansion muffler with extended tube of the reactive type is proposed for the reduction of high frequency component noise. Turbulence computation was carried out by a standard ${\kappa}-{\varepsilon}$ model. An optimal design condition of the muffler was obtained by extensive acoustic and fluid dynamic analysis on the engine dynamometer with anechoic chamber. A significant reduction of the hissing noise was achieved at the optimal design of the muffler as compared with the conventional turbocharger system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.734-741
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• 2010

In this paper, an intake RCV system for low noise turbo engine was developed through optimization process of a geometric path of compressor housing and an open rate of recirculation valve. At first, the critical customer requirement from voice of customer was defined and quality function deployment of an intake RCV system was executed. And then, the renovative concept design using pugh matrix method was selected as final concept for satisfaction of requirement. Simultaneously, system analysis was carried by function diagram and fishbone diagram. Next, control factors and levels for the optimal design were performed. And, the optimal design of an intake RCV system was studied using design of experiment. Conclusively, we achieved not only cancellation tip-out noise at the driving condition but also improvement of NVH commodity through optimization process of an intake RCV system, which is optimal configuration of compressor housing and recirculation valve.

• Journal of Korean Medical classics
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• v.19 no.2 s.33
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• pp.46-52
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• 2006

${\ulcorner}$황제내경(黃帝內經)${\lrcorner}$ 내함한의학이론(內含韓醫學理論) 기중삼응삼양적내용비상난(其中三陰三陽的內容非常難) 기원인사(其原因是)${\ulcorner}$황제내경(黃帝內經)${\lrcorner}$ 중삼음삼양적내용비상복집(中三陰三陽的內容非常複雜), 특별시삼음삼양적시간배속매편화일양(特別是三陰三陽的時間配屬每篇不日樣) 본론문통과관우(本論文通過關于子) ${\ulcorner}$황제내경(黃帝內經)${\lrcorner}$ 중삼음삼양적시간배속진행연구(中三陰三陽的時間配屬進行硏究), 득출여하결론(得出如下結論), 운기지주기순서춰시오행(목화토금수)순서(運氣之主氣順序就是五行(木火土金水)順序), 저설명주기변화주요근거형지변화(這說明主氣變化主要根據形之變化), 운기지객기순서취시기지대(運氣之客氣順序就是氣之大小)(일양(一陽)${\longrightarrow}$이양(二陽)${\longrightarrow}$삼양(三陽)${\longrightarrow}$일음(一陰)${\longrightarrow}$이음(二陰)${\longrightarrow}$삼음(三陰))${\longrightarrow}$, 저설명객기변화주요근거기지변화(這說明客氣變化主要根據氣之變化) ${\ulcorner}$소문맥해(素問脈解)${\lrcorner}$ 적삼음삼양월별배속시음관(11월:태음)(的三陰三陽月別配屬是陰關(11月:太陰)${\longrightarrow}$양관(1월:태양)(陽關(1月:太陽)${\longrightarrow}$음합(3월:궐음)(陰闔(3月:厥廠)${\longrightarrow}$양합(5월:양명)(陽闔(5월:陽明))${\longrightarrow}$음추(7월:소음)(陰樞(7月:少陰)${\longrightarrow}$양추(9월:소양)(陽樞(9月少陽). 태양소음시음양세력적기초(太陽少陰是陰陽勢力的基礎), 소이상위표리(所以相爲表裏). 소양소음시음양세력적중간(少陽少陰是陰陽勢力的中間), 소이사위표리(所以杞爲表裏) 태음궐음시음양세력적전성기(太陰歐陰是陰陽勢力的全盛期), 소이상위표리(所以相爲表裏) 차료리적의사반영경락류주(此表養的意思反映經絡流注). 태음양명경류주신체전면(太陰陽明經流注身體前面), 태양소음경류주신체후면( 太陽少陰經流注身體後面 ), 소양궐음경류주신체측면(少陽厥陰經流注身體側面). ${\ulcorner}$령추경맥(靈樞經脈)${\lrcorner}$적12경맥류주순서시태음양면경(的12經脈流注順序是太陰陽明經)${\longrightarrow}$소음태양경(少陰太陽經)${\longrightarrow}$궐음소양경적표리경락위주(厥陰少陽經的表裏經絡爲主). 수선매기류주태음양명경적이유(首先脈氣流主太陰陽明經的理由), 취시후천수곡정미화호흡대기결합이형성경맥지기(就是後天水穀精微和呼吸大氣結合而形成經服之氣). 지후맥기류주소음태양경(之後脈氣流注少陰太陽經), 설명순행태음양명경적후천영양물질전입한열경락이위신(說明盾行太陰陽陽明經的後天營養物質轉入寒熱經絡而爲寫薪), 기차맥기순해궐음소양경적(其次脈氣盾行厥陰少陽經的), 인위한열경락지화기피궐음소양경지풍기조절이후조절조습경락(因爲寒熱經絡之火氣被厥陰少陽經之風氣調節而後調節操濕經絡), 비여작반시(比如作飯時), 화기취시소음태양경(火氣就是少陰太陽經), 풍기취시궐음소양경(風氣就是厥陰少陽經), 정내지반취시태음양명경.(鼎內之飯就是太陰陽明經). ${\ulcorner}$령추음양계일월(靈樞陰陽緊日月)${\lrcorner}$ 적삼음삼양월별배속주요시추관합합관추순서(的三陰三陽月別配屬主要是樞關闔闔關樞順序). 저양배서적원인시개문화관문과정(這樣排序的原因是開門和關門過程). 재춘하(在春夏), 양경락지맥기여개문관문과정(陽經絡之脈氣如開門關門過程), 수착추관합합관추순서순행(隨看樞關闔闔關樞順序盾行), 재추동(在秋冬), 음경락지맥기여개문폐문과정(陰經絡之脈氣如開門閉門過程), 수착추관합합관추순행(隨看樞關闔闔關樞盾行).

• The korean journal of orthodontics
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• v.27 no.1
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• pp.91-103
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• 1997

This paper aimed to study what the influences of orthodontic treatment of pronunciation are. We compared the duration and the acoustic wave patterns of Korean consonants pronounced by a control group with those of a patient who had his four premolars extracted and had been given orthodontic treatment The results were as follows : 1. Compared to the control group, the treatment group had a longer duration time of consonant pronunciation for all consonants but "ㅅ(s)" and "ㅌ($(t^h)$" in CV(consonant-vowel) pairs. Especially in the case of "ㅈ(dz)", "ㅆ$({\varphi}^h)$" for CV-pairs, and "ㄷ(d)" in VCV(vowel-consonant-vowel) clusters, the duration of consonant sound showed a sharp contrast between the control group and the treatment group. 2. There were clear differences in the acoustic wave patterns of "ㅉ(ts)", "ㅆ$({\varphi}^h)$" and "ㅊ$(c^h)$", all of which were in VCV-clusters. The acoustic wave pattern of "ㅉ(ts)", when pronounced by the treatment group, was stronger than the control group's. This phenomenon was most remarkable in the transitive section where the "ㅉ(ts)" sound flowed into the following vowel. When a preceding vowel shifted to the consonant "ㅆ$({\varphi}^h)$", the attack property of the appeared clearly in the acoustic waves of the treament group, while in the control group the starting point of consonart was indistinctive. Consonant duration for the treatment group was longer, and the appearance of a zero crossing point in the acoustic wave was more frequent. In the case of "ㅊ$(c^h)$", the treatment group produced a strong acoustic wave, and the property of aspiration was obvious in it. 3. When the treatment group pronounced "ㄷ(d)" and "ㅈ(dz)" in CV-pairs, the acoustic-wave was similar to that of aspirated "ㅌ$(t^h)$" and "ㅊ$(c^h)$". 4. The aspirated "ㅌ$(t^h)$" and "ㅊ$(c^h)$" pronounced by the treatment group showed the stronger airstream and acoustic wave form.